I THE CHEMISTRY OF THE TERPENES HEUSLER - POND. THE CHEMISTRY OF THE TEKPENES BY F. HEUSLER, Ph.D., Privatdocent of Chemistry in the University at Bonn. AUTHORIZED TRANSLATION BY FRANCIS J. POND, M.A., Ph.D., Assistant Professor in The Pennsylvania State College. Carefully Revised, Enlarged and Corrected. PHILADELPHIA : P. BLAKISTON'S SON & CO. 1012 WALNUT STREET. 1902 TO Geheimeath Peofessor OTTO WALLACH THIS VOLUME IS GRATEFULLY DEDICATED BY THE AUTHOR AND TRANSLATOR. 1735? PREFACE TO THE AMERICAN EDITION. The favorable reception of the German edition of Dr. Heusler's work renders it unnecessary to offer an excuse for presenting this translation and revision of " The Terpenes." The chemistry of the terpenes covers a portion of organic chemistry which has ex- perienced a very remarkable development in the past few years, and, since the chapter on the terpenes in most works on organic chemistry is necessarily very limited, it seemed desirable to have at least one book in English which should be devoted exclusively to this subject. It is desired that this translation shall serve this purpose. That the German edition has already proved of great value to chemists especially active in this field is evidenced by the remark of Doctors Gildemeister and Hoffmann in their book, "The Volatile Oils": "The monograph by Heusler on the terpenes has proved itself well-nigh indispensable for the scientific investi- gations of terpenes and their derivatives." Before presenting this translation, it has been necessary to care- fully review the very numerous contributions on the terpenes which have been published since the German edition was issued, and to introduce the results of these investigations in this edition ; in doing this, it will be obvious that, although a vast amount of literature has been condensed into as small a space as possible and many important compounds are merely mentioned with references to original papers, the book has been enlarged to a degree very unusual in a translation. The task has proved a severe one, but I have endeavored to keep the plan of Dr. Heusler's work intact, and have introduced the large amount of new material in those places which appeared to me the most desirable. I have not distinguished in any way the separation of the old and new material, as such a plan did not seem advisable. vii Vlll PEEP ACE. In the translation I have studied to keep as close to the original as possible, and yet give a clear version. The chapter of intro- duction is without change from the original edition. The table of constituents of the ethereal oils, which was added to the German work, has been omitted because such a list is no longer of so great importance since the translation of "The Volatile Oils" by Professor Kremers. Following Dr. Heusler's plan, the many researches on the derivatives of Japan camphor, such as the in- vestigations on camphoric acid, etc., have not been introduced. An index has also been added. The writer desires to express his obligation to Mr. Jesse B. Churchill, Instructor of Chemistry at The Pennsylvania State College, for valuable assistance in the reviewing of literature, preparation of index and proof-reading. F. J. Pond. State College, Pa., May, 1902. PREFACE TO THE GERMAN EDITION. The following monograph was originally compiled for the " Handwörterbuch der Chemie." The article which was written for this collective work on chemistry was printed some months after the completion of the manuscript ; at this time a review of the work which had appeared during these months was added, the effort being made to render this review as complete as possible. The fact that at the present time the chemistry of the terpenes occupies a very prominent position in scientific interest led the author and publishers to publish the article separately in book form. The outward form of the " Handwörterbuch " was of course retained in the publication of this book. Most of the literature of the intervening months has been reviewed, and certain inaccu- racies which appeared in the original article have been corrected. The publication of this book may be justified by the fact that the recent advances of the chemistry of the terpenes are, perhaps, not generally recognized. I may refer to the chapter of introduction for the principal points of view from which the compilation of the monograph has proceeded ; I still regard these principles as correct. I wish to express my thanks for the valued assistance which Mr. E. Gildemeister of Leipzig and Mr. J. Bredt of Bonn have repeatedly extended to me in the course of my work. I am indebted to my friend, Dr. Gildemeister, not only for the table of constituents of the ethereal oils, but he has repeatedly placed his experience at my disposal in reviewing certain parts of the work, and finally in reviewing the entire book. My honored colleague, Dr. J. Bredt, has frequently given me valuable suggestions, and has kindly read one proof. F. Hetjsler. ix TABLE OF CONTENTS. Page. Introduction 17 SPECIAL PART. Hemiterpenes, CsHg 31 Isoprene, C5H8 31 Terpenes Proper, CioHi 6 34 1. Pinene 34 2. Camphene 56 3. Fenchene 66 4a. Limonene 71 4b. Dipentene 85 5. Sylvestrene 99 6. Carvestrene 103 7. Terpinolene 105 8. Phellandrene 108 9. Terpinene 112 10. Thujene (Tanacetene) 118 11. Terpene from the Resin of Indian Hemp 119 12. Synthetical Terpene 120 13. Fenchelene 120 14. Euterpene 120 15. Tricyclene 121 16. Bornylene 121 17. Sabinene 121 Hydrocarbons, CioHis 123 1. Dihydrocamphene 123 2. Isodihydrocamphene 124 3. Carvomenthene 124 4. Menthene 126 Hydrocarbons, C10H20 130 Oxidized Compounds Related to the Terpenes, C10H16 133 I. Substances which can not be Regarded as Deriva- tives OF THE HyDROCYMENES. (ANALOGUES OF Pinene, Camphene, Fenchene ) 133 xi xii TABLE OF CONTENTS. Page. 1. Camphor, Ci 0 Hi 6 0 133 2. Borneol, C10H17OH 141 3. Isoborneol, C10H17OH 146 4. Camphene Glycol, Ci 0 Hi 6 (OH) 2 151 5. Camphol Alcohol, C10H19OH 152 6. Camphenone, C10H140 152 7. Pinocamphone, CioHi 6 0 154 8. Pinocarapheol, C10H17OH 155 9. Fenchone, CioHi 6 0 155 10. Fenchyl Alcohol, C10H17OH 170 11. Isofenchyl Alcohol, C10H17OH 174 12. Fencholenyl Alcohol and Isofencholenyl Alcohol, C 10 H 17 OH 176 13. Fenchenole, CioHigO 177 II. Compounds Which May be Regarded as Derivatives op the Hydrocymenes 178 A. Substances Containing two Ethylene Linkages. Ketones, C10H14O, and Alcohols, CioH 15 OH 178 1. Carvone, C10H140 178 2. Carveol Methyl Ether, C10H15OCH3 197 3. Eucarvone, C10H14O 198 4. Pinocarvone, C10H140 201 5. Pinocarveol, C10H15OH 202 6. Pinenol, C10H15OH 202 7. Pinenone, C10H140 203 8. Limonenol, C10H15OH 203 9. Limonenone, C10H140 204 10. Sabinol, C10H15OH 204 B. Substances Containing one Ethylene Linkage. Ketones, CioHi 6 0, Alcohols, C10H17OH, and Oxides, Ci 0 H 16 O... 206 1. Dihydrocarvone, CioHi 6 0 206 2. Dihydrocarveol, C10H17OH 212 3. Carvenone, CioHi 6 0 216 4. Carone, Ci 0 Hi 6 O 219 5. Dihydroeucarvone, CioHi 6 0 223 6. Dihydroeu carveol, C10H17OH 224 7. Thujone (Tanacetone), Ci 0 Hi 6 0 224 8. Thujyl Alcohol (Tanacetyl Alcohol), Ci 0 H 17 OH 234 9. Isothujone, Ci 0 Hi 6 0 235 10. Carvotanacetone, C10H160 236 11. Pulegone, Ci 0 Hi 6 0 237 12. Isopulegol, C10H17OH, and Isopulegone, Ci 0 Hi 6 0 247 TABLE OF CONTENTS. XÜi Page. 13. Menthenone, Ci 0 Hi 6 0 250 14. Isocarnphor, CioHißO 251 15. Pinolone, Ci 0 Hi 6 O, and Pinolol, C10H17OH 253 16. A6-Menthene-2-one, Ci 0 Hi 6 0 253 17. Terpineol, Ci 0 Hi 7 OH 254 18. Isomeric Terpineol (A4< 8 >-Terpen-l-ol), melting at 69° to 70°, C10H17OH 269 19. Isomeric Terpineol, C10H17OH, melting at 32° to 33°. 273 20. Pinole, C 10 Hi 6 0 274 21. Eudesmole, Ci 0 Hi 6 0 285 C. Substances Without an Ethylene Linkage. Ketones, CioHi 8 0, Alcohols, C10H19OH and CioHi 8 (OH)2, Oxides, CioHigO, etc 287 1. Tetrahydrocarvone (Carvomenthone), CioHi 8 0 287 2. Tetrahydrocarveol (Carvomenthol), C10H19OH 291 3. Tetrahydroeucarvone, CioHigO 293 4. Thujamenthone, CioHigO 294 5. Thujamenthol, C10H19OH 295 6. Menthone, Ci 0 Hi 8 0 295 7. Menthol, C10H19OH 308 8. Tertiary Carvomenthol, C10H19OH 316 9. Tertiary Menthol, C10H19OH 317 10. Terpine, Ci 0 Hi 8 (OH) 2 318 11. Menthene Glycol, Ci 0 Hi 8 (OH) 2 323 12. Cineole, Ci 0 Hi 8 0 323 13. Terpan-1, 4, 8-triol, Ci 0 Hi 7 (OH) 3 334 14. Trioxyhexahydrocymene, CioHi7(OH)3 334 15. Pinole Hydrate, Ci 0 Hi 7 O-(OH) 334 16. Limonetrol, CioHi 6 (OH) 4 334 17. Pinole Glycols, Ci 0 Hi 6 O(OH) 2 334 Amido-Deeivatives of the Teepenes 336 I. Bases which can not be Eegaeded as Deeivatives of the üydbocymenes. (analogues of plnene, Camphene, Fenchene, and of Campholenic acid and Fencholenic Acid) 336 1. Pinylamine, C10H15NH2 336 2. Amidoterebentene, C10H15NH2 338 3. Bornylamines, C10H17NH2 340 4. Camphylamines, C9H15CH2NH2 346 5. Fenchylamine, C10H17NH2 347 6. Fencholenamine, C9H15CH2NH2 351 7. Campholamine, C9H17CH2NH2 353 xiv TABLE OF CONTENTS. Page. II. Bases which may be Regarded as Derivatives of the Hydrocymenes 354 A. Amines, C10H15NH2, Containing two Ethylene Linkages 354 1. Carvylamines, C10H15NH2 354 B. Amines, C10H17NH2, Containing one Ethylene Linkage 356 1. Dihydrocarvylamine, C10H17NH2 356 2. Carylamine, C10H17NH2 358 3. Vestrylamine, Ci 0 H 17 NH 2 359 4. Dihydroeucarvylamine, C10H17NH2 359 5. Thujylamine (Tanacetylamine), C10H17NH2 360 6. Isothujylamine, C10H17NH2 362 7. Pulegylamine, C10H17NH2 362 C. Amines, C10H19NH2, Without an Ethylene Linkage 364 1. Carvomenthylamine (Tetrahydrocarvylamine), C10H19- NH 2 364 2. Menthylamine, CioHi 9 NH 2 365 3. Tertiary Carvomenthylamine, C10H19NH2 373 4. Tertiary Menthylamine, C10H19NH2 374 Amido-Derivattves op Phellandrene 374 1. Amidophellandrene, C10H15NH2 374 2. Diamidophellandrene, CioHi6(NH2)2 375 Olefinic Members of the Terpene Series 377 A. Hydrocarbons 377 1. Myrcene, Ci 0 Hi 6 377 2. Anhydrogeraniol, C10H16 379 3. Olefinic Terpenes in Oil of Hop and Oil of Origanum. 380 4. Linalolene, CioHis 380 5. Hydrocarbon, ^CioHis, obtained from Menthonylamine, 380 B. Oxygenated Compounds 381 (a) Alcohols 381 1. Linalool, C10H17OH 381 2. Geraniol, C10H17OH 387 3. Menthocitronellol, C10H19OH 393 4. Citronellol, C10H19OH 394 (b) Aldehydes 396 1. Geranial (Citral), Ci 0 Hi 6 0 396 2. Menthocitronellal, Ci 0 Hi 8 0 409 3. Citronellal, Ci 0 Hi 8 0 409 C. Amines 413 1. Menthonylamine, C10H19NH2 413 Sesquiterpenes and Polyterpenes 414 Sesquiterpenes, C15H24, and Sesquiterpene Alcohols, C15H25OH... 414 TABLE OF CONTENTS. XV Page. 1. Cadinene, C15H24 414 2. Caryophyllene, C15H24 417 3. Clovene, C 15 H24 421 4. Humulene, C15H24 421 5. Cedrene, C15H24, and Cedrol ("Cedar Camphor"), C15H25OH 423 6. Cubeb Camphor, C15H25OH 424 7. Ledum Camphor, C15H25OH, and Ledene, C15H24 425 8. Patchouly Alcohol, C15H25OH, and Patchoulene, C15H24 425 9. Guaiol, C15H25OH 426 10. Santalol, C15H25OH, and Santalene, C15H24 426 11. Galipol, C15H25OH, and Galipene, C15H24 428 12. Caparrapiol, C15H25OH, and Caparrapene, C15H24 428 13. Zingiberene, C15H24 429 14. Olefinic sesquiterpene, C15H24, from the oil of citro- nella 430 Diterpenes, C20H32 431 Triterpene8, C30H48 432 1. a. and /?-Amyrin, C30H49OH 432 Tetraterpenes, C40H54 435 THE TEEPENES. Those hydrocarbons which have the empirical constitution, C 5 H 8 , are termed terpenes. Four main classes are recognized : Hemiterpenes, C 5 H 8 , Terpenes proper, C 10 H 16 , Sesquiterpenes, C 15 H 24 , Polyterpenes, (C 5 H g ) x . The terpenes proper and the sesquiterpenes form the most im- portant constituents of the ethereal oils. In the latter, several terpenes often occur together, and further, the ethereal oils fre- quently contain oxidized compounds which in many cases are not separable from the terpenes by fractional distillation, or only im- perfectly so. The result of these conditions was, that during the period be- fore it was known how to sharply characterize the separate ter- penes by chemical reactions, and to determine them as individuals, mixtures of this character were often regarded as chemical in- dividuals, and were accordingly given independent names. To Professor O. Wallach belongs the distinction of having elevated the methods of the terpene chemistry, by a series of superior experimental investigations, to such a plane, that the recognition and separation of the several terpene hydrocarbons have become relatively simple matters for the chemist. These methods gave the first possibility of an actual working system to these substances, and moreover permitted the accurate establishment for the first time of the numerous transformations, which, under the influence of the greatest variety of reagents, take place so easily in this group of hydrocarbons. It has already been mentioned that many oxidation products are present with the terpenes in the ethereal oils. It is evident that these compounds, occurring together in the plants, are very closely related to each other. What these relations are is ren- dered entirely clear by the study of the terpenes. Not only have many terpenes been artificially prepared from such natural oxi- dized compounds, but also a complete series of oxidation products have been successfully secured from natural terpenes, and these 2 17 18 THE TERPENES. substances are isomeric with, or closely related to, the natural oxygen-containing members of the terpene group. The so-called camphors, a name long used to designate these oxidized compounds, have been brought into so close a relation to the terpenes that a separate consideration of these two classes of compounds is no longer justifiable. In fact, it is impossible to develop the chemistry of the terpenes unless these oxygen-con- taining compounds are considered as members of the terpene series. With this point in view the following monograph has been com- piled, and only the one reason of outward conformity has pre- vented the carrying out of this fundamental idea to the end. Japan camphor, while very closely allied to the terpenes, has, however, such an extremely large number of derivatives that an exhaustive description of them would demand as large a space as the derivatives of all the remaining members of the terpene group taken together. Hence the only derivatives of this compound to be mentioned will be those which stand in an especially close re- lation to other members of the terpene group. While the discussion of camphor and its derivatives will be limited, an equally exhaustive treatment for the remaining oxy- gen- and nitrogen-containing compounds of the terpene group will be sought, as for the terpenes themselves. The terpenes proper may be divided into two groups. The hydrocarbons of the first group contain one ; those of the other group contain two ethylene linkages. As a class, the terpenes of the latter group may apparently be regarded as true dihydrocy- menes. The known tetrahydrocymenes and hexahydrocymene, which are closely related to these terpenes, are discussed in the following treatise. Corresponding to hexahydrocymene, which does not occur nat- urally, are oxygen-containing compounds which are widely dis- tributed in nature, namely, menthone, C 10 H ]8 O, and the alcohol corresponding to this ketone, menthol, C, 0 H 19 OH. Two com- pounds, carvomenthone, C 10 H lg O, and carvomenthol (tetrahydro- carveol), C 10 H 19 OH, structural isomerides of the above-mentioned substances, are to be considered as the completely hydrated parent- substances of an extremely large number of unsaturated, oxyge- nated members of the terpene group. Nevertheless, they do not themselves occur in nature. If one molecule of water be eliminated from menthol or carvo- menthol, hydrocarbons, C 10 H 18 , are formed, which can be consid- ered as structural isomerides of tetrahydrocymene. The following formulas illustrate the constitution of these compounds. (For the nomenclature, see page 23.) INTRODUCTION. 19 CH 3 H HjC CH 3 Hexahydrocymene (Terpane, Menthane). H 3 C CH 3 Menthone ( /?-Ketohexahydrocymene, Terpan-3-one, Menthan-3-one). HOH H S C CH 3 Menthol ( /3-Oxyhexahydrocymene, Terpan-3-ol, Menthan-3-ol). H 3 C CH 3 Menthene ( A 3 -Tetrahydrocymene, A*-Terpene, A 3 -Menthene). H 3 C CH S Carvomenthone (a-Ketohexahydrocymene, Terpan-2-one, Menthan-2-one). H S C CHj Carvomenthol ( a-Oxyhexahydrocymene, Terpan-2-ol, Menthan-2-ol). A, H 2 C CH hJAh, (pi H 3 C CH 3 Carvomenthene ( A'-Tetrahydrocymene, A'-Terpene, A '-Menthene). Other compounds, isomeric with menthol and carvomenthol, are known, which possess the character of tertiary alcohols, and, ac- cording to Baeyer, have the following constitution : 20 THE TERPENES. CH H 3 C CH, H,C v ÖH, x>h CH A H 3 C CH, Tertiary Menthol. Tertiary Carvomenthol. Theory also clearly allows other isomeric tetrahydrocymenes to be predicted, although they are still unknown. By consideration of the above-mentioned derivatives of hexa- hydrocymene, it had to be accepted as a fact, according to the views prevailing at that time, that a third ketohexahydrocymene, isomeric with menthone and carvomenthone, could not exist. The fact more recently established by Wallach that such an isomeric ketone, thujamenthone, and its corresponding alcohol do exist, deserves therefore to be emphasized at this point as a matter of especially great theoretical importance. If we suppose one methylene group in the hydrocarbons, C 10 H 18 , to be replaced by a carbonyl group, we arrive at the ketones, C 10 H 16 O, which contain one double linkage, and are to be regarded as 10 derivatives of tetrahydrocymene. By reduction of these ke- tones, C 10 H 16 O, secondary alcohols, C 10 H 17 OH, are formed which may be transformed into terpenes, C 10 H 16 , by the elimination of one molecule of water. The reverse process, by which the alco- hols may to some extent be prepared from the terpenes, C 10 H 16 , by the addition of the elements of water, is also possible. Ketones, C 10 H 16 O, of this character, which may be considered as ketotetrahydrocymenes, and their corresponding secondary alcohols (oxy tetrahydrocymenes), have recently been discovered in exceedingly large numbers. The constitution of these compounds has not yet been determined with such a degree of accuracy that an extended discussion of the various views held in regard to the constitution of the separate members of this class would be of value here. Nevertheless, we recognize certain of these sub- stances which must be regarded as derivatives of menthone, and certain others which are to be considered as derivatives of carvo- menthone. The following compounds are derived from men- thone : pulegone, and also in all probability the ketone, menthe- none, which is formed by heating nitrosomenthene with hydro- chloric acid. INTRODUCTION. 21 From carvomenthone are derived : dihydrocarvone and di- hydrocarveol ; carvenone • dihydroeucarvone and dihydroeu- carveol ; thujone (tanacetone) and thujyl alcohol ; and carvotan- acetone. According to Wallach, isothujone appears to correspond to neither menthone nor carvomenthone. By reduction it yields the above-mentioned thujamenthone. Aside from the secondary alcohols, C 10 H 17 OH, just referred to, tertiary alcohols, C 10 H 17 OH, are known, which are also to be con- sidered as oxytetrahydrocymenes. The constitution of one of these tertiary alcohols, terpineol (melting point 35°), was de- termined by Wallach and Baeyer independently of each other, but with perfect agreement in result, and until quite recently terpineol was represented by their formula : H 3 C CH 3 Later experiments by Wallach, on the one hand, and Tiemann, Semmler, and Schmidt on the other, however, entitle the formula H 3 C CH 3 to an equal consideration, and, indeed, it appears in all probability to be the correct representation of the constitution of terpineol. A large number of bases, C 10 H, 7 NH 2 , which have been prepared by various methods from the ketones, C 10 H 16 O, or the alcohols, C 10 H 17 OH, are to be considered with the latter. If a molecule of water is withdrawn from the alcohols, C 10 H 17 OH, or ammonia from the bases, C 10 H 17 NH 2 , a class of terpenes, C 10 H , 22 THE TERPENES. is derived, which contain two ethylene linkages, and are to be regarded as dihydrocymenes. To this group of terpenes belong : Limonene (Dipentene), Carvestrene, Sylvestrene, Terpinolene. In regard to another terpene, thujene, which belongs here, only a few statements have hitherto been submitted. Regarding the constitution of these hydrocarbons, it is worthy of note that Baeyer believes the constitution of terpinolene, which results by the elimination of water from the above-mentioned terpineol (melting point 35°), to be proved with a degree of ac- curacy equal to that of any other organic compound. h,c CH 2 A H 3 C CH S Terpinolene. It will be judicious, however, to use this formula cautiously for the present, since Baeyer's proofs rest to some extent on con- clusions drawn from analogy, and their strength must at all events be supported by the presentation of an extended series of observa- tions. Various views have been held from time to time with respect to the position of the double linkage in the other terpenes of the limonene group ; but it would be of little interest at this time to discuss the proposed formulas, since the investigations regarding these have not yet reached definite conclusions. If it be imagined that one of the methylene groups in the ter- penes of the limonene series is oxidized to a carbonyl group, ketones, C 10 H 14 O, are derived, which contain two ethylene linkages, and are to be considered as ketodihydrocymenes. Again theory allows two classes of these ketones to be predicted, of which one corresponds to menthone, the other to carvomenthone. Both classes may be transformed into these two saturated ketones by hydration. With the ketones, C 10 H 14 O, which are derived from menthone, we are as yet unacquainted. The known ketones, C 10 H 14 O, INTRODUCTION. 23 Qarvone, Eucarvone, Pinocarvone, are all derivatives of carvomenthone, and this substance owes its name to precisely this relation which it bears to carvone. An alcohol, C 10 H 15 OH, corresponding to carvone, is known only in its methyl ether, but, on the other hand, an alcohol, C 10 H 15 OH, pinocarveol, exists corresponding to pino- carvone. These theoretical considerations render it apparent that all the hydro-derivatives of cymene can be transformed into each other by the greatest variety of methods. The nomenclature of the above-mentioned group of hydro- cymene derivatives is rendered difficult, if it be desired to rationally express the structure of a compound in its relation to hexahydrocymene as the parent-substance. Baeyer 1 has there- fore advanced the proposition to designate hexahydrocymene as terpane; the tetrahydrocymenes, according to the Geneva com- mission, as terpenes ; and the hydrocarbons, C 10 H 16 , hitherto known as terpenes, as terpadienes. The position of the double linkage is indicated by the same method as that introduced by Baeyer in the case of the hydro- phthalic acids ; thus, as an example, the above-mentioned struc- tural formula of terpinolene would be designated as follows : According to Baeyer, the ketones, C 10 H 18 O, are termed ter- ■panones, the alcohols, C 10 H 19 OH, terpanols, with an index figure to designate the carbon atom to which the oxygen is attached. The ketones, C 10 H 16 O, and the alcohols, C 10 H 17 OH, Baeyer designates as terpenones and terpenoid. 7 CH 3 H„C5 3CH. 2 W 4 H 3 C9 10CH3 A-l, 4(8)-Terpadiene. 'Baeyer, Ber., 27, 436. 24 THE TERPENES. This system of nomenclature, introduced by Baeyer, has the one disadvantage of giving the old familiar name terpene to the hydrocarbons, C 10 H 18 . In order to avoid this difficulty, but, at the same time, to preserve the unquestionable advantage of Baeyer's system of nomenclature, Wagner 1 has suggested that hexahydro- cymene be called menthane. The hydrocarbons, C 10 H 18 , retain the name menthene, which has already been employed for one member of this group, while the dihydrocymenes, C 10 H 16 , may be called rnenthadienes, or terpenes as hitherto. In the meantime no agreement has been reached as to whether Baeyer's or Wagner's nomenclature shall be introduced. For the sake of completeness it might be noticed at this point, that in accordance with a proposition by Wallach, 2 men- thone is often designated as ß-, carvomenthone as a-keto- hexahydrocymene, and, correspondingly, all unsaturated ke- tones which yield menthone by hydration are termed ß-, but all ketones which form carvomenthone by hydration, a-keto- derivatives. It has already been mentioned that in addition to the terpenes of the limonene series, other terpenes are known which contain only one ethylene linkage, and can not be regarded as simple hydra- tion products of cymene. Especially is this the case in a family of closely related terpenes consisting of : Pinene, Camphene, Fenchene. To these terpenes correspond also saturated hydrocarbons, C 10 H 18 . If it be imagined, in a manner similar to that above, that one methylene group in these hydrocarbons, C 10 H 18 , be replaced by a carbonyl group, the ketones, C 10 H 16 O, are derived, which are saturated compounds. These ketones, camphor and fenchone, sustain the same relation to the three terpenes of this class, as the above-mentioned ketotetrahydrocymenes to the terpenes of the limonene series. The saturated nature of camphor has caused this compound to be regarded as a ketotetrahydrocymene containing a so-called para-linkage (Kannonikow, 3 Bredt 4 ) : — ^Wagner, Ber., 27, 1636. 2Wallach, Ann. Chem., 277, 105. sKannonikow, Journ. Russ. Phys. Chem. Soc, 1, 434. *Bredt, Ann. Chem., 226, 261. INTRODUCTION. 25 According to this, Wallach 1 has gradually brought the follow- ing constitutional formula of pinene into consideration : — CH, During the course of further investigations, however, these for- mulas have proved untenable, and Bredt 2 has proposed the fol- lowing formulas for camphor, pinene and camphene : — CH j CH CI H 3 C-C-CH 3 CH, C C( CHOH CH, M 3 Camphor. CH CH H3C-C-CH3 CH 2 A CH 3 Camphene. CH Bredt's camphor formula interprets the conduct of this com- pound especially well in the formation of trimethylsuccinic acid iWallach, Ber., 24, 1545. 2Bredt, Ber., 26, 3047. 26 THE TERPENES. from camphoronic acid resulting from the oxidation of camphor. The behavior of pinene can be explained with the help of the above formula, if we assume with Bredt that, by the action of certain reagents, especially aqueous acids, the formation of an atomic group C(CH 3 ) 2 may result, by which an isopropyl group is formed, accompanied by a break in the pentamethylene ring. Thus the formation of a hexahydrocymene derivative is made possible. For example, Bredt explains the formation of terpine in the following manner : Whether this formula proposed by Bredt will be proved cor- rect in all points, time alone will tell. Some investigators have already proposed modifications of Bredt's formulas, which seem to better suit certain facts. 1 As a rule, in the present state of our knowledge, criticisms arise against all such formulas. It would, therefore, be too early at this time to pass a critical judgment con- cerning the value of the extremely large number of formulas pro- posed for pinene. Fenchone, which very closely resembles camphor, stands in its relation to the latter, as a meta- to a para-compound (Wallach). Fenchene undoubtedly possesses a similar relation to cam- phene. Aside from the terpenes, C 10 H 16 , already mentioned, two others are known, terpinene and phellandrene, both of which appear to possess but one ethylene linkage. They do not, however, admit of classification in the same group with pinene, camphene and fenchene. Both are without doubt closely allied to cymene. The relations of the terpenes, C 10 H 16 , to the numerous ketones occurring in nature or artificially prepared, and to the monobasic alcohols have now been presented. There remains for conclusion the consideration of a series of polyvalent alcohols known in the terpene series. Several of these alcohols lose water with great readiness, forming anhydrides which possess the character of ox- ides. To these anhydrides belong the saturated cineole, C 10 H 18 O, pinole hydrate, C 10 H 17 O OH, and fenehenole, C 10 H 18 O. CH 3 CH 3 CIL, 0==CH H,C — C — CH, Is CH, C CH 2 Pinene. +2H,0= H 2 C— C(OH)— CH 2 H,C— C(OH)— CH„ CH 3 Terpine. Wagner, Ber., 27, 2270; Tiemann and Semmler, Ber., 28, 1345. INTRODUCTION. 27 After it was recognized that certain terpenes were to be considered as dihydrocymenes, the next step was to synthe- size the latter hydrocarbons, and to identify them with known terpenes. The long familiar reaction by which a terpene, C 10 H 16 , results from heating isoprene to a high temperature, and which Wallach 1 has characterized as dipentene, can be looked upon as the first synthesis of a terpene; the course of the reaction was not, however, clear, and the constitution of isoprene, which had not been prepared by synthetical methods, was not known. After Wallach 2 in the year 1890 had demonstrated that cer- tain unsaturated aliphatic ketones (methyl hexylene ketone, C 8 H 14 0, and methyl heptylene ketone, C 9 H ls O), could easily be converted, by the elimination of water, into lower homologues of the terpenes (dihydro-meta-xylene, C 8 H 12 , and dihydro-pseudo- cumene, C 9 H 14 ), Bertram and Walbaum 3 in 1892 succeeded in accomplishing the partial synthesis of two terpenes, dipentene and terpinene, by the elimination of water from an unsaturated alcohol of the fatty series, linalool, C 10 H 17 OH, which is found in nature. The complete synthesis of a dihydrocymene, C 10 H 16 , was accom- plished in the year 1893 by Baeyer, 4 who distilled the dibromide of methylisopropyl-succino-succinic ester with quinoline. The resultant dihydrocymene, boiling at 174°, has not yet, however, been identified with any known terpene. In this connection it might further be recalled that a ketotetra- hydrocymene, C 10 H 16 O, has been synthetically prepared by Knoe- venagel. 5 This compound, to which Kuoevenagel ascribes the formula CH OC 0 — CH, H 2 C CH, CH L A H,C CH, is derived from isobutylidene diaceto-acetic ester, iWallach, Ann. Chem., 227, 295 and 302. «Wallach, Ann. Chem., 258, 338; 272, 120; Ber., 24, 1573. a Bertram and Walbaum, Journ. pr. Chem., N. F., 601. *Baeyer, Ber., 26, 233. sKnoevenagel, Ber., 26, 1085; Ann. Chem., 281, 44. 28 THE TERPENES. /CH< C ocH 3 (CH 3 ) 2 CH— CH Vr* 121,3°. He also investigated the rotatory power of limonene in different solvents. The specific gravity of levo-limonene at 20° is 0.846, the re- fractive index, n D = 1.47459, corresponding to a molecular re- fraction of 45.23 (Wallach). According to Godlewsky, 6 when limonene tetrabromide (pre- pared from carvene, and melting at 104°), is reduced in alcoholic solution with zinc dust, a limonene is obtained, which, after dry- ing and distilling over sodium, has the following properties : it boils at 177.5° under 759 mm. pressure, has a specific gravity 0.8441 at 20°, anda specific rotatory power, \a] D = + 125° 36', at 20° ; bromine converts it into the original tetrabromide. When treated with perfectly dry hydrogen chloride, limonene yields an optically active monohydrochloride ; with nitrosyl chloride an optically active additive product is formed, and with bromine an active tetrabromide results. If, on the other hand, limonene be treated with hydrogen chloride in the presence of water, it is rendered inactive, and yields dipentene dihydrochlo- ride ; moist hydrogen bromide and iodide act in an analogous man- » Wallach, Ann. Chem., 2^6, 221. "Bertram and Walbaum, Arch. Pharm., 231, 290. 3 Andres and Andrejew, Ber., 1892, 609. ^Wallach and Conrady, Ann. Chem., 252, 144. 5 Kremers, Amer. Chem. Journ., 17, 692. 6 J. Godlewsky and Roshanowitsch, Chem. Centr., 1S99, I., 1241; J. Russ. Chem. Soc, 31, 209. LIMONENE TETEABROMIDE. 73 ner. Limonene is also rendered inactive by heating to high tem- peratures (Wallach 1 ). Limonene tetrabromide, 2 C 10 H 16 Br 4 , is prepared from the fraction boiling at 174° to 176° of the oil of sweet orange peel, or oil from cones of Abies alba. Dissolve the terpene in four times its volume of glacial acetic acid, cool with ice water, and gradually add bromine from a dropping funnel until the liquid no longer absorbs it. Crystals separate at once, and are filtered off with the aid of the pump ; they are pressed on a porous plate, and recrystallized from an equal weight of acetic ether. The yield is about the same as the weight of limonene employed. In regard to the preparation of limonene tetrabromide, com- pare Baeyer and Villiger, 3 and Power and Kleber. 4 Limonene tetrabromide is optically active, and separates in hemihedral rhombic crystals, 6 which melt at 104° to 105°. If hydrobromic acid is eliminated from limonene tetrabromide by heating with alcoholic potassium hydroxide, two molecules of hydrogen bromide are split off, while one bromine atom suffers replacement by one alcohol radical. 6 Thus, if a solution of po- tassium hydroxide in methyl alcohol be employed, the reactions take place in accordance with the following equations : — I. C 10 H 16 Br 4 — 2HBr=Ci 0 H u Br 2 , II. C 10 H u Br 2 +KOCH 3 =C 10 H u BrOCH 3 +KBr. The resulting compound, C 10 H 14 BrOCH 3 , is an oil, which boils at 137° to 140° under 14 mm. pressure, and has a specific gravity of 1.251 and coefficient of refraction, n^ = 1.51963, at 18°. When treated with a solution of hydrogen bromide in glacial acetic acid, this oil gives a quantitative yield of dipentene tetrabromide. If sodium is added to an alcoholic solution of this oil, the atom of bromine in this compound, C 10 H H BrOCH 3 , is re- placed by hydrogen, and carveol methyl ether, C 10 H 15 OCH 3 , is formed. The latter compound is an optically active oil, boiling at 208° to 212°, and has a specific gravity of 0.9065 and coef- ficient of refraction, n^, = 1.47586, at 18°. This carveol methyl iWallach, Ann. Chem., 227, 301. ^Wallach, Ann. Chem., 225, 318; 239, 3; 264, 12; Scheidt, Inaug. Diss., Bonn, 1890. 3 Baeyer and Villiger, Ber., 27, 448; compare Godlewsky, Chem. Zeit., 22, 827. «Power and Kleber, Arch. Pharm., 232, 646. 6 Hintze, Zeitschrift für Krystallographie, 10 [2], «Wallach, Ann. Chem., 281, 127; 264, 12. 74 THE TERPENES. ether is converted into inactive carvone by oxidation with a solu- tion of chromic acid in acetic acid. On the other hand, a conversion of carvone into limonene is said to be accomplished by the following method. 1 Dextro-car- vone is reduced to dihydrocarveol, which is readily converted into methyl dihydrocarvyl xanthate, C 10 H 17 . O • CS 2 . CH 3 ; this substance is a thick oil, and, on distillation, yields two hydrocarbons, boiling at 172° to 173.5° and 174° to 176°, respectively. The higher boiling hydrocarbon may be converted into limonene tetrabromide, which, by the action of zinc dust on its alcoholic solution, yields pure dextro-limonene. A liquid limonene tetrabromide is also known, and is readily formed when bromine is added to the hydrocarbon dissolved in a perfectly dry solvent. 2 Limonene nitrosochlorides, C 10 H 16 NOC1, are known in four modifications; by the action of nitrosyl chloride, dextro- and levo-limonene each yields two optically active isomerides, distin- guished as a- and /9-limonene nitrosochlorides. There are, there- fore, four isomeric, optically active limonene nitrosochlorides, and corresponding to them, are two inactive modifications, the a- and /9-dipentene nitrosochlorides. PREPARATION OF THE NITROSOCHLORIDES FROM DEXTRO- AND LEVO-LIMONENE. 3 To a mixture of five cc. of limonene, seven cc. of amyl nitrite (or eleven cc. of ethyl nitrite), and twelve cc. of glacial acetic acid, well cooled by a mixture of ice and salt, add slowly and in small portions at a time a mixture of six cc. of crude hydrochloric acid and six cc. of glacial acetic acid. Finally add five cc. of alcohol and allow to stand for some time in the freez- ing mixture. A mass of crystals consisting of the crude nitroso- chloride separates, is filtered with the pump and washed with alcohol. One hundred grams of nitrosochloride are obtained from 120 grams of limonene. SEPARATION OF THE a- AND ^-LIMONENE NITROSOCHLOR- IDES. One hundred grams of the white and perfectly dry, crude product are digested with 300 grams of chloroform for a few iL. Tschügaeff, Ber., 33, 735. «Wallach, Ann. Chem., 281, 137. »Wallach, Ann. Chem., 252, 106; 270, 174. LIMONENE NITKOSOCHLORIDES. 75 moments in the cold. It is then filtered, and the crude ß-com- pound remaining on the filter is washed with a little chloroform. An excess of methyl alcohol is added to the filtrate, thus pre- cipitating the a-compound as a crystalline powder. The crude a-nitrosochloride is filtered, dried, and digested in a flask with two to three times its quantity of dry ether for one-quarter of an hour, care being taken to keep the mixture cold. It is then filtered, and the ether allowed to evaporate, when the a-com- pound generally separates in large crystals ; they are rubbed up with methyl alcohol, again dissolved in twice their weight of ether, filtered, and some methyl alcohol is added to the filtrate. By the slow evaporation of the solution, pure a-limonene nitro- sochloride is obtained in large, brilliant crystals, which melt at 103° to 104°. a-Limonene nitrosochloride separates in monoclinic crystals ; together with holohedral forms, hemimorphic crystals are always found, which in the case of the dextro-limonene derivative have the clinodome on the left, while those of the levo-compound have the clinodome on the right. a-Limonene nitrosochloride is soluble at ordinary temperature in one part of chloroform, and in two parts of ether. It quickly decomposes on standing. The crude /?-limonene nitrosochloride is dried and dissolved in ten times its weight of chloroform. The solution is filtered and precipitated with methyl alcohol in such a manner that a further addition of this reagent causes a slight additional pre- cipitate. Thus, the most difficultly soluble portion of the nitro- sochloride is obtained ; it is filtered, washed with ether and dried. The dry substance is again digested with three times its weight of ether, and, on evaporation of this solvent, pure /?-limonene nitrosochloride is obtained ; after drying, this compound forms soft needles, which melt at about 100°. The /3-nitrosochlorides may be kept for a long time without decomposing. The crude limonene nitrosochlorides contain only about twenty per cent, of the /3-nitrosochlorides. (For the influence of the concentration of the hydrochloric acid on the yield of /9-nitrosochlorides, compare experiments of Wallach. 1 ) According to Wallach, 2 the a- and /9-nitrosochlorides are phys- ical, and not chemical isomerides. While Wallach gives them the formula, iWallach, Ber., 28, 1308 and 1474. 2 Wallach, Ann. Chem., 252, 113; 270, 185. 76 THE TEKPENES. Baeyer 1 is inclined to consider these compounds as possessing double that molecular weight, and to regard them as bisnitrosyl- derivatives. Wallach 2 has, however, published the results of ex- periments, which indicate that the a- and /2-nitrosochlorides actu- ally possess twice the molecular weight of the above formula, but in all other relations they both behave as mono-molecular com- pounds. When heated with alcoholic potash, a- and /9-limonene nitroso- chlorides form the same carvoxime, melting at 72°. Benzoyl limonene nitrosochloride, 3 M C 10 H 15 / \NOCOC 8 H 5 is formed by adding one molecule of benzoyl chloride to a solu- tion of one part of a-limonene nitrosochloride in two parts by weight of dry ether and allowing the mixture to stand for one or two weeks. It may also be readily obtained by warming /3-limonene nitroso- chloride with one molecule of benzoyl chloride and eighty times its weight of dry ether for several days on a water-bath. Benzoyl lim- onene nitrosochloride melts at 109° to 110°, is difficultly soluble in ether, easily soluble in acetic ether, and is optically active. It yields carvoxime 4 by boiling with sodium alcoholate. Limonene nitrosobromide, 5 C 10 H 16 . NOBr, is obtained by a method analogous to that used in the preparation of the nitrosochloride. It melts at 90.5°. Limonene nitrosate, 5 /ON0 2 xNOH is an oil, which solidifies only at a very low temperature ; it also yields carvoxime by treatment with alcoholic potassium hydroxide. LIMONENE NITROL AMINES. 6 If dextro-a-limonene nitrosochloride be treated with an organic base, two isomeric nitrolamines are formed, one of which is i Baeyer, Ber., 28, 648. ^Wallach, Ber., 28, 1308 and 1474. »Wallach, Ann. Chem., 270, 175. 4 Wallach, Ber., 28, 1311. 5 Wallach, Ann. Chem., 2J f 5, 258. «Wallach, Ann. Chem., 252, 113; 270, 180. LIMONENE NITRO LANILIDES. 77 optically dextrorotatory and is called a-nitrolamine, the other is levorotatory, and termed ß-nitrolamine. If dextro-/3-limonene nitrosochloride be treated with the same base, exactly the same reaction-products are obtained, namely, a dextrorotatory a-limo- nene nitrolamine, together with a levorotatory /3-limonene nitro- lamine. If, on the other hand, levo-a- or levo-/?-limonene nitrosochloride be treated with an amine, a mixture of a levo- rotatory a- and a dextrorotatory /9-limonene nitrolamine is formed. These a- and /?-nitrol amines have simple molecules (Wallach 1 ). If equal proportions of the two oppositely active a-, or /?-limo- nene nitrolamines are recry stall ized together, the corresponding a- or /9-dipentene nitrolamine is obtained. These may also be prepared together by a precisely analogous method from the a-, as well as from the ß-, dipentene nitrosochloride. The following table may serve to explain these transformations (page 78). 1. Limonene nitrolanilide s, .NOH C 10 H 16 f \NHC 6 H 6 Twenty grams of pure a-limonene nitrosochloride are pulver- ized and warmed with twenty cc. of aniline and thirty cc. of alcohol in a flask fitted with a reflux condenser. The mixture is heated with constant shaking until a reaction commences. After the violent reaction has taken place, the mass is allowed to cool, and treated in the cold with an excess of concentrated hydrochlo- ric acid. The resulting mass of crystals is filtered, and washed with alcohol and ether. These crystals consist of the hydrochloric acid salt of a-limonene nitrolanilide. The free a-base is obtained by treating the hydrochloride with ammonia. a-Limonene nitrol- anilide crystallizes from alcohol in monoclinic crystals, which melt at 112° to 113°. The yield of the a-base is about eighty per cent, of the theoretical. In order to obtain the /?-anilide, the alcholic-acid filtrate from the hydrochloride of the a-base is poured into a large excess of ammonium hydroxide. The /?-anilide gradually solidifies, and is dissolved in three times its weight of benzene in order to remove any aniline which may cling to it. Most of the /?-anilide sepa- rates from this solution on cooling, while the remainder may be precipitated by the addition of petroleum ether. /9-Limonene nitrolanilide crystallizes from alcohol in moss-like needles, which melt at 153°. It is difficultly soluble in ether, readily soluble in chloroform. »Wallach, Ber., 28, 1311. THE TERPENES. LIMONENE NITROLBENZYLA MINES. 79 When the glacial acetic acid solution of the a-, or the hydro- chloric acid solution of ß-, limonene nitrolanilide is treated with a solution of sodium nitrite, nitroso-compounds, /NOH Ci 0 H 15 < \N(NO)C 6 H 6 are formed. The oc-nitroso-compound melts at 142°, while the /9-derivative, characterized by its great power of crystallization, melts at 136°. 2. Limonene nitrolpiperidides, Ci 0 H 15 / \nc 5 h 10 Twenty grams of pure pulverized a-limonene nitrosochloride are covered with twenty grams of piperidine and sixty grams of alcohol, and gently warmed with frequent shaking. When a clear solution is obtained, the warm liquid is poured into an evaporat- ing dish and a small quantity of water added. On cooling, cry- stals of the very sparingly soluble, impure /?-base separate. These are filtered, and the readily soluble, impure «-base is pre- cipitated from the filtrate by water. The purification of these compounds is based on the circumstance that the /9-piperidide is sparingly, the ec-base extremely easily, soluble in petroleum ether. The crude a-base is first dissolved in acetic acid, filtered to remove the non-basic impurities, and again thrown out with am- monia. It first appears as an oil which solidifies after a little time. It is dried, digested with a small amount of petroleum ether, decanted from the undissolved /5-base, and, after evapora- tion of the petroleum ether, is recrystallized from alcohol. a-Limonene nitrolpiperidide separates in orthorhombic crystals, and melts at 93° to 94°. The crude /9-base is dried, digested with cold petroleum ether, and the undissolved portion recrystallized from warm petroleum ether with the addition of some methyl alcohol. /9-Limonene nitrolpiperidide melts at 110° to 111°. 3. Limonene nitrolbenzylamines, C 10 H 18 f \nhch 2 c 6 h s Two bases are formed by the action of limonene nitrosochloride on benzylamine ; only the a-amine, however, has been obtained in a condition of purity. It forms hard needles, melting at 93°. 80 THE TERPENES. This base yields a nitrate, which forms splendid crystals, and is very sparingly soluble in water. Emil Fischer 1 and other investigators have suggested that the isomerism of the a- and /9-limonene nitrolamines is to be explained as stereo-chemical isomerism. According to Wallach, 2 however, the known facts do not determine whether the a- and /3-limonene nitrolamines, in contrast to the nitrosochlorides, have the same or different chemical structure. The following observations argue against the stereo-chemical theory. 2 1. No transformations of the a- into the /9-limonene nitro- lamines, or the ß- into the «-derivatives, have yet succeeded. 2. a-Limonene nitrolanilide is a weaker base than /9-limonene nitrolanilide. 3. On heating, the a-anilide yields aniline and a product con- taining carvoxime ; the /9-anilide, under the same circumstances, gives aniline and an isonitrile. 4. a-Limonene nitrolanilide in a methyl alcohol solutionis cap- able of adding the elements of hydrochloric acid, forming a com- pound which melts at 115°. The latter substance is apparently identical with hydrochlorolimonene nitrolanilide, .NO C M H W CI<( \NH.C 6 H S obtained from hydrochlorolimonene nitrosochloride. Under the same conditions, /9-limonene nitrolanilide forms a compound, C 16 H 23 C1N 2 0, which melts at 78° ; a substance similar to this compound has not yet been prepared from hydrochlorolimonene nitrosochloride. It should be noted that a- and /9-limonene nitrolanilides possess the same molecular weight (determined by the boiling point method, dry ether being the solvent). Limonene hydrochloride, C 10 H 16 ■ HCl. Limonene, well dried over metallic sodium, is diluted with an equal volume of perfectly dry carbon bisulphide, and saturated with dry hydrochloric acid gas. The liquid must be well cooled with ice, and every precaution used to avoid the presence of any trace of water. One hundred grams of limonene require twenty-four hours for the saturation. When this point is reached, the excess of hydrochloric acid and carbon bisulphide is removed lEmil Fischer, Ber., 23, 3687 ; 2J h 2G8G. »Wallach, Ann. Chem., 270, 186. HYDROCHLOROLIMONENE NITROSATE. 81 by distillation under diminished pressure, and the resulting limo- nene monohydrochloride rectified in vacuum (Wallach, Kremers 1 ). Optically active limonene hydrochloride forms a colorless oil, boiling at 97° to 98° under 11 mm. to 12 mm. pressure. A product obtained from dextro-limonene had the specific gravity of 0.973 at 17.8°, while that obtained from levo-limonene had the specific gravity of 0.982 to 16°. 1 Limonene hydrochloride appears to readily change into an in- active modification on standing. This transformation is accom- panied by polymerization of the substance. Although limonene hydrochloride (like its inactive modification, dipentene hydrochloride) behaves as a saturated compound to- wards dry hydrochloric acid, it unites with the halogens, nitrosyl chloride, etc., forming additive compounds. When allowed to remain in contact with water in a sealed glass tube for some months, limonene hydrochloride forms crystals of terpine hydrate. Alcoholic potassium hydroxide eliminates the elements of hydrogen chloride from limonene hydrochloride. In an acetic acid solution it unites with hydrochloric acid, forming dipentene dihydrochloride, while under the same conditions, hydrogen bromide converts it into a compound melting at 47° to 48°. According to a preliminary notice by Semmler, 2 the chlorine atom in limonene hydrochloride can be replaced by a hydroxyl- group, thus forming an optically active terpineol. Hydrochlorolimonene nitrosochloride, C 10 H 17 C1 • NOC1, is obtained by the gradual addition of twenty-five cc. of a five to six per cent, solution of hydrochloric acid in glacial acetic acid to a well cooled mixture of five cc. of limonene hydrochloride, ten cc. of methyl alcohol and seven and one-half cc. of amyl nitrite. Water is then added until the liquid commences to appear cloudy, when the nitrosochloride separates gradually. It is purified by dissolv- ing in chloroform and precipitating with methyl alcohol. It melts at 109° (Wallach 3 ). Hydrochlorolimonene nitrosate, 3 C 10 H 17 C1 • NO(ON0 2 ), is pre- pared by treating a very cold mixture of one molecule of limonene hydrochloride and one molecule of amyl nitrite with one molecular proportion of sixty per cent, nitric acid. The mixture should be agitated during the addition of the nitric acid. The nitrosate separates as a white, crystalline precipitate. The yield can be increased by the final addition of alcohol. Hydrochlorolimonene 1 Wallach and Kremers, Ann. Chem., 270, 188. Temmler, Ber., 28, 2189. sWallach, Ann. Chem., 2^5, 260. 6 82 THE TERPENES. nitrosate was first obtained by Maissen 1 ; its constitution was ex- plained by Wallach's investigation. It melts at 108° to 109°. Hydrochlorolimonene nitrolamines, C 10 H 17 C1<( /NO NHR Hydrochlorolimonene nitrosate is best employed for the prepara- tion of these compounds, since it is more difficultly soluble, and more readily obtained than the corresponding nitrosochloride ; the following general observation, however, should be noted in prepar- ing these amines. It has been mentioned that limonene hydro- chloride is readily converted into the inactive modification. Con- sequently, some inactive hydrochlorodipentene nitrosate is often obtained during the preparation of hydrochlorolimonene nitrosate. If the preparation of the active hydrochlorolimonene nitrola- mines be desired, the most soluble portions of hydrochlorolimonene nitrosate, prepared according to method described, are employed, since hydrochlorodipentene nitrosate is more difficultly soluble than the active modifications, and separates out before the active derivatives (Wallach 2 ). Hydrochlorolimonene nitrolbenzylamine , 2 .NO CjoH 1 ,Cl<' \nhch 2 c 6 h 6 is prepared by warming a mixture of five parts of hydrochloro- limonene nitrosate, ten parts of alcohol and four parts of benzyl- amine for a short time, until the reaction begins. The inactive dipentene base separates in fine needles on cooling. The active base is precipitated from the filtered solution by the addition of water. It is very readily soluble in alcohol, ether and benzene, only sparingly soluble in cold petroleum ether from which it is recrystallized. It is optically active, melts at 103° to 104°, and yields an optically active hydrochloride, which crystallizes from alcohol in fine needles, melting at 163° to 164.° Hydrochlorolimonene nitrolanilide, 2 NO C 10 H 17 C1<( \nhc s h 5 is conveniently prepared by the following method. Three and one-half cc. of aniline are added to a warm solution of five grams 'Maissen, Gazz. Chim., IS, 99. «Wallach, Ann. Chem., 270, 191. OXIDATION PRODUCTS OF LIMONENE. 83 of hydrochlorolimonene nitrosate in thirty-five grams of benzene. Aniline nitrate is formed, and after a few minutes is filtered off ; small quantities of inactive hydrochlorodipentene nitrolanilide separate with the aniline nitrate. To obtain the hydrochlorolimonene nitrolanilide, the benzene filtrate is shaken with hydrochloric acid. The hydrochloride of the nitrolanilide separates as a solid, while the excess of aniline is taken up by the hydrochloric acid solution, and other impuri- ties are dissolved in the benzene. The filtered hydrochloride is rubbed up with ammonium hydroxide, and the free nitrolamine crystallized from alcohol. Hydrochlorolimonene nitrolanilide melts at 117° to 118°. A compound, ^ C 10 H 17 Cl/ / \NHC 6 H 5 obtained by the addition of hydrogen chloride to limonene nitrol- anilide, melts at 115° ; it has not been determined with certainty whether this compound is identical with hydrochlorolimonene nitrolanilide. 1 When hydrochlorolimonene nitrolanilide is treated with alco- holic potash, tarry products are obtained from which no bases free of chlorine have yet been separated in a crystalline condition. (Compare with dipentene derivative, page 97.) The condensation-product, 2 C 10 H 18 O, is produced by heating limonene and paraformaldehyde in alcoholic solution in a closed tube, at 190° to 195°, for several hours; it is a colorless liquid, boils at 246° to 250°, has the specific gravity 0.9568 at 20°, and its optical rotation corresponds to that of the limonene employed. Its acetyl derivative boils at 259° to 263°. The action of nitrous fumes on dextro-limonene cooled by ice and salt gives rise to an alcohol, limonenol, 3 C 10 H 15 OH. OXIDATION PRODUCTS OF LIMONENE. The earlier publications 4 regarding the oxidation of limonene state that a chromic acid mixture converts limonene into carbonic anhydride, acetic acid, and a liquid camphor, C 10 H 16 O, but that nitric acid oxidizes it to oxalic acid and hesperic acid, C 20 H 26 O 17 + 2H 2 0. Tilden and Williamson 5 showed that when 'Wallach, Ann. Chem., 270, 187 and 194. 20. Kriewitz, Ber., 32, 57. »P. Genvresse, Compt. rend., 132, 414. * Wright, Jahresb. Chem., 1873, 369 ; Sauer and Grünling, Ann. Chem., 208, 75. «Tilden and Williamson, Journ. Chem. Soc., 63 (1893), 293; 53 (1888), 880. 84 THE TEEPENES. this terpene is oxidized with nitric acid, neither toluic acid nor terephthalic acid is formed. G. Wagner 1 obtained a tetrahydric alcohol, limonetrol, C 10 H 16 - (OH) 4 , by the oxidation of limonene with potassium perman- ganate. According to Godlewski, 2 oxyterpenylic acid, C 8 H 12 0 5 , is pro- duced, when limonene, free from carvone, is oxidized with potas- sium permanganate ; it melts at 174.5°, and is identical with the acid obtained by Best 3 in the oxidation of carvone with perman- ganate. The dilactone of the acid, C 8 H 10 O 4 , melts at 129° to 130°, and is reconverted into oxyterpenylic acid by the action of potassium hydroxide. Semmler 4 has suggested that those terpene derivatives which contain a double linkage between the nucleus and the side chain shall be termed pseudo-derivatives, and the isomeric compounds containing the double bond in the nucleus, o/^/io-derivatives. In accordance with this suggestion, limonene, which is regarded as having the formula, iG. Wagner, Ber., 1S90, 2315. 2 J. Godlewsky, Chem. Centr., 1899 (I.), 1241; Journ. Russ. Chem. Soc., SI (1899), 211. 30. Best, Ber., 27, 1218. «F. Semmler, Ber., 88, 1455. should be called ortho-limonene. The isomeric, pseudo-limonene, would have the formula, H 3 C CH 2 DIPENTENE. 85 Semmler thinks that it is not improbable that dipentene has the latter formula, and that it is not an inactive modification of limo- nene, as is generally assumed. He further states that both com- pounds would yield the same derivatives by the action of halogen acids. (In a subsequent investigation Semmler 1 concludes that terpinene is to be regarded as pseudo-limonene.) It should also be mentioned that Baeyer 2 has succeeded in con- verting certain monocyclic terpenes into corresponding derivatives of benzene. Thus, limonene is converted into dipentene dihydro- bromide by treatment with a glacial acetic acid solution of hydro- gen bromide ; the dry dihydrobromide is added to bromine, some iodine being introduced, and the mixture allowed to stand until no further evolution of hydrogen bromide is noticed. On treat- ing the product with an alcoholic solution of hydrochloric acid and zinc dust, and then with sodium and alcohol, para-cymene is obtained. The values for the rotatory powers of the limonene derivatives are given in the following table. These values were obtained in the extended investigations of Wallach, Conrady and Kremers. The dextro- and levo-limonene derivatives agree completely in their power of rotation, provided they are obtained in a pure con- dition. A reversal in the direction of rotation takes place when salts are prepared from basic compounds, when limonene nitro- sochloride is converted into carvoxime, and when /9-nitrolamines are formed from the nitroso chlorides ; the a-nitrolamines, which are formed together with the /3-nitrolamines, rotate the plane of polarized light in the same direction as the original nitrosochlo- rides. 4b. DIPENTENE. Dipentene is the optically inactive modification of limonene and bears the same relation to the latter as racemic acid to the optically active tartaric acids (Wallach). Dipentene is widely distributed in many ethereal oils, and is also formed by heating different terpenes and polyterpenes to a high temperature. According to its source, it has been described under various names, such as di-isoprene, terpilene, caoutchin, cinene, cajeputene, isoterebentene, etc. Wallach 3 showed, how- ever, that all these substances contain dipentene as their principal constituent, and are, therefore, to be regarded as identical. Temmler, Ber., 34, 708. «Baeyer and Villiger, Ber., 31, 1401. »Wallach and Brass, Ann. Chem., 225, 309; Wallach, Ann. Chem., 225, 314; 227, 293. THE TERPENES. 9 6 * « 3 •< "55 - . y a T3 , Ol £ "'S ^ -hOO M 3+7 o o o o o to co co o h ONH-*o I— I CO CM t-H ooooooooooooo NMOiOooOtOOOOTfiOO OlCOlNN-^OONlOOOJCOOCO ooo-*cocoa3ooco^<»eO'*rt< + +++++ + I ++ I 4- o o o o lO CO ^ CM rH O t- --I O rH CON H OOOOOOOOOOOOO NMNOOOOfOOOOrlOO COHOOtDHtOOOtOONlOM 1 CNt^I^I^ÖcÖaii-Sair-HOioit^ OCO-"#eOtO«SOOOOSOlOCOCO-'* + + I ++++++ 3* 41 jd *C o o : a> : 03 o o ns E rt< S3 -13 13 *> 3 is o q a> a> ö a a> a> C ö a CD Ö ö C cj o d a On § a o J ° 0) S a> a>.H 5-5 m grsrs a a a .3 J* es ^ ■-J Ö 0) 0> N N N** .pH «i H M c £ e a fl -g g 2 "fl a> a> a> a> a> o ai a ö b c a O J) 1) dl » ■ c c c a a y o o o o o .§ s a a a a a *ö O *fi as o O -d e s a -da >-> o -d ^ a §3 'S § § Ohl W DIPENTENE. 87 Dipentene is contained in camphor oil, 1 Russian 3 and Swedish turpentine oil, 2 oil of pine needle from Picea excelsa, 3 oil of cubebs, oil of limetta leaf, oil of kesso-root, oil of olibanum, 4 oil of mace, 4 oil of wormwood, 1 oil of bergamot, oil of fennel, oil of kuromoji, 5 oil of myrtle, oil of pepper, oil of cardamom, oil of nut- meg, oil of golden rod, oil of massoy bark, oil of thyme (from Thymus capitatus), and oil of wormseed. It is always formed when terpenes are heated to high tempera- tures, hence it is found in Russian and Swedish turpentine oils, 2 as well as in the products of the distillation of pine roots and fir- wood. 6 Dipentene is also obtained from the distillation products of vegetable resins, as copal resin, soft Elemi resin and colo- phonium. 7 Essence of resin also contains dipentene as shown by Renard's 8 experiments, which will be mentioned later. Dipentene is produced under various conditions from many compounds of the terpene series. It is formed, together with higher boiling polymerides, by heating isoprene, 9 C 5 H g , at 250° to 270° ; it is also found with isoprene in the products of the dry distillation of caoutchouc. 10 Pinene is converted into dipentene by heating to 250° to 270°." Dipentene is obtained by mixing equal quantities of dextro- and levo-limonene ; 11 limonene also be- comes inactive by heating to high temperatures. A transforma- tion of pinene into dipentene may also be effected by the action of dilute, or alcoholic, sulphuric acid. Dipentene is derived from many oxidized compounds of the terpene series by the elimination of water. According to Wal- lach and Brass, 13 cineole, C 10 H 18 O,may be converted into dipentene by heating with hydrochloric acid gas, or by heating with ben- zoyl chloride, or by an indirect method depending on the forma- tion of dipentene dihydriodide from cineole and hydriodic acid ; by elimination of hydrogen iodide from this dihydriodide, dipentene is prepared. Terpine hydrate gives dipentene on warming with iWallach, Ann. Chem., 227, 296. "Wallach, Ann. Chem., 230, 244 and 246. sBertram and Walbaum, Arch. Pharm., 231, 290. 'Wallach, Ann. Chem., 252, 100. sKwasnick, Ber., 24, 81. «Aschan and Hjelt, Chem. Ztg., 18, 1566. 'Wallach and Rheindorf, Ann. Chem., 271, 310. sRenard, Ann. Chim. Phys. (6), 1, 223. »Wallach, Ann. Chem., 227, 295; Bouchardat, Compt. rend., 89, 1217. "Wallach, Ann. Chem., 227, 295; Bouchardat, Compt. rend., 80, 1446; 89, 1217; Tilden, Journ. Chem. Soc.,1884 (45), 410; Jahresb. Chem., 1882,405. n Wallach, Ann. Chem., 2^6, 225. « Wallach, Ann. Chem., 227, 289. "Wallach, Ann. Chem., 230, 255. 88 THE TERPENES. acid potassium sulphate, 1 or by boiling with a twenty per cent, phosphoric acid solution. Terpineol, C 10 H 17 OH, yields dipentene when heated with acid potassium sulphate. 2 Of especial interest is the formation of dipentene from linalool ; according to Bertram and Walbaum, 3 the action of formic acid,' sp. gr. 1.22, converts linalool, an unsaturated, optically active,' aliphatic alcohol, into dipentene and terpinene. All these methods of preparation of this terpene yield an impure product. In order to obtain chemically pure dipentene, the halo- gen hydride addition products are employed, the dihydrochloride being particularly well adapted. Hydrochloric acid may be eliminated from this substance by boiling with aniline, 4 or better with sodium acetate. Preparation. 5 — One part by weight of dipentene dihydro- chloride is boiled with one part of anhydrous sodium acetate and two parts of glacial acetic acid for half an hour in a flask provided with a reflux condenser. The product is distilled with steam^ the volatile oil separated and boiled for some time with potassium hydroxide ; it is then redistilled with steam, dried and purified by fractional distillation (Wallach). .Properties. — Since dipentene is inactive limonene, the boiling points of both compounds, when pure, are the same. The biblio- graphical references, however, give the boiling point of dipentene rather higher than that of limonene. These differences are to be traced to the varying degrees of purity of the hydrocarbons. Wallach found the boiling point of dipentene, prepared from the dihydrochloride by means of aniline, to be 178°; it had the specific gravity of 0.845 at 20° and the refractive index, n = 1.47308. 6 A relatively pure dipentene, prepared by the dry distillation of caoutchouc, boils at 175° to 176°, has the sp. gr. 0.844 and the refractive index, n^ = 1.47194, at 20° (Schimmel & Co.). According to Tilden and Williamson, 7 dipentene, obtained from the dihydrochloride by the action of aniline, contains cymene, ter- pinene, terpinolene and a saturated hydrocarbon similar to paraffin; when oxidized with nitric acid it gives a considerable quantity of toluic acid. i Wallach, Ann. Chem., 230, 255. »Wallach, Ann. Chem., 275, 104; 291, 342. 3 Bertram and Walbaum, Journ. pr. Chem., N. F., 45, 601. * Wallach, Ann. Chem., 227, 286; 245, 196. 5 Wallach, Ann. Chem., 239, 3. «Wallach, Ann. Chem., 245, 197. »Tilden and Williamson, Journ. Chem. Soc, 1893 (63), 292. DIPENTENE DIHYDROCHLORIDE. 89 Dipentene polymerizes at high temperatures without previous conversion into an isomeric terpene. It is, therefore, characterized by its relative stability ; but, nevertheless, it may be changed into terpinene. 1 This transformation into terpinene, accompanied by a consider- able polymerization of the terpene, takes place when dipentene is warmed with alcoholic sulphuric acid. Further, if dipentene dihydrochloride be boiled with alcohol for some time, terpinene is produced by the withdrawal of hydrochloric acid. These reactions indicate that terpinene, which is always obtained together with dipentene by boiling terpine hydrate or terpineol with concen- trated mineral acids, is a secondary product, resulting from the dipentene primarily formed. On shaking with an equal volume of concentrated sulphuric acid, dipentene is converted into cymeme sulphonic acid and cymeme, with evolution of sulphur dioxide ; cymene also results by the action of phosphorus pentasulphide on dipentene. The following derivatives of dipentene, without exception, may be prepared not only from dipentene, but also by combining equal parts by weight of the corresponding dextro- and levo-limonene derivatives. Dipentene hydrochloride, 2 C 10 H 16 . HCl, is obtained by the same method as limonene hydrochloride ; it is likewise formed when equal volumes of dextro- and levo-limonene hydrochlorides are mixed (Wallach 3 ). This compound, like its active components, is not changed by dry hydrogen chloride ; with moist hydrochloric acid, it forms dipentene dihydrochloride. It forms additive products with bromine, nitrosyl chloride, etc. It is only distinguished from limonene hydrochloride by its lack of optical activity. Dipentene dihydrochloride, C 30 H 16 . 2HC1, is formed by the action of moist hydrochloric acid on numerous compounds of the terpene series which are related to dipentene. It is obtained by satu- rating the alcoholic, ethereal or acetic acid solution of dipentene, and also of pinene and limonene, with hydrochloric acid gas. It further results by the action of hydrochloric acid on terpine hydrate, terpineol and cineole. In order to prepare dipentene dihydrochloride, dilute limonene with one-half its volume of glacial acetic acid, and pass a current of hydrochloric acid gas over, not into, the well cooled liquid, with frequent shaking. Every rise in temperature of the liquid, which would lead to the formation of oily by-products, may thus 1 Wallach, Ann. Chem., 2S9, 15. zWallach, Ann. Chem., 245, 247; 270, 188. 3Wallach, Ann. Chem., 270, 189; 245, 247; Riban, Jahresb. Chem., 1874, 397; Bouchardat, Bull. Soc. Chim., 24, 108. 90 THE TERPENES. be prevented. As soon as the mass becomes solid, shake with water, filter, press on a porous plate, and purify the product by dissolving in alcohol and precipitating with water (Wallach *). Dipentene dihydrochloride melts at 50°, and boils at 118° to 120° under a pressure of 10 mm. 2 It is easily soluble in alcohol, ether, chloroform, ligroine, benzene, and glacial acetic acid. Its conversion into dipentene, as well as its transformation into ter- pinene by boiling with alcohol, has already been mentioned ; on standing with alcohol, terpine hydrate is formed. The products of the action of sodium, and sodium ethylate on this compound have been investigated by Montgolfier, 3 and Tilden. 4 By warm- ing with a little ferric chloride solution, dipentene dihydrochlo- ride gives a rose color, which passes into a violet-red and finally into a blue (Eiban). This dipentene dihydrochloride belongs to the = + 73.74°. Considerable amounts of an oily tetrabromide are always formed, together with the solid compound ; this is probably the reason why sylvestrene can not be separated in the form of its tetrabromide from mixtures of sylvestrene and other ethereal oils. Sylvestrene nitrosochloride, C 10 H 16 • NOC1, is prepared from pure sylvestrene, obtained from its dihydrochloride, by the follow- ing method. To a well cooled mixture of four cc. of the terpene and six cc. of amyl nitrite, four cc. or five cc. of fuming hydro- chloric acid are added with constant agitation. When the heavy oil which separates is shaken with a little ethyl alcohol, it solidifies to a crystalline mass. It is purified by dissolving in a small quantity of chloroform and precipitating with petroleum ether ; the product is then recrystallized from methyl alcohol. It melts at 106° to 107°, and is dextrorotatory (Wallach 2 ). Sylvestrene nitrolbenzylamine, .NO X NHCH 2 C 6 H 5 is obtained by warming an alcoholic solution of sylvestrene nitro- sochloride with benzylamine (Wallach 3 ). The base separates from methyl alcohol in well defined crystals, melting at 71° to 72°. It has a specific rotatory power, [a]i> = + 185.6°, while that of its hydrochloride is [a] D = + 79. 2°. 4 Wallach, Ann. Chem., 239, 28. .äWallach, Ann. Chem., 245, 272. *:*yVallä<$' Amn. Chem., 252, 135. \JWaljäctijän£ Conrady, Ann. Chem., 252, 150. CARVESTRENE. 103 According to Baeyer, 1 sylvestrene may be converted into meta- cymene by a method similar to that employed in the conversion of limonene into para-cymene. Dry sylvestrene dihydrobromide is brominated by bromine in the presence of iodine, and the resulting product is reduced with zinc dust and alcoholic hydrochloric acid, and finally with sodium and alcohol ; a hydrocarbon is obtained, which, when freed from unsaturated compounds by the action of potassium permanganate, is identical with meta-cymene. 6. CARVESTRENE. This optically inactive terpene was obtained by Baeyer 2 in the distillation of carylamine hydrochloride and vestrylamine hydro- chloride. Since it has no rotatory power, and yields the sylves- trene reaction, Baeyer regards it as inactive sylvestrene. Its similarity with sylvestrene and its formation from a carvone de- rivative suggested the name carvestrene. Wallach 3 obtained dihydrocarvone, C, 0 H 16 O, by the oxidation of dihydrocarveol ; subsequently, Baeyer 4 prepared the same com- pound by the reduction of carvone. Dihydrocarvone is converted into the isomeric ketone carone, C 10 H 16 O, by the successive ad- dition and removal of hydrobromic acid (Baeyer 5 ). When the oxime of this optically active carone is reduced with sodium and alcohol, it yields an active base carylamine, which in turn may be changed into the hydrochloride of an isomeric, but optically inactive, base, vestrylamine, 2 C 1() H 17 NH 2 , by heating with hydro- chloric acid. When vestrylamine hydrochloride 2 is distilled in an atmos- phere of dry hydrochloric acid gas, it decomposes into ammonium chloride and a hydrocarbon, C 10 H 16 , whilst carylamine hydrochlo- ride, under the same conditions, partially volatilizes without change, but a little of it is converted into vestrylamine hydrochloride, which then yields the same hydrocarbon ; the latter consists of crude carvestrene : C J0 H 17 NH 2 HCl = NH 4 C1 + C 10 H ]6 . The impure carvestrene is boiled for half an hour with fused sodium acetate and glacial acetate acid in order to destroy ad- "Baeyer and Villiger, Ber., 31, 2067. «Baeyer, Ber., 27, 3485. sWallach, Ann. Chem., 275, 115; 279, 378. «Baeyer, Ber., 26, 823. sBaeyer, Ber., 27, 1919. 104 THE TERPENES. mixed hydrochlorides. The resultant terpene boils at 180° to 186°, and gives the sylvestrene reaction (the addition of a drop of concentrated sulphuric acid to a solution of one drop of the terpene in one or two cc. of acetic anhydride produces a blue coloration). The product is then dissolved in glacial acetic acid, treated with an acetic acid solution of hydrogen bromide, and allowed to re- main at a low temperature for forty-eight hours, since the addi- tion of hydrobromic acid to carvestrene takes place very slowly. The reaction-mixture is poured onto ice ; the resulting crystals are filtered, pressed on a plate and purified by recrystallizing from ether, to which a little glacial acetic acid is added. The dihy- drobromide is readily soluble in ether, more sparingly in glacial acetic acid. Pure carvestrene is formed by distilling the dihydrobromide with four parts of quinoline, and shaking the distillate with dilute sulphuric acid; the terpene remains undissolved, and is rectified over sodium. Properties. 1 — Carvestrene has an odor somewhat like that of dipentene ; it boils at 178° (corr.), and is optically inactive. Baeyer gives no statements relative to its specific gravity. It rap- idly becomes resinous on exposure to air, and then smells like tur- pentine oil. It decolorizes potassium permanganate at once, and, like terpinene, is oxidized by chromic acid in the cold. It has al- ready been suggested that since carvestrene gives the sylvestrene reaction, it is perhaps to be regarded as the optically inactive mod- ification of sylvestrene. According to Semmler, 2 the crude carvestrene, boiling at 180° to 180°, obtained by the elimination of ammonia from vestry- lamine, probably contains some pseudo-carvestrene ; while the pure terpene, boiling at 178°, prepared by heating the dihydrobromide with quinoline, is to be regarded as the true ortho-carvestrene. Carvestrene dihydrochloride, C UI H I6 ■ 2HC1, is prepared by treat- ing pure carvestrene (regenerated from the dihydrobromide) in a glacial acetic solution with hydrogen chloride, and, after stand- ing for twenty-four hours, pouring the product onto ice. The heavy oil which separates solidifies on the addition of an ex- tremely small crystal of the dihydrobromide. It crystallizes from glacial acetic acid in long prisms, and melts at 52.5°. Carvestrene dihydrobromide, C 10 H 16 ■ 2HBr, obtained by the method given above, crystallizes in well formed, rhombic tablets whose solid angles are truncated. These crystals may be easily t Baeyer, Ber., 27, 3490. sSemmler, Ber., 34, 708. TERPIXOLENE. 105 distinguished from those of the isomeric dipentene dihydrobro- mide. 0 Carvestrene dihydrobromide melts at 48° to 50°, and is more readily soluble than dipentene dihydrobromide. By the action of silver acetate and glacial acetic acid on the dihy- drobromide, a terpine results, which melts at 127° and crystallizes in splendid, flat, rhombic pyramids. Baeyer 1 has also succeeded in converting carvestrene into meta- cymene by the bromination of carvestrene dihydrobromide, and subsequent reduction with zinc and hydrochloric acid, and finally with sodium and alcohol. 7. TERPINOLENE. Terpinolene is one of the terpenes which have not ^ yet been found in nature. It was discovered, and characterized as a chemical individual, by Wallach 2 in 1885. He showed that when turpentine oil is heated with alcoholic sulphuric acid, according to Flawitzky's 3 method, a terpene is formed, which had hitherto been overlooked. According to further observations 4 of Wallach, terpinolene is obtained by boiling terpine hydrate, terpineol or cineole with dilute sulphuric acid or phosphoric acid. In all these reactions, terpinene and other products are formed ; among the latter, cymene should be especially noted as it results whenever the sulphuric acid method is employed. Wallach and Kerkhoff 5 found that solid terpineol (m. p. 35°) is remarkably well ad- apted for the preparation of terpinolene, and that the formation of by-products can be prevented by using a solution of oxalic acid for the removal of the elements of water ; however, it is well to boil for a short time only, since otherwise a conversion into terpinene results. Terpinolene may also be prepared with great facility by dissolving terpineol in anhydrous formic acid, and gently heating the liquid for a few miniites, when terpinolene separates rapidly. 6 According to' Baeyer, 7 terpinolene is formed from the tribro- mide, C 10 H 17 Br 3 (m. p. 110°), which is derived from dipentene dihydrobromide by bromination. This tribromide is converted into the acetate of J-4(8)-terpen-l-ol, an alcohol melting at 69° iBaeyer and Villiger, Ber., 31, 1402. ^Wallach, Ann. Chem., 227, 283; 280, 262. »Flawitzky, Ber., 12, 1022. 'Wallach, Ann. Chem., 239, 23. «Wallach and Xerkhoff, Ann. Chem., 275, 106. e Wallach, Ann. Chem., 291, 342. ^Baeyer, Ber., 27, 436. 106 THE TERPENES. to70°, by the action of zinc dust and glacial acetic acid, and when this acetate is distilled with quinoline, terpinolene results : C 10 H 17 OCOCH 3 — CH 3 COOH = C 10 H 16 . Baeyer expresses these transformations by the following formulas: 9 H 3 CH. ,C CH 2 ^OCO CBr H 3 C CH 3 Tribromide (m. p. 110°). C A H,C CH 3 A*(8)_Terpen-l-ol acetate. Uß CH 3 Terpinolene. H 3 C CH S Terpineol (m. p. 35 c It is worthy of notice that terpinolene tetrabroniide may be converted into terpinolene by treatment with zinc dust and glacial acetic acid. Preparation. 1 — Melted terpineol (m. p. 35°) is added drop by drop to a boiling solution of oxalic acid (one part of acid to two parts of water) through which a current of steam is passing. The addition of the terpineol is so regulated that one gram is introduced every minute, thus accomplishing the decomposition almost completely, while the resulting terpinolene is at once re- moved from the action of the acid by means of the steam distilla- tion. The oil so obtained is distilled in vacuum, since terpinolene is partially changed by distillation at ordinary pressure. A purer product is obtained by treating terpinolene tetrabro- mide with zinc dust and glacial acetic acid at a low temperature. Properties. — Terpinolene is an optically inactive hydrocarbon whose physical constants have not been determined because its in- stability prevents the preparation of a chemically pure product. 1 Wallach and Kerkhoff, Ann. Chem., 275, 106; Baeyer, Ber., 27, 448. TERPINOLENE TETRABROMIDE. 107 According to Wallach/ it boils between 185° and 190°. Baeyer states that terpinolene prepared from the tetrabromide boils at 75° under 14 mm. pressure j on distilling under the or- dinary pressure it boils at 183° to 185° (corr.), but by continued boiling for ten minutes in a flask connected with reflux condenser, terpinolene is changed into a thick oil which no longer gives the crystalline tetrabromide. It is very sensitive toward acids, being converted into a prod- uct which consists largely of terpinene. A solution of terpinolene in glacial acetic acid absorbs hydro- chloric or hydrobromic acid, producing dipentene dihydrochloride or dihydrobromide. 1 Terpinolene dibromide, C 10 H lg Br 2 .— Baeyer 2 obtained this com- pound from terpinolene (regenerated from the tetrabromide by means of zinc dust) by adding two atoms of bromine to the hydro- carbon dissolved in a mixture of alcohol and ether. On evapora- tion of the solution, the dibromide separates in beautiful prisms, which melt at 69° to 70°. When the glacial acetic acid solution of terpinolene dibromide is treated with hydrobromic acid, the same tribromide (1, 4, 8- tribromoterpane, m. p. 110°) results which Wallach obtained hy the bromination of dipentene dihydrobromide. This tribromide is further identified by its conversion into the characteristic, blue nitrosochloride of z/-4-(8)-terpen-l-ol acetate, melting at .82° (Baeyer 2 ). Terpinolene tetrabromide, C 10 H 16 Br 4 , was first prepared by Wal- lach by brominating terpinolene in a glacial acetic acid solution at a low temperature. 3 According to Baeyer and Villiger, 4 it is better to dilute crude terpinolene in portions of ten grams or less with an equal volume of amyl alcohol and twice its volume of ether, and then to add bromine to the well cooled mixture. After evap- oration of the ether, the tetrabromide crystallizes in voluminous leaflets. Optically inactive terpinolene tetrabromide crystallizes from ether in monoclinic tablets, 5 which melt at 116°. It is not a very stable compound ; after keeping for some time it melts at a lower temperature, and changes into a porcelain-like mass, which, on crystallization from ether, yields only partially the pure" tetra- bromide. i Wallach, Ann. Chem., 239, 23. ^Baeyer, Ber., 27, 447 and 448. »Wallach, Ann. Chem., 227, 283; 230, 263; 239, 23; 275, 107. 'Baeyer and Villiger, Ber., 27, 448. sffintze, Ann. Chem., 230, 263. 108 THE TERPEN ES. When it is treated with zinc dust and glacial acetic acid, it is reverted into terpinolene (Baeyer); alcoholic potash seems to react less readily (Wallach and Kerkhoff). 8. PHELLANDRENE. Phellandrene is characterized by its nitrosite, which was dis- covered by Cahours, and has, therefore, long been recognized as a constituent of many ethereal oils. The name phellandrene was introduced by Pesci, 1 who proved the presence of this terpene in the oil of water fennel (PheMandrium aquaticum). It is also a constituent of bitter fennel oil in which Cahours 2 discovered it, and which later served as the material for investigations regard- ing phellandrene nitrosite. The occurrence of phellandrene in these two oils was confirmed by Wallach, 3 who further showed that phellandrene occurs in the oil of elemi, 4 and that these three oils contain dextro-phellandrene whose nitrosite is levorotatcry. Levo-phellandrene was afterwards discovered by Wallach and Gildemeister 5 in eucalyptus oil {Eucalyptus amygdalina) ; its nitrosite rotates the plane of polarization to the right. Bertram and Walbaum 6 found levo-phellandrene in the pine needle oils from Pmus montana and Picea excelsa, while Power and Kleber 7 proved its presence in bay oil. According to Wallach and Khein- dorf, 8 dextro-phellandrene is contained in the distillation-products of the soft and hard elemi resins. The results of experiments performed in the laboratory of Schimmel & Co. indicate that phellandrene is widely distributed, and that it is contained in the following oils : — andropogon oil, angelica oil, bay oil, peppermint oil, camphor oil, curcuma oil, oils from sassafras bark and leaves, ginger oil, star anise oil, pepper oil, dill oil, wormwood oil, golden rod oil, lemon oil, olibanum oil and cinnamon oil. Phellandrene is found in the fractions boiling at about 170° of the above-mentioned oils ; a method for the preparation of pure phellandrene is not at present known. Oils containing this hydro- 'Pesci, Gazz. Chim., 16, 225. 2 Cahours, Ann. Chem., 41, 74; compare Bunge, Zeitschr. Chem., 1869, 579; Chiozza, Gerhardt's Lehrb., German edition, 8, 394. ? Wallach, Ann. Chem., 2S9, 40. i Wallach, Ann. Chem., 246, 233. 6 Wallach and Gildemeister, Ann. Chem., 246, 282 and 233. 6 Bertram and Walbaum, Arch. Pharm., 231, 290. 'Power and Kleber, Pharm. Rundschau, i89J,No. 13; compare Schimmel'» Semi-Annual Report, April, 1895, 13; see also Pharm. Review, 1896. s Wallach and Rheindorf, Ann. Chem., 271, 310. PHELLANDRENE NITROSITE. 109 carbon are fractionated in a vacuum 1 since it is partially de- composed by distillation at ordinary pressure. Properties. Phellandrene occurs in two modifications which are distinguished by opposite rotator powers, and boils at about 170°. By the distillation of the oil of water fennel, Pesci 2 obtained a fraction which contained about eighty per cent, of phellandrene, boiled at 171° to 172°, had the specific gravity 0.8558 at 10° and the specific rotatory power, \a\ D = + 17.64°. Wallach 4 found that phellandrene from an Australian euca- lyptus oil boiled at 65° (12 mm.), had the sp. gr. 0.8465 and re- fractive index, * D = 1.488, at 19°. Gildemeister and Stephan 3 found the optical rotation of phellandrene from schinus oil to be \a] D = + 60° 21'. It is one of the most unstable of the terpenes. If the fractions of the oils of fennel which contain phellanderne are saturated with hydrobromic acid, a violent reaction takes place, and when the reaction-product is poured into water, a heavy oil separates ; this oil yields dipentene by heating with sodium acetate and glacial acetic acid. If the same fractions of the fennel oils are warmed with alcoholic sulphuric acid, the phellandrene is converted into terpinene (Wallach 5 ). Although the substances which occur to- gether with phellandrene in the fennel oils influence to some ex- tent the character of the products resulting in the above-men- tioned reactions, nevertheless it is remarkable that in both cases no trace of phellandrene can be detected in the reaction-prod- ucts. . Phellandrene dibromide 1 is an oil, and is probably a mixture. It yields considerable cymene by boiling with alcoholic potash. Phellandrene nitrosite, 6 C 10 H 16 N 2 O 3 , is prepared by adding a solution of five grams of sodium nitrite in eight cc. of water to a solution of five cc. of the fraction of the ethereal oil containing phellandrene in ten cc. of petroleum ether, and then adding slowly, with constant stirring, five cc. of glacial acetic acid. The resulting crystals are filtered, washed with water and methyl alcohol, and finally purified by dissolving in chloroform and pre- cipitating with methyl alcohol. It dissolves easily in ethyl acetate, and melts at 104° to 105°. Only the perfectly pure sub- stance can be recrystallized without decomposition, the crude nitrosite suffering complete decomposition by such treatment. iWallach and Herbig, Ann. Chem., 287, 371. sPesci, Gazz. Chim., 16, 225; Ber., 19, 874, Ref. »Gildemeister and Stephan, Arch. Pharm., 235, 591. * Wallach, Ann. Chem., 287, 383. sWallach, Ann. Chem., 239, 43. «Wallach and Gildemeister, Ann. Chem., 2^6, 282. 110 THE TERPENES. Bertram and Walbaum 1 recommend the purification of this com- pound by solution in ethyl acetate and precipitation with sixty per cent, alcohol. For the preparation of large quantities of phellandrene nitrosite, compare Wallach and Herbig. 2 The nitrosite prepared from dextro-phellandrene is optically levorotatory ; Pesci 3 found its specific rotatory power, [a] D = — 183.50°. The nitrosite of levo-phellandrene is dextrorotatory. By mixing the solutions of equal quantities of dextro- and levo- phellandrene nitrosite, an optically inactive modification 4 is ob- tained, which is identical in all other properties with the two active derivatives. According to a more recent investigation by Schreiner, 5 crude phellandrene nitrosite, prepared from a levorotatory fraction of an eucalyptus oil containing phellandrene, has the rotatory power JXU = + 28.5°. When the crude nitrosite is rapidly dissolved in boiling ethyl acetate and then cooled with ice-water, a nitrosite separates which melts at 120° to 121°, has the rotation, [a] D = -f 123.5°, and forms long, well defined needles; on precipitat- ing the ethyl acetate mother-liquor with sixty per cent, alcohol, a second nitrosite is obtained, which melts at 100° to 101°, has the optical rotation, [ Wallach, Ann. Cheni., 252, 134. TERPENE FROM INDIAN HEMP. 119 According to Semmler, 1 tanacetene boils at 60° to 63° under 14 mm. pressure, has the sp. gr. 0.8508 and refractive index, n^ = 1.476, at 20°. It contains two ethylene linkages. According to Wallach, 2 thujene boils at 170° to 172°, has the sp. gr. 0.836 and refractive power, n^ = 1.47145, at 22°. In a more recent publication, Tschugaeff 3 states that thujyl alcohol, C 10 H 17 OH, may be converted into a methyl xanthate, and that when this compound is dry distilled it yields a new terpene, C 10 H 16 ; the latter boils at 151° to 152.5°, has a sp. gr. 0.8275 at 20 °/4°, and the refractive index, = 1.45042, at 20° ; the molecular refraction is 44.21, while the calculated value for a dicyclic terpene is 43.54. It does not form a crystalline nitroso- chloride, does not form an additive compound with bromine, but instantly decolorizes permanganate solution ; in the air it is rap- idly oxidized to a resin. It forms a crystalline compound with hot mercuric acetate solution. Tschugaeff regards this new terpene as belonging to the true thujone series and designates it as " thujene." The terpene above mentioned under the name thujene or tanacetene is considered as a derivative of isothujone and is therefore called " isothujene" (Tschugaeff). Bv the dry distillation of trimethyl thujylammonium hydroxide, C 10 H 17 N(CH S ) 3 • OH, Tschugaeff 4 obtained a thujene which boils at 151° to 153°, has a sp. gr. 0.8263 at 20°/4°, refractive index, nj,= 1.45022, at 20°, and a rotatory power, [a] D = — 8.23°. Since this rotatory power is much greater than that of the thujene obtained from thujyl alcohol as above described, it is perhaps pos- sible that thujone, C 10 H 16 O, gives rise to two stereoisomeric thujyl alcohols, C 10 H 17 OH, on reduction, and these yield two stereo- isomeric thujenes. A dextrorotatory thujene 4 {\_a\ D = + 21.83° in a ten cm. tube) has been obtained from the last fraction formed in the dis- tillation of methyl thujylxanthate. 11. TERPENE FROM THE RESIN OF INDIAN HEMP. A terpene, which appears to be different from those previously described, is found in the distillate, boiling from 160° to 180°, of the resin of Indian hemp. 5 It has the composition, C 10 H 16 , boils i Semmler, Ber., 25, 3345. «Wallach, Ann. Chem., 286, 97. sTschugaeff, Ber., 83, 3118. 'Tschugaeff, Ber., 84, 2276. sWood, Spivey, and Easterfield, Journ. Chem. Soc, 69, 541. 120 THE TERPENES. at 170° to 175°, and has the specific gravity 0.819 at 17° ; it is slightly levorotatory. It has a pleasant odor, and resinifies very rapidly on exposure to the air. It combines with hydrogen chlo- ride, forming an oily monohydrochloride. 12. SYNTHETICAL TERPENE. A terpene, C 10 H 16 , which may possibly prove to be the first representative of the class of ortho-terrenes, was obtained by Wailach 1 during his investigation of synthetical (ortho-l) pule- gone, C 10 H ]6 O. By reducing synthetical pulegone with sodium and alcohol, pulegol, C 10 H l7 OH, is formed. When pulegol is heated with phosphoric anhydride, and the reaction-product is distilled with steam, the above-mentioned terpene is produced. Its odor re- sembles that of limonene and of terpinolene ; it boils at 173° to 175°, has the specific gravity 0.823 and refractive index, = 1.4601, at 18°. Further investigations may show some changes in these physical constants, since the terpene has not been pre- pared in an absolutely pure condition. 13. FENCHELENE. This terpene 2 is produced as a by-product in the formation of fencholenyl alcohol, C 10 H 17 OH. It boils at 66° to 70° under 20 mm. pressure, and at 175° to 178° under 760 mm. pressure. It has the specific gravity 0.842, and the index of refraction, = 1.47439, at 20°. 14. EUTERPENE. This terpene 3 is formed when dihydroeucarveol, C 10 H 17 OH, is treated with phosphorus pentachloride, and the resulting chlo- ride, after removal of the phosphorus oxychloride, is boiled with quinoline for thirty minutes. It boils at 161° to 165°. It yields acetic, oxalic, and ^em-dimethylsuccinic acids, when it is oxidized with permanganate. Euterpene forms a dihydrobromide, which, when acted upon by bromine in the presence of iodine and then is reduced with zinc and alcoholic hydrochloric acid and finally with sodium and alcohol, yields 1.2.^-dimethyl-ethyl-benzene, boiling at 185° to 191°. 'Wallach, Ber., 29, 2957. 2Wallach, Ann. Chem., 300, 294. 3 Baeyer and Villiger, Ber., 31, 2067. SABINENE GLYCOL. 121 15. TRICYCLENE. This hydrocarbon was obtained by Wagner 1 by treating pinene dibromide, C 10 H 16 Br 2 (m. p. 169° to 170°), with zinc dust and acetic acid. It has the composition, C 10 H 16 , melts at 65° to 66°, and boils at 153°; it is indifferent towards potassium permanga- nate. It forms a solid addition-product with hydrogen chloride. 16. BORNYLENE. When pinene hydriodide is heated with forty per cent, alcoholic potash in an autoclave at 170° for four hours, a mixture of camphene and another hydrocarbon is produced. This mixture is fractionally distilled, and the fraction boiling at 152° to 160° is heated with acetic acid in a sealed tube at 55° to 60°; the camphene is thus converted into isobornyl acetate, while the other hydrocarbon remains unchanged and is separated by frac- tionation. This hydrocarbon, C 10 H, 6 , which Wagner 2 calls bornylene, melts at 97.5° to 98°, boils at 149° to 150° under 750 mm. pressure, and sublimes readily at the ordinary tempera- ture. It is oxidized at the ordinary temperature by a dilute solu- tion of potassium permanganate yielding camphoric acid. Wagner regards it as the hydrocarbon corresponding to camphor and borneol, and suggests the name bornylene to show this relation ; for camphene, which may be readily converted into isoborneol, he proposes the name isobornylene. 17. SABINENE. The fraction of oil of savin which distills below 195° consti- tutes about thirty per cent, of the crude oil, and consists mainly of terpenes. On redistillation of this fraction, an oil is obtained which boils between 162° and 170°, and consists principally of a terpene, C 10 H 16 , which Semmler 3 calls sabinene. It has a specific gravity 0.840, a refractive index, fx D = 1.466, and a molecular refraction, M= 44.9. It forms a liquid di- bromide, having the specific gravity 1.50, but yields no definite compound with nitrous acid. It is regarded as a psewdo-terpene. Sabinene glycol, C 10 H 16 (OH) 2 , results on the oxidation of sabi- nene with ice-cold, aqueous potassium permanganate; it boils at 148° to 150° under 15 mm. pressure, crystallizes from water, and 'Godlewski and G. Wagner, Chem. Centr., 1897 (L), 1055* Journ. Russ. Chem. Soc, 29, 121. »G. Wagner and Brykner, Ber., 33, 2121. «F. Semmler, Ber., 33, 1455; 34, 708. 122 THE TERPENES. melts at 54°. It has the specific gravity, 1.021, the refractive index, fi D — 1.402, and a molecular refraction, M = 47.41. Dihydrocuminyl alcohol, C 10 H 15 OH, is produced by warming the glycol with acidified water; it boils at 242°, has a sp. gr. 0.9572,/^= 1.5018, and M = 46.80. Chromic acid oxidizes it to cuminyl alcohol and cumin aldehyde. Sabinenic acid, C 10 H 16 O 3 , is formed together with sabinene gly- col ; it is an oxy-acid, crystallizes from water, melts at 57°, and forms a sparingly soluble, crystalline sodium salt. When this acid is distilled in vacuum, it loses water and hydro- gen, and yields cumic acid, C 10 H 12 O 2 (m. p. 117° to 118°). Sabinene, sabinene glycol and sabinenic acid are all dextro- rotatory. Sabinene ketone, C 9 H u O, is obtained on the oxidation of sabi- nenic acid with lead peroxide ; it boils at 213°, has a specific gravity 0.945, a refractive index, ^ = 1.4629, and a molecular refrac- tion, M = 40.26. Its semicarbazone crystallizes from alcohol, and melts at 135° to 137°. Theketone is levorotatory, \a\ D = — 18° in a ten cm. tube. In conclusion, the most important transformations of the several terpenes into each other are briefly presented in the following table : Transformations in the Terpene Series. Pinene -> Dipentene ■ [Limonene] A A Terpinel C 10 H 18 (OH) 2 A Terpineol- ,C in H„OH : Camphor Pinole Cineole = Ci 0 H 16 O C 10 H 16 O C 10 H 18 O ^-Terpinene^. AAA Terpinolene AAA HYDROCARBONS, C 10 H 1. DIHYDROCAMPHENE , C 10 H 18 . Baeyer 1 seems to have first prepared this hydrocarbon by the action of zinc dust and glacial acetic acid at a low temperature on pinene hydriodide and on bornyl iodide, C ]0 H ]7 I. Bredt and v. Rosenberg 2 obtained dihydrocamphene by the reduction of pinene hydrochloride and of bornyl chloride with sodium and alcohol. Armstrong 3 speaks of dihydrocamphene under the term camp- hydrene, and he mentions its preparation from pinene hydrochloride by the action of sodium. Semmler 4 has also recently prepared this hydrocarbon by the reduction of pinene hydrochloride, pinene dibromide, camphene hydrochloride, and camphene dibromide with sodium and alcohol. Dihydrocamphene 8 is a saturated hydrocarbon, and may be freed from impurities by treatment with fuming nitric acid. It melts at 155.3°, and boils at 159.5°. According to Semmler, it separates from alcohol in crystals belonging to the hexagonal system, melts at 155°, and boils at 160° to 162° (uncorr.). Aschan 6 describes a compound, C 10 H 18 , which is probably di- hydrocamphene, under the name camphane. He obtains it by the reduction of a nearly inactive pinene hydriodide in an acetic acid solution by means of zinc and hydriodic acid j the product, an inactive camphane (dihydrocamphene), crystallizes in six-sided plates, and melts at 153° to 154°. This saturated hydrocarbon, C 10 H 18 , is also called camphane by Forster 7 in a paper entitled, "Studies in the Camphane Series"; thus, the compound C 10 H 16 BrNO 2 , which is obtained from cam- phoroxime, is called bromonitrocamphane, and the compound, C 10 H 17 NO 2 , nitrocamphane, etc. It may be mentioned that a hydrocarbon, C 20 H 34 , termed dihy- drodicamphene, 8 is formed by the action of metallic sodium upon molten pinene hydrochloride. It is a solid, melting at 75° and boiling at 326° to 327°. 'Baeyer, Ber., 26, 826. 2 Private communication to Dr. Heusler. ^Armstrong, Journ. Chem. Soc, 69 (1896), 1398. «F. Semmler, Ber., S3, 774 and 3420. 6 Bredt and v. Rosenberg. 60. Aschan, Ber., S3, 1006. 'M. 0. Forster, Journ. Chem. Soc, 77 (1900), 251. «Etard and Meker, Compt. rend., 126, 526. 123 124 THE TEEPENES. 2. ISODIHYDROCAMPHENE, C 10 H According to Semmler, 1 when isoborneol is heated with zinc dust for thirty minutes at 220°, it is converted into a mixture of a small quantity of camphene and a much larger amount of a hydrocarbon, C 10 H 18 ; the latter compound is designated as isodi- hydrooamphene. It crystallizes from alcohol in fern-like aggre- gates, which belong to the isometric system. It melts at 85° and boils at 162° (uncorr.). While the dihydrocamphenes may be termed the parent-sub- stances of the terpenes, pinene and camphene, as well as of cam- phor, the following hydrocarbons, carvomenthene and menthene, are to be regarded as tetrahydrocymenes. By the separation of the elements of water from carvomenthol (tetrahydrocarveol), C 10 H 19 OH, it may be converted into a hydro- carbon, C 10 H 18 , which differs from menthene, C 10 H 18 , obtained from menthol in an analogous manner. Therefore, the constitu- tion of carvomenthene and of menthene can not be expressed by formula I., according to which both compounds must be identical, but should rather be regarded as corresponding to formulas II. 3. CARVOMENTHENE, C 10 H and III. (Baeyer). H 3 C CH 3 Carvomenthol ( tetrahydrocarveol ) . Menthol. H 3 C CH 3 Carvomenthene. «F. Semmler, Ber., 33, 774. H 3 C CH 3 Menthene. CARVOMENTHENE HYDROBROMIDE. 125 Baeyer 1 prepared carvomenthene by treating tetrahydrocarveol (carvomenthol) with hydrobromic acid, and distilling the result- ant bromide with quinoline, while Wallach 2 obtained it by heat- ing tetrahydrocarveol with acid potassium sulphate for one hour at 200°. When purified in the usual manner, it boils at 175° to 176° (corr.). According to more recent investigations by Kondakoff and Lutschinin, 3 carvomenthene is formed by heating carvomenthyl chloride or bromide with alcoholic potash ; on fractional distilla- tion, the resultant hydrocarbon may be separated into two por- tions, about ninety per cent, of the whole boiling at 172° to 174.5°, and the remainder at 174.5° to 178°. Properties. — The fraction of carvomenthene of the lower boil- ing point has the specific gravity 0.8230 at 16.3°/4°, a refractive index, n^ = 1.45979, a molecular refraction, M = 45. 68, and a specific rotation, [= + 1.015° to + 20.64°, and melt from 106° to 119°. No satisfactory method has yet been found by means of which the different modifications of the nitrosochloride can be separated from the mixture. It should further be noted that Urban and Kremers 4 obtained an inactive nitrosochloride, melting at 128°, and that Baeyer 5 has mentioned a menthene nitrosochloride, melting at 146°. Tschu- gaeff 6 has also prepared a nitrosochloride, melting at 127° and having [«] jD = 242.5°. Menthene nitrosate, C 10 H lg -N 2 O 4 , melts at 98°, and is optically inactive (Urban and Kremers). Menthene nitrolbenzylamine, NH • CH 2 • C,H 6 is prepared in the usual manner from the nitrosochloride or nitro- sate. It is optically inactive, and melts at 105.5° to 107°. Ac- iBrühl, Ber., 25, 151. «Wagner, Ber., 27, 1636; Kondakoff, Ber., 28, 1618; Journ. pr. Chem., 60 [II.], 257. Sicker and Kremers, Amer. Chem. Journ., 1%, 292; Urban and Kremers, Amer. Chem. Journ., 16, 395; Richtmann and Kremers, Amer. Chem. Journ., 18, 762. «Urban and Kremers, Amer. Chem. Journ., 16, 395. sßaeyer, Ber., 26, 2561. <>Tschugaeff, Ber., 32, 3332. NITROSOMENTHENE. 129 cording to Richtmann and Kremers, the nitrosochlorides having specific rotatory powers differing by 30° all yield optically in- active benzylamine bases, melting at 105.5° to 106.5°. Nitrosomenthene, 1 C 10 H 16 NOH, is obtained by boiling menthene nitrosochloride with alcoholic potash. It also results when the nitrosochloride is heated in a tube at about 115°; in this case hydrochloric acid is given off, and the resultant nitrosomenthene sublimes slowly, and condenses in the cooler parts of the tube. It is purified by distilling in a current of steam, and melts at 65° to 67°. Nitrosomenthene prepared from dextrorotatory menthene nitrosochloride is levorotatory, and the inactive modification is formed from the inactive nitrosochloride. By reduction of nitrosomenthene with zinc dust and acetic acid, Urban and Kremers obtained inactive menthone and a menthyl- amine ; this base forms a crystalline nitrate, which, on treating with nitrous acid, yields an alcohol, C lt) H 17 OH, boiling at 210° to 215°. Nitrosomenthene is fairly stable towards sulphuric and acetic acids. When it is warmed with hydrochloric acid, a ketone, menthenone, C 10 H lfi O, is formed ; it boils at 206° to 208°, and is reconverted into nitrosomenthene by heating with hydroxylamine. The oxidation of menthene with potassium permanganate has been studied by Wagner 2 and Tolloczko. 3 According to Wagner, the following products are obtained by oxidizing menthene at about 0° with a one per cent, solution of permanganate. 1. Menthene glycol, C 10 H 18 (OH) 2 . — This glycol is an oily, viscid liquid, boiling at 129.5° to 131.5° under 13 mm. pressure; it partially solidifies after a time and crystallizes from ether, melt- ing at 76.5° to 77° ; the permanent liquid portions yield a diac- etate, a monoacetate, and a terpene, C 10 H 16 , when treated with acetic anhydride. 2. Ketone alcohol, C 10 H 17 O(OH). — This compound is a liquid, having the specific gravity 0.9881 at 0°, and boils at 104.5° to 105.5° at 13.5 mm. pressure. It yields a phenylur ethane, C 17 H 23 0 3 N, melting at 157°, and an oxime, C 10 H 19 O 2 N, which crystallizes from ether in microscopic tablets, melting at 132° to 133°. 3. Acetic acid, methyl adipic acid, and f-isobutyryl-/2-methyl valeric acid (oxymenthylic acid). — These acids are also formed in the oxidation of menthone with potassium permanganate. ■Urban and Kremers, and Richtmann and Kremers. «Wagner, Ber., 27, 1636. s Tolloczko, Ber., 28, 926, Ref. 9 130 THE TERPENES. Meta-menthene (1 : 3-m.etliyl-isopropyl-cyclohexene), C ]0 H 18 , is a hydrocarbon, which has been prepared by Knoevenagel 1 by heating cis-syrn metrical menthol with phosphoric anhydride at 110° to 130°. It is a liquid, having an odor resembling that of turpentine, and is an unsaturated compound ; it boils at 169° to 170° under a pressure of 746 mm., has a specific gravity 0.8197 at 16°/4°, the index of refraction, n^ = 1.45609, and the molecular refraction, R = 45.67. According to Kondakoff, 2 a hydrocarbon, C 10 H 18 , is obtained from the oil of buchu leaves; it boils at 174° to 176° at 762 mm. pressure, at 65° to 67° under 14 mm., has a specific gravity 0.8648 at 18.5°, and a specific rotatory power, x^ = + 60.20°. Its odor resembles that of peppermint. Cyclo-linalolene, C 10 H 18 , will be described under linalolene. HYDROCARBONS, C 10 H 20 . Many members of the terpene series are converted into hydro- carbons, C 10 H 20 , by heating with liydriodic acid and red phos- phorus at about 200°. A sharp characterization and identification of these compounds have been impossible, since they are chemic- ally very indifferent substances, and their transformations into crystalline derivatives have not yet succeeded. It is probable, therefore, that some of the following hydrocarbons, which are chiefly named after the products from which they are derived, are identical. It is to be noted that, according to Baeyer's nomencla- ture, hexahydrocymene is called terpane, while Wagner suggests the name menthane. Tetrahydropinene, C 10 H 20 , is described by Wallach and Berken- heim 3 as a hydrocarbon produced by the hydration of pinene hydrochloride; it boils at 162°, has the specific gravity 0.795, and the refractive index, n^ = 1.43701°, at 20°. Bromine acts on it, forming substitution products ; nitric acid and a mixture of nitric and sulphuric acids do not attack this hydrocarbon in the cold, but warm nitric acid dissolves and oxidizes it. A warm so- lution of permanganate oxidizes it very slowly, forming valeric acid. The hydrocarbon obtained by Orlow 4 by the direct hydra- tion of oil of turpentine should in all probability be regarded as tetrahydropinene. 'Knoevenagel and Wiedermann, Ann. Chem., 297, 169. sKondakoff, Journ. pr. Chem., 54, 433. «Wallach and Berkenheim, Ann. Chem., 268, 225. *Orlow, Ber., 16, 799. META-MENTHANE. 131 Tetrahydrofenchene, C 10 H 20 , was obtained by Wallach 1 in the reduction of fenchyl alcohol, fenchone and fenchylamine with hydriodic acid and phosphorus. It boils at 160° to 165°, and has the specific gravity 0.7945 and index of refraction, n^= 1.4370, at 22°. In its chemical behavior it resembles tetrahydropinene ; bromine acts upon it forming a solid substitution-product, although the yield is extremely small. This bromide crystallizes from ethyl acetate in the form of needles, which melt above 200°, but they have not been analyzed. Starodubsky obtained a hydrocarbon, C 10 H 20 , in a similar manner from camphor; it boils at 167° to 169°, and has the specific gravity of 0.8114 at 15°. A hydrocarbon, C 10 H 20 , is obtained by the reduction of terpine hydrate; it boils at 168° to 170°, and has the specific gravity 0.797 at 15° (Schtschukarew 2 ). The hydrocarbon, C 10 H 20 , prepared by Wagner 3 by the action of concentrated sulphuric acid on menthol, is to be regarded as hexahydrocymene, and, according to Wagner, is called menthane. The same compound is also formed by the reduction of menthol with hydriodic acid and phosphorus, and is designated by Berken - heim 4 as menthonaphthene. According to Wagner, it boils at 1 68° to 169°, and has the sp. gr. 0.8066 at 0° ; according to Berken- heim, it boils at 169° to 170.5°, and has the specific gravity 0.8067 at 0° and 0.796 at 15°. Jünger and Klages 5 state that this hexahydrocymene is best prepared by reducing menthyl chloride with sodium and alcohol, and shaking the reaction-product with concentrated sulphuric acid. Meta-menthane 6 (1 : 3-methyl-isopropylcyclohexane), C 10 H 20 , is prepared by the reduction of symmetrical menthyl iodide. It boils at 167° to 168° under a pressure of 756 mm., has a specific gravity 0.8033 at 14°/4°, refractive index, n^ = 1.44204, and molecular refraction, R = 46.02. It is not acted upon by con- centrated sulphuric and nitric acids, bromine, and solutions of potassium permanganate. A hexahydrocymene, C 10 H 20 , isolated by Renard 7 from the essence of resin by means of sulphuric acid, boils at 171° to 173°, and has the specific gravity 0.8116 at 17°. iWallach, Ann. Chem., 284, 326. «Schtschukarew, Ber., 23, 433c. 3 Wagner, Ber., 27, 1638. 'Berkenheim, Ber., 25, 686. 5 Junger and Klages, Ber., 29, 317. 6 Knoevenagel and Wiedermann, Ann. Chem., 297, 169. 'Renard, Ann. Chim. Phys. [6], 1, 223. 132 THE TERPENES. Berken heim 1 has published the results of experiments on the relations of the naphthenes, C 10 H 20 , occurring in Russian petroleum, to the hydrocarbons under consideration, and to the terpenes. Diethyl hexamethylene, C 10 H 20 , was synthetically prepared by Zelinsky and Rudewitsch. 2 According to these chemists, diethyl- keto-hexamethylene, C 10 H 18 O, is obtained by the distillation of diethyl pimelic acid over calcium hydroxide; it boils at 205° to 207°. This ketone is converted by reduction into the alcohol, C 10 H 19 OH, which boils at 209° to 211°, and partially solidifies, the crystalline portion melting at 77° to 78°. This alcohol is converted into the iodide, C 10 H 19 I, by treatment with hydriodic acid, and when the iodide is reduced with zinc and hydrochloric acid in alcoholic solution it yields diethyl hexamethylene. The following formulas express these reactions : H CO H W H 5 C-C J (j) C 2 H 6 V CH ' CH 2 H 2 < Diethyl-keto-hexamethy- lene. H H 5 CrH H 2 < MF 1 C 2 H 5 ^^CH 2 CH 2 Iodide, C 10 H 19 I. CH 2 Alcohol, C 10 H 19 OH. H CH, H H K C, C C 2 H 6 H 2 C CH« CH 2 Diethyl hexamethylene. Diethyl hexamethylene is a colorless liquid with a petroleum- like odor. It boils at 169° to 171°, has the specific gravity, d 22°/4° = 0.7957, and the refractive index, n D = 1.4388, at 20°. It is a saturated hydrocarbon, and is immediately colored by bro- mine vapor. 1 Berkenheim, Ber., 25, 686. 2 Zelinsky and Rudewitsch, Ber., 28, 1341. OXIDIZED COMPOUNDS RELATED TO THE TERPENES, 1. SUBSTANCES WHICH CAN NOT BE REGARDED AS DERIVATIVES OF THE HYDROCYMENES. (ANALOGUES OF PINENE, CAMPHENE AND FENCHENE.) 1. CAMPHOR, C 10 H 16 O. Dextrorotatory camphor (Japan camphor) is found in the camphor tree (Laurus camphora), while levorotatory camphor occurs in the oil of Matricaria parthenium, and has, therefore, been designated as Matricaria camphor. Camphor may be pre- pared artificially by oxidizing borneol and isoborneol with nitric acid. Of especial interest is a partial synthesis of camphor which Bredt and v. Rosenberg 1 have accomplished. They obtained cam- phor by the dry distillation of the calcium salt of homocamphoric acid, prepared from camphonitrile ; 2 accepting Bredt's formula of camphor (see page 25), this reaction may be expressed by the equation : )H, CH CH— COO^ H,C— C— CH 3 Ca = CaC0 3 + CH 2 COO CH, This synthesis of camphor 3 is quite analogous to the syntheses of many keto-pentamethylenes, which have been prepared by J. Wislicenus and his students. iBredt and v. Rosenberg, Ann. Chem., 289, 1. 2Haller, Theses presentees ä la faculty des sciences de Paris; compare Claisen, Ann. Chem., 281, 349. 3 A. Haller, Bull. Soc. Chim., 15, 1896 (III.), 324. 133 134 THE TERPENES. Camphor forms a colorless, transparent, tough mass, which crystallizes from alcohol; it is very volatile, sublimes easily, melts at 175° and boils at 204°. Its specific rotatory power is ±44.22°. Optically inactive camphor is obtained by mixing together the solutions of equal weights of the active modifications, or by oxi- dizing inactive borneol ; it melts at 178.6°. Camphor is resolved into para-cymene and water when it is treated with phosphorus pentoxide ; it is converted into car- vacrol by heating with iodine. According to Bredt, 1 both of these changes involve the formation of carvenone, CLH,X), as an ^ intermediate product. The transformation of camphor into carvenone also takes place under the influence of con- centrated sulphuric acid at 105° to 110° ; the carvenone is either the direct product, or, more probably, results from dihy- drocarvone, which is readily converted into carvenone by the in- fluence of acids. " Camphren " 2 is formed by heating 200 grams of camphor with 800 grams of concentrated sulphuric acid at 105° to 110°. A mixture of borneol with about twenty per cent, of isoborneol is formed by reducing camphor in an alcoholic solution with sodium. Nitric acid oxidizes camphor into a product which con- sists chiefly of camphoric acid (m. p. 187°) and camphoronic acid (m. p. 139°) ; Bredt formulates this reaction as follows : CH, -CH- IT •C — c— c CH, CH, CH, Camphor. "CH 2 -co CH, -CH H»C- CH, -COOH COOH COOH CH 3 %*- I H 3 C— C— CH 3 COOH CH, C COOH CH, Camphoric acid. CH 3 Camphoronic acid. The discussion of camphor and its derivatives must necessarily be limited owing to the reasons mentioned in the introduction. Only those compounds will be briefly considered which are very nearly related to other members of the terpene group, and which are to be regarded as the parent-substances of certain terpene amido- compounds derived from camphor, or which may be converted by simple reactions into camphene, a terpene closely allied to cam- 1 Bredt, Rochussen, and Monheim, Ann. Chem., 814, 369. 2 Armstrong and Kipping, Journ. Chem. Soc, 63, 77 ; compare Bredt, Ann. Chem., SU, 369. CAMPHOROXIME ANHYDRIDE. 135 phor. The most important of these derivatives are camphoroxime, borneol, isoborneol, and substances obtained from them. Camphoroxime, 1 C 10 H 16 • NOH, was discovered by Nägeli. 2 In order to prepare it, dissolve twenty parts of camphor in two and one-half times its quantity of ninety per cent, alcohol, add twelve parts of hydroxylamine hydrochloride and a little more than the calculated amount of sodium bicarbonate, and warm the mixture for some time. The reaction is complete when the product wholly dissolves in dilute sulphuric acid. It crystal- lizes from petroleum ether in brilliant, hard, monoclinic 3 prisms, which, like those of the active tartaric acids, are hemimorphic (Beckmann 4 ). Camphoroxime melts at 118° to 119°, boils with slight decom- position at 249° to 250°, and smells like camphor. The presence of an oximid group is proved by the formation of a sodium salt, an ethyl ester, and a compound with phenylcyanate, 5 which melts at 94°. Leucjcart and Bach 6 obtained bornylamine, C 10 H 17 NH 2 , by re- duction of camphoroxime with sodium and alcohol ; they also prepared the same base by the action of ammonium formate on camphor. The action of nitrous acid on camphoroxime has been investi- gated by Angeli and Tiemann. 7 Camphordioxime, see Angelico, Atti. Real. Accad. Lincei, 1900 (V.), 2 (II.), 47. Camphoroxime anhydride (a-campholenonitrile), C 10 H 15 N, was first prepared by Nägeli 8 by the action of acetyl chloride on cam- phoroxime; it may also be obtained by the action of other dehy- drating agents 9 on camphoroxime, most readily by boiling with dilute sulphuric acid. 'Forster, Journ. Chem. Soc, 71, 191 and 1030; 75, 1141; 77, 251. z Nägeli, Ber., 16, 497 ; see Konowaloff, Journ. Russ. Phys. Chem. Soc, 33 (1901), 45; Auwers, Ber., 22, 605. sMuthmann, Ann. Chem., 250, 354. ^Beckmann, Ann. Chem., 250, 354. sGoldschmidt, Ber., 22, 3104. eLeuckart and Bach, Ber., 20, 104; see Konowaloff, Journ. Russ. Phys. Chem. Soc, 33, 45; Forster, Journ. Chem. Soc, 73, 386. t Angeli and Rimini, Ber., 28, 1077; Angeli, Ber., 28, 1127; Tiemann, Ber., 28, 1079; Angeli and Rimini, Gazz. Chim., 25 [1], 406; Ber., 28, 618, Ref. Tiemann, Ber., 29, 2807; Angeli, Gazz. Chim., 26 (IL), 29, 34, 45, 228, 502 and 517; 28 (I.), 11; Mahla and Tiemann, Ber., 33, 1929. »Nägeli, Ber., 16, 497. fGoldschmidt and Ziirrer, Ber., 17, 2069 and 2717; Goldschmidt and Koreff, Ber., 18, 1632; Leuckart, Ber., 20, 104; Goldschmidt, Ber., 20, 483. 136 THE TERPENES. It boils at 226° to 227°, and at 20° has the specific gravity 0.910 and the coefficient of refraction 1.46648, corresponding to the molecular refraction 45.39 (Wallach Its specific rotatory power in a one decimeter tube is [aj^ = -f 7.5 (Tiemann 2 ). It is an unsaturated compound and combines directly with halogen acids, forming oily addition-products (Wallach l ). By reduction with zinc and sulphuric acid, 3 or better with sodium and alcohol, 4 «-campholenonitrile yields a-camphylamine, C 10 H 17 NH 2 . When hydrogen chloride is passed into an alcoholic solution of the nitrile, 5 a-campholenie acid is produced, together with some isoamidocamphor, C 10 H, 5 O • NH 2 . a-Campholenamidoxime,C ]0 H 15 (NOH) . NH 2 , is produced by heat- ing a-campholenonitrile with aqueous hydroxylamine under pres- sure ; it crystallizes in white needles, and melts at 102°. Isocamphoroxime (a-campholenamide), C 9 H 15 CONH 2 , is formed, together with a-campholenic acid, by heating camphoroxime anhy- dride with alcoholic potash ; it crystallizes in leaflets, melting at 125° (Nägeli 6 ). It has the specific rotatory power, [«] 2) = — 4.06°. Warm, dilute sulphuric acid converts it into the sul- phate of isoamidocamphor, and, under certain conditions, into dihydrocampholenolactone, C 10 H 16 O 2 . It is quite readily changed into a-campholenic acid by boiling with alcoholic potash. a-Campholenic acid, C 9 H 15 . COOH (Goldschmidt and Ziirrer, 7 and Tiemann). This acid is identical with the " oxycamphor " obtained by Kachler and Spitzer; 8 it boils at 256°, has the specific gravity 0.992 at 19°, and the refractive index, n D = 1.47125, from which the molecular refraction equals 47.36. Its specific rotatory power in a one decimeter tube is [«1^= + 9° 37'. a-Dioxydihydrocampholenic acid, 9 C 9 H 17 0 2 . COOH, was first pre- pared by Wallach. It is formed by the oxidation of an ice-cold solution of sodium «-campholenate with a two per cent, solution of potassium permanganate. 10 It melts at 144°, and has \a\ D = + 58.03°. 'Wallach, Ann. Chem., 269, 330. 2 Tiemann, Ber., 29, 3006. 3 Goldschmidt and Koreff, Eer., 18, 1632. 'Goldschmidt, Ber., 18, 3297; Goldschmidt and Schulhoff, Ber., 19, 708. 5F. Tiemann, Ber., 29, 3006; 30, 242, 321 and 404. ^Nägeli, Ber., 17, 805; Tiemann, Ber., 29, 3006. 'Goldschmidt and Ziirrer, Ber., 17, 2069 and 2717. sKachler and Spitzer, Ber., 17, 2400; Monatsch. für Chem., 3, 216; If, 643. 9 Tiemann, Ber., 29, 3006; Wallach, Ann. Chem., 269, 327 and 343. "•Compare with Bouveault, Bull. Soc. Chim., 19, 1898 (III.), 565. CAMPHOR. 137 In the following is presented a very brief outline of a discussion which was carried on between Leuckart and Goldschmidt regard- ing the structure of the compounds described above (these com- pounds were not at that time designated as alpha-derivatives). The formulas of these substances are : According to Leuckart, According to Goldschmidt, Ber., W, 104. Ber., to, 483. /CH 2 /CH 2 c a H "\i 0 Ca 7 hor c ^Ho CH Y / CH 2 C8Hw < CH Camphylamine C « H "\ C h 2 . N h 2 I I y CH.NH 2 /CH, C 8 H U /^ Isocamphoroxime. C 8 H »\ C0NHi ,CHOH J /CH 2 C « H -\i 0 Cam P h ° le j add C8Hl3 \cOOH Campholene C 8 H U =CH, The most important fact which Goldschmidt and Zürrer ad- duce to support their view that camphoroxime anhydride is to be regarded as a nitrile of a monobasic acid, is their observation that a hydrocarbon, C 9 H 16 , campholene (b. p. 130° to 140°), is ob- tained by the dry distillation of the calcium salt of campholenic acid; further, an amidine 1 (m. p. 114° to 115°), is formed by iGoldschmidt and Koreff, Ber., 18, 1633. 138 THE TERPENES. heating the anhydride with toluidine hydrochloride according to Bernthsen's method. It should also be mentioned that Bamberger 1 has accepted Goldschmidt' s views, but has advanced the opinion that campho- lenonitrile is a cyanide having an open chain of carbon atoms, and has the formula : CH, Camphoroxime. Campholenonitrile Wallach's experiments, however, have proved that Bamberger's assumption is not well founded, hence a brief consideration of these experiments is given in the following. According to Wallach, 2 campholenic acid is unsaturated ; when bromine is added to its alcoholic or acetic acid solution, it forms a product which eventually becomes crystalline, and is insoluble in alkalis. Potassium permanganate, which is decolorized by sodium campholenate even in the cold, converts campholenic acid into a-dioxydihydrocampholenic acid, C 10 H 18 O 4 ; it separates from hot water in splendid crystals, melts at 144° to 145°, and yields a silver salt, C 10 H 17 O 4 Ag, and is, therefore, a monobasic acid. A saturated hydrocarbon is produced when campholenic acid is heated with concentrated hydriodic acid and red phosphorus ; it boils at 135° to 145°, and probably contains as chief con- stituent, dihydrocampholene, C 9 H 18 . These experiments show that campholenic acid, and likewise campholenonitrile, contain a cyclic structure of the carbon atoms, and one double linkage. That campholenic acid is unsaturated and has a cyclic arrange- ment of its carbon atoms, has also been proved by W. Thiel. 3 In consideration of these facts, and by employing the formula of camphor proposed by himself, Bredt 4 explains the constitution of »Bamberger, Ber., 21, 1125. 2 Wallach, Ann. Chem., 269, 327 and 343. 3 Thiel, Ber., 26, 922; compare also under pinene. *Bredt, Ber., 26, 3054. DIHYDROCAMPHOLENIMIDE. 139 campholenonitrile and of campholenic acid by the following for- mulas, which he regards as the most probable : CH, M- CH, CEL CH, CNOH -CH- CH, CH, ä C— C— CH S -c CO CH, H s O-C-C IH 0 CH 3 Camphoroxime. H CH 2 CN CH, y CH, NH Intermediary product. H CH, COOH CH 3 Campholenonitrile. H 3 C— 0— CH 3 DH==C — CH 3 Campholenic acid. According to researches of Behal, 1 and of Tiemann, 2 a second group of isomeric compounds is derived from camphoroxime; Tiemann designates these as beta-compounds. ^-Campholenonitrile, 2 C 9 H 15 CN, is obtained when camphoroxime is boiled for some time with dilute hydriodic acid. It boils^ at 225° and is optically inactive ; when reduced in alcoholic solution with sodium, it gives rise to ß-camphylamine, C 10 H 17 NH 2 . /3-Campholenamide, 2 C 9 H 15 CONH 2 , is prepared by the saponifi- cation of the /3-nitrile. It melts at 86°, and is optically inactive. /3-Campholenic acid, 2 C 9 H lf COOH, is formed by the hydrolysis of /9-campholenamide. It melts at 52°, and boils at 245°. /3-Dioxydihydrocampholenic acid, 3 C 9 H 17 0 2 • COOH, is formed by the oxidation of /3-campholenic acid with potassium permanganate. It crystallizes from chloroform or water in needles, and melts at 146°. Isocamphorone, 3 C 9 H u O, boiling at 217°, and campholonic add, 3 C 10 H 16 O 3 , a liquid ketonic acid, isomeric with the pinonic acids, are also products of the oxidation of /3-campholenic acid. Isoamidocamphor, 4 C l0 H 15 O • NH 2 , is prepared by treating cam- phoroxime with twice its weight of hydriodic acid, sp. gr. 1.96. It crystallizes in prisms, melts at 39°, and boils at 254°. Dihydrocampholenimide, 4 C 10 H 16 O • NH, is obtained by distill- ing isoamidocamphor under atmospheric pressure in such a iB6hal, Compt. rend., 119, 799; 120, 858 and 1167; 121, 213. ^Tiemann, Ber., 28, 1082; 30, 242; see Blaise and Blanc, Compt. rend., 129 (1899), 106; 131 (1900), 803. JTiemann, Ber., 30, 242. •«Tiemann, Ber., 30, 321 and 404; see Mahla and Tiemann, Ber., 33, 1929; Tiemann, Ber., 33, 2953 and 2960. 140 THE TERPENES. manner that the substance becomes slightly superheated. It crystallizes in white needles, melts at 108°, and boils at 266°. Dihydrocampholenolactone, 1 C 10 H 16 O 2 , is produced when cam- phoroxime is decomposed with moderately concentrated sulphuric acid, the liquid diluted with water, and then boiled for some time. Tiemann explains this change by assuming that a-campholenoni- trile is the first product, and that this compound passes at once into the /^-modification, which, in turn, is hydrolyzed to /9-campho- lenamide ; this is changed into isoamidocamphor, which loses am- monia forming dihydrocampholenolactone. It melts at 30°, boils at 256°, has the specific gravity 1.0303, the refractive index, n^ 1.46801, and the molecular refraction, M= 45.79. It is optically inactive. Campholene, 2 C 8 H 16 , is formed by boiling a- and /9-campholenic acids so that the material becomes slightly superheated. It boils at 133° to 135°, has a specific gravity 0.8034 at 20°, refractive index, n^, = 1.44406, at 20°, and molecular refraction, if = 41.00. As a result of his investigations 3 on camphor and the campho- lene group, as well as from the researches of Tiemann and Mahla 4 on the oxidation products of camphoric acid, Tiemann concludes that the formula of camphor, which he has proposed and made to conform with Bredt's acceptance of a hexamethylene ring formed by the combination of two pen tam ethylene rings, is proved. Whether this opinion is correct, the future investigations must determine. At the present time, the question regarding the con- stitution of camphor seems to be an open one, notwithstanding the great amount of work which has been carried on regarding it. Camphor semicarbazone, C 10 H 16 = N • NH • CO NH„ melts at 236° to 238° (Tiemann 5 ). Oxymethylene camphor, .C = CHOH I CO is obtained by the action of sodium and amyl formate on a solu- tion of camphor in ether (Glaisen). It is a white, crystalline sub- stance, melts at 80° to 81°, and when dissolved in water or 'Tiemann, Ber., 30, 321 and 404; Bouveault, Bull. Soc. Chim., 19, 1898 (III.), 565. 2 Tiemann, Ber., 30, 594. 'Tiemann, Ber., 28, 1079, 2166; 29, 119, 3006; 30, 242, 321, 404, 594; 33, 2935; compare Bredt, Ann. Chem., 289, 15; Forster, Journ. Chem. Soc., 75, 1141; 79, 108; Walker, Journ. Chem. Soc, 63, 495; 67, 347; 77, 394: Blanc Bull. Soc. Chim... 1900 [III.], 28, 695. 'Mahla and Tiemann, Ber., 28, 2151; 29, 2807; 33, 1929; compare Bal- biano, Ber., 80, 289, 1901; Real. Accad. dei Lincei, 8 (1899), 422; Gazz. Chim., 29 (II.), 490. 5 Tiemann, Ber., 28, 2191; see also Rimini, Gazz. Chim., 80 (I.), 600. BOENEOL. 141 aqueous alcohol, it turns blue litmus paper red. Its alcoholic solution is colored reddish-violet by the addition of ferric chloride ; a further addition of this reagent produces a blue, and finally a dark green color. It has been carefully investigated by Bishop, Claisen, and Sinclair. 1 Campholic acid, C 9 H 17 COOH, is the parent-substance of cam- pholamine and camphol alcohol ; it is prepared by the method given by Errera. 2 To a -boiling solution of 500 grams of cam- phor in 250 grams of benzene, thirty-eight grams of sodium are gradually added ; the benzene is then distilled off, and the residual mass is heated at 280° for twenty-four hours. The reaction-product is treated with water, shaken with ether, and the aqueous solution acidified with hydrochloric acid ; the resultant campholic acid is distilled with steam. A yield of twenty per cent, may be obtained by careful treatment of the mother-liquor. Campholamide, C 9 H 17 CONH 2 , is produced by heating ammonium campholate at 230°, or by treating the acid chloride with am- monia. It crystallizes from water or petroleum ether in needles, and melts at 79° to 80°. Campholonitrile, C 9 H 17 CN, is formed in large quantities as a by- product in the preparation of campholamide, and is separated from the latter by distillation with steam. It melts at 72° to 73°, boils at 217° to 219°, and resembles camphor in odor and appearance. It yields campholamine on reduction with sodium and alcohol (Errera 3 ). For condensation-products of camphor with aldehydes, see in- vestigations of Haller. 4 Camphor pinacone, C 20 H 34 O ? , is formed, together with borneol, by the reduction of camphor in indifferent solvents ; it is odor- less, tasteless, very slightly volatile with steam, crystallizes in rhombic pyramids, and melts at 157° to 158°. Dextro-camphor yields a levorotatory pinacone, while levo-camphor gives rise to a dextrorotatory derivative. Various derivatives of this pinacone have been prepared (Beckmann 5 ). 2. BORNEOL, C 10 H 17 OH. Borneol occurs in nature in an optically dextrorotatory and levorotatory, as well as in an inactive, modification ; it is found i Bishop, Claisen and Sinclair, Ann. Chem., 281, 314. 2 Errera, Gazz. Chim., 22 [1], 205; Ber., 25, 466, Ref. »Errera, Gazz. Chim., 22 [2], 109; Ber., 26, 21, Ref. * A. Haller, Compt. rend., 128, 1270; 130, 688; 138, 79; see also Hel- bronner, Compt. rend., 133, 43. 5E. Beckmann, Ber., 22, 92; 27, 2348; Ann. Chem., 292, 1; Journ. pr. Chem. [IL], 55, 31. 142 THE TERPENES. free, and also in the form of esters. The most important occur- rence of dextro-borneol is in the pith cavities of Dryobalanops eamphora ("Borneo-camphor"); it is also found in oil of rose- mary and oil of spike. The so-called " Ngai-camphor " from Blumea balsamifera consists of levorotatory borneol. Valerian oil _ contains levo-borneol (" Valerian-camphor "), and some in- active borneol ; the latter modification has also been found in oil of sage. In the form of esters of the lower fatty acids, especially acetic acid, levo-borneol is a constituent of many fir and pine oils ; thus, Bertram and Walbaum 1 have detected it in pine needle oil from Abies alba, Canadian pine oil, hemlock oil, pine needle oils from Picea excelsa and Pinus montana, while Hirschsohn 2 has found it in the oil of Abies siberica L. In the same manner bor- neol occurs in oil from Satureja thymbra L., oil of golden rod, sage oil, and oil of thyme. According to Kremers, 3 the oil of Picea nigra is especially rich in levo-bornyl acetate. Borneol (" levo-camphenol" 4 ) is produced by heating French oil of turpentine with benzoic acid at 150° for fifty hours. For the preparation of borneol from camphor the following method is employed ; it is Wallach's 5 modification of the old method proposed by Jackson and Menke, 6 and Immendorf. 7 t Fifty grams of camphor are dissolved in 500 cc. of ninety- six per cent, alcohol in a spacious flask connected with a wide reflux condenser, through which sixty grams of sodium are gradually added. The operation should require about one hour for its completion, and the spontaneous rise of temperature must uot be prevented by cooling; it is in fact advisable when the reaction eventually becomes moderate, to accelerate the solution of the last portions of sodium by the careful addition of about fifty cc. of water. When the sodium is dissolved the product is poured into three or four liters of water, the separated borneol is filtered, pressed on a porous plate and crystallized from petroleum ether. According to Bertram and Walbaum, 8 the borneol so prepared is not pure, but contains about twenty per cent, of isoborneol. Bertram and Walbaum, Arch. Pharm., 231, 290. 2 Hirschsohn, Pharm. Zeitsch. f. Russland, 1892, No. 38. 3 Kremers, Pharm. Rundschau, 18, 135. *Bouchardat and Lafont, Compt. rend., US, 551; 125, 111. 5 Wallach, Ann. Chem., 280, 225. 6 Jackson and Menke, Ber., 15, 16 and 2730. Emmendorf, Ber., 17, 1036. "Bertram and Walbaum, Journ. pr. Chem., N. F., 49, 12; see Beckmann, Journ. pr. Chem., 55, 1897 (II.), 31. METHYL. BORNYL ETHER. 143 These chemists obtained chemically pure borneol by saponification of crystalline bornyl acetate. Beckmann 1 effected the reduction of camphor into borneol by repeated, alternate treatment of a solution of camphor in ether with sodium and water. Properties. — Borneol, prepared by "Wallach's method, melts at 206° to 207°; pure borneol derived from its acetate, or from " borneo-camphor," or from oil of valerian, melts at 203° to 204°. It boils at 212°, and crystallizes in hexagonal plates (Traube 2 ). Its solution in petroleum ether unites with bromine, forming a yellowish-red, unstable additive compound, which soon decom- poses on standing in the air (Wallach 3 ). Two molecules of borneol combine with one molecule of hydro- bromic or hydriodic acid, yielding compounds which are easily decomposed. If borneol be oxidized with nitric acid (sp. gr. 1.4), camphor results. Camphene is formed when borneol is heated with acid potassium sulphate. Several esters of borneol have been synthetically prepared by Bertram and Walbaum ; 4 the properties of these compounds are given in the following table : Boiling Point, (10 mm.). Optical Rotation in 100 mm. Tube. Sp. Gr. at 15°. Refraction n fl at 15°. Percentage of Ester Determined by Titration. Formate. Acetate. Propionate. Butyrate. Valerate. 90° 80° 109° to 110° 120° to 121° 128° to 130° +31° —38° 20' +24° +22° + 20° 1.013 0.991 0.979 0.966 0.956 1.47078 1.46635 1.46435 1.46380 1.46280 97.89 100.60 97.07 99.20 98.56 Bornyl acetate, C 10 H 17 OCOCH 3 , is of especial importance, since it is a constituent of the oil of pine needles, and because it is a solid and possesses great power of crystallization. It melts at 29° and forms orthorhombic, hemihedral crystals (Traube). Methyl bornyl ether, C 10 H 17 OCH 3 , was prepared by Baubigny 5 and by Brühl. 6 It is a liquid, boiling at 194° to 195°. i Beckmann, German patent, No. 42458; Ber., 21, 321, Ref.; 22, 912. »Traube, Journ. pr. Chem., N. F., 49, 3. sWallach, Ann. Chem., 230, 226. ^Bertram and Walbaum, Arcb. Pharm., 231, 303; see also Minguin, Compt. rend., 123, 1296. 5 Baubigny, Ann. Chim. Phys. [4], 19 (1870), 221. eBrtihl, Ber., 24, 3377 and 3713. 144 THE TERPENES. Ethyl bornyl ether, C 10 H 17 OC 2 H 5 , is obtained by repeated treat- ment of a solution of borneol in xylene with sodium and ethyl iodide. It is a thick liquid having an unpleasant odor, and boils at 97° at 20 mm. and at 204° to 204.5° under 750 mm. pres- sure; its specific gravity is 0.9008 at 20°. A compound 1 called ethyl bornyl ether (?) is formed, together with camphene, by the action of alcoholic potash on pinene hydro- chloride ; it has a sp. gr. 0.9495 at 0° and a rotatory power, [*]„= + 26.3°. Methylene bornyl ether, (C 10 H 17 O) 2 CH 2 , is formed in a similar manner to the ethyl ether. It separates from ligroine in well formed, orthorhombic crystals, and melts at 167° to 168° (Brühl 2 ). Brühl has also examined the physical properties of this compound. Borneol, like other alcohols, combines with chloral and bromal to form compounds, which are analogous to the chloral-alcohol- ates. The borneol-chloral compound melts at 55° to 56°, and the bromal derivative melts at 98° to 99° (Haller 3 and Min- guin 4 ). Bornyl phenylurethane, C 6 H 5 NH-CO-OC 10 H iy , was first pre- pared by Leuckart 5 by the action of phenyl isocyanate on borneol. It melts at 138° to 139° (Bertram and Walbaum 6 ). The urethane and the above-mentioned compounds of borneol with chloral and bromal yield borneol on treatment with alco- holic potash. Bornyl xanthic acid, C 10 H 17 O • CS • SH, was obtained by Bam- berger and Lodter 7 by the action of carbon bisulphide on sodium bornylate, and analyzed in the form of its cuprous salt. Bornyl chloride, C 10 H 17 C1, was described by Kachler 8 as borneol chloride. It is most conveniently prepared by the following method. 9 Sixty grams (one molecule) of phosphorus pentachloride are placed in a flask fitted with a tube containing sulphuric acid to prevent access of moisture, and are covered with eighty cc. of very low boiling petroleum ether ; forty-five grams (one molecule) of borneol are added in small portions (about five to eight grams) 'Bouchardat and Lafont, Compt. rend., 104, 639. "Brühl, Ber., 24, 3377 and 3713. sHaller, Compt. rend., 112, 143. ^Minguin, Compt. rend., 116, 889. 6 Leuckart, Ber., 20, 115. 6 Bertram and Walbaum, Arch. Pharm., 231, 303. 'Bamberger and Lodter, Ber., 23, 214. sKachler, Ann. Chem., 197, 93. sWallach, Ann. Chem., 230, 231. BORNYL IODIDE. 145 at a time. After every addition of borneol a vigorous evolution of hydrochloric acid takes place, due to the action of the penta- chloride on the borneol, and a new portion of borneol is not added until this evolution of gas is finished. The operation is complete in about half an hour. The clear liquid is now poured off from any excess of phosphoric chloride into a thick-walled separating funnel of about one liter capacity, and the phosphorus com- pounds are removed by careful and frequent agitation with a large quantity of water. In case there is some doubt whether all of the phosphorus oxychloride is decomposed, the petroleum ether solu- tion of the bornyl chloride is eventually treated with alcohol, which is removed by shaking with water. The solution is poured into a shallow dish, and care is taken that the petroleum ether evaporates as quickly as possible in a cold place. Pure bornyl chloride is so obtained in a yield of about forty-five grams. It appears and smells like camphor, melts at 157°, and dis- solves readily in petroleum ether, less readily in alcohol, from which it may be obtained in thread-like crystals. It yields cam- phene when heated with aniline. According to Reychler, 1 and Jünger and Klages, 2 bornyl chloride is stereoisomeric with isobornyl chloride and camphene hydrochloride, the two latter being identical. According to Wagner, 3 most of the bornyl chloride, prepared as above described, is readily converted into camphene by boiling with alcoholic potash, and therefore consists chiefly of isobornyl chloride (camphene hydrochloride), the borneol being at first changed into camphene which then unites with one molecule of hydrogen chloride ; a small proportion of the bornyl chloride, how- ever, is not as easily acted upon by the alcoholic potash, and Wagner regards this as the true bornyl chloride, and that it is identical with pinene hydrochloride. Recent investigations by Semmler 4 also seem to indicate that pinene hydrochloride is the true chloride corresponding with borneol. Bornyl Iodide, C 10 H 17 I. — According to Wagner, 3 a mixture of bornyl iodide and another substance is formed when borneol is moistened with a little water and saturated with hydrogen iodide at the temperature of the water-bath ; the two compounds are sepa- rated by boiling with alcoholic potash for thirty hours, the bornyl 'A. Reychler, Ber., 29, 697; Bull. Soc. Chim., 15, 1896 (III.), 366. 2 Jünger and Klages, Ber., 29, 544. 3G. Wagner and Brickner, Ber., 32, 2302. 1:2.5 to 3, 1:6.5 to 7. Solubility in benzene at 20°, 1:1.5 to 2, 1 :4to 4.5. Solubility in petroleum ether at 0°, 1 :4to 4.5, 1 : 10 to 11. Solubility in petroleum ether at 20°, 1 : 2.5, 1:6. Phenylurethane, m. p. 138° -I to 139°, isoborneol is regenerated > by treat- ment with alcoholic potash, m. p. 138° 1 to 139°, borneol is regenerated > by treat- ment with alcoholic potash. Chloral compound, liquid, m. p. 55° to 56°, Bromal compound, m. p. 72°, m. p. 98° to 99°, „ Formyl ester, liquid, b. p. 100° (14 mm. ), liquid, b. p. 98° to 99° (15 mm. ). Acetyl ester, liquid, b. p. 107° (13 mm. ), m. p. 29° ; b. p. 106° to 107° (15 mm.). Behavior towards zinc chloride or dilute sul- phuric acid, forms camphene, unchanged. Behavior towards sul- phuric acid and methyl or ethyl alcohol. forms methyl or ethyl isobornyl ether, does not yield ethers by this treatment. 150 THE TEEPENES. ^ Isobornyl chloride, 1 C 10 H ir Cl, is obtained when hydrogen chlo- ride is led into an alcoholic solution of isoborneol. It melts at 150° to 152°, and is identical with camphene hydrochloride. A brief statement regarding the rotatory powers of the more im- portant derivatives of camphor is presented in the following. According to Beckmann, 2 camphor has the specific rotatory power, [a] D =± 44.22°. The direction and degree of rotation is not changed by heating camphor to high temperatures (230° to 250°), or by boiling it with alcohol or glacial acetic acid, or by dissolving in concentrated sulphuric acid. The same investigator finds that camphoroxime prepared from levo-camphor is dextrorotatory, whilst the oxime from dextro- camphor is levorotatory. He gives these values for the rotatory power of camphoroxime : Dissolved in 5 parts of alcohol, [a " " 12 " " " [«' D = - 42.4° and + 42.51°, j} ~ -41.38° and + 42.38°. Camphoroxime hydrochloride (m. p. 162°) has the specific ro- tatory power, [a] D = — 43.98° and + 42.52°. Borneol has a different rotatory power according to its origin ; thus Beckmann 3 found the rotatory power of d-borneol to be Mz» = + 37.44°, and Haller 4 determined the rotatory power of borneol regenerated from the crystalline acetate, [a] D = + 37.63°. Natural 1-borneol has [d] D = —37.74° (Beckmann 3 ), and — 37.77° (Haller 5 ) ; a 1-borneol occurring under the name of Ngai ßn has \a] D = - 39° 25' (Schimmel & Co. 6 ). According to Bertram and Walbaum, 7 the rotatory power of isoborneol changes under the influence of the sulphuric acid used in its preparation. This substance further shows a change in strength of its optical rotation when dissolved in different solvents. Isoborneol obtained from the camphene of citronella oil has the rotatory power : Dissolved in alcohol, [a\ D = + 4.71°. Dissolved in benzene, [«]#= + 2.88°. >A. Reychler, Ber., 29, 697; Bull. Soc. CMm., 15, 1896 (III.), 366; see also Jünger and Klages, Ber., 29, 544. 2 Beckmann, Ann. Chem., 250, 352. »Beckmann, Ann. Chem., 250, 353; Journ. pr. Chem. [IL], 55, 31. «Haller, Compt. rend., 109, 30; 112, 143. 6 Haller, Compt. rend., 108, 456; 109, 456. 6 Schimmel & Co., Semi- Annual Report, April, 1895, 76. 'Bertram and Walbaum, Journ. pr. Chem., 49, 14. ALDEHYDE FROM CAMPHENE GLYCOL. 151 4. CAMPHENE GLYCOL, C 10 H 16 (OH) 2 . Caraphene glycol is closely allied to borneol ; it was obtained by G. Wagner 1 by the oxidation of camphene with potassium permanganate. Seventy grams of camphene dissolved in twenty-five grams of benzene are added to six liters of a one per cent, solution of potassium permanganate. If the color of the permanganate is entirely removed after four hours of constant agitation, the mixture is allowed to stand for some time, and the clear alkaline solution removed in a current of carbon dioxide by means of Zulkowsky's suction apparatus. The residue consisting of manganese oxides is washed with water, and again shaken with four and one-half liters of a one per cent, solution of permanganate. After decol- orization, the liquid is removed as above suggested, and the manganese oxides are treated for a third time with three liters of permanganate. The filtrates thus obtained are saturated with carbonic anhydride, and extracted thirty times with benzene. The benzene is then distilled off, and a small amount of cam- phene which remains in the residue is driven over with steam ; camphene glycol is only slightly volatile with steam, and after the addition of potassium hydroxide to the aqueous residue it is extracted with ether. On evaporation of the latter the solid glycol is obtained, and repeatedly recrystallized from benzene. It separates in prismatic needles, which melt at 192°. It is very readily soluble in ether, alcohol, carbon bisulphide and chloroform, sparingly in benzene ; when thrown upon water it rotates in the same manner as camphor. It melts when warmed with water, and is only slightly soluble in hot water ; it sublimes very readily when heated above 100°. ALDEHYDE, C 10 H 16 O, FROM CAMPHENE GLYCOL. When camphene glycol is heated with hydrochloric acid, it loses one molecule of water, forming a solid substance which smells like camphor ; it has the formula, C 10 H 16 O, and is characterized as an aldehyde by its behavior towards fuchsinesulphurous acid and to- wards an ammoniacal silver solution. Hydroxylamine reacts with it, yielding a liquid compound ; bromine acts slowly upon its solu- tion in chloroform, giving rise to substitution products. When it is allowed to stand with water in the air, the water at once gives an acid reaction, and the substance becomes liquid* (Wagner ). (See camphenilanic acid, page 65.) iG. Wagner, Ber., 2S, 2311. 152 THE TERPENES. # This aldehyde is also formed iu small quantities in the prepara- tion of camphene glycol. According to recent investigations of Bredt and Jagelki 1 it seems probable that this aldehyde is identical with camphenilan aldehyde (m. p. 70°), which is formed by the action of water on the double compound of camphene with chromyl dichloride . Pin n ene fy™ 1 ' C io H 16 (OH) 2 , is described by Wagner ; it is men- tioned under pinene (see page 46). 5. CAMPHOL ALCOHOL, C ]0 H 19 OH. According to Errera, 2 if a solution of campholamine hydro- chloride be warmed with silver nitrite, camphol alcohol, 0 H OH is produced, together with a hydrocarbon, C 10 H 18 . This alcohol is a liquid having an agreeable odor, and boils at 203°. Since campholamine contains the group, — CH 2 NH 2 , it would be expected to yield a primary alcohol ; Errera, 3 however, de- termined by the speed of the ester formation that camphol alcohol is a tertiary alcohol. 6. CAMPHENONE, C 10 H 14 O. Claisen and Manasse 4 prepared amidocamphor by reduction of isonitroso-camphor, °' H "Co OH with zinc dust and acetic acid ; by treating amidocamphor with nitrous acid, Angeli 5 obtained diazo-camphor, MJ=0 which, according to Curtius' nomenclature, may be called mono- ketazo-camphor-quinone or monoketazocamphadione. When this substance is heated and the resultant product is distilled with steam, camphenone, C 10 H u O, is formed. It has an odor similar to that of camphor, and separates from petroleum ether in splendid colorless crystals, which melt at 168° to 170° (Angeli 6 ). 'Bredt and Jagelki, Ann. Chem., 810, 112. sErrera, Gazz. Chim., 22 [2], 114; Ber., 26, 21, Ref. "Errera, Gazz. Chim., 23 [2], 497; Ber., 27, 126, Ref. «Claisen and Manasse, Ann. Chem., 274, 88. s Angeli, Ber., 26, 1718; Rimini, Gazz. Chim., 26 [2], 290. e Angeli, Gazz. Chim., 21 t [2], 44 and 317; Ber., 27, 590, 797 and 892 ISOCAMPHENONE. 153 Camphenone behaves as an unsaturated compound ; it is im- mediately oxidized by a permanganate solution, and is reduced to camphor by the action of nascent hydrogen. Camphenone hydrobromide, 1 C 10 H 14 O • HBr, is produced by treat- ing camphenone with hydrogen bromide in a glacial acetic acid solution ; it is isomeric with monobromocamphor. It melts at 113°, is stable towards acids, but is converted into camphenone by alkalis, and yields camphenonoxime on treatment with an alka- line solution of hydroxylamine. Camphenone dibromide, 1 C 10 H H O • Br 2 , is formed by the addition of bromine to a solution of camphenone in carbon bisulphide ; it is isomeric with dibromocamphor, but is readily distinguished from the latter by yielding monobromocamphenone on treatment with alcoholic potash. It separates from alcohol or petroleum in large crystals, and melts at 58° to 59°. Monobromocamphenone, C 10 H 13 BrO, is obtained by treating camphenone dibromide with alcoholic potash ; it forms large, well denned crystals, melting at 70°. Camphenonoxime, 2 C 10 H 14 NOH, is formed by the action of hydroxylamine on camphenone; it crystallizes from petroleum ether in tablets, and melts at 132°. It is isomeric with nitro- sopinene, and melts at the same temperature as the latter.^ By the action of mineral acids it is gradually converted into a nitrile. Pernitrosocamphenone, 2 C 10 H H N 2 O 2 , is prepared by the action of nitrous acid on camphenonoxime ; it melts at 47°, is insoluble in acids and alkalis, and does not give the Liebermann's reaction. Pernitrosocamphenone dibromide (dibromopernitrosocamphor), C 10 H 14 N 2 O 2 -Br 2 ,is produced by the addition of bromine to a chlo- roform solution of pernitrosocamphenone. It crystallizes from petroleum and melts at 133°. Isocamphenone, C 10 H 14 O. — When pernitrosocamphor, C 10 Hj 6 N 2 O 2 (obtained by the action of nitrous acid on camphoroxime), is dis- solved in a glacial acetic acid solution of dry hydrogen bromide, and is then treated with bromine, bromopernitrosocamphor, C 10 H 15 - BrN0 2 (m. p. 114°), is formed; this is converted into isobromo- pernltrosocamphor, C 10 H 15 BrN 2 O 2 (m. p. 67°), by the action of di- lute alcoholic potash. When the latter compound is treated with cold, concentrated sulphuric acid, isocamphenone is obtained ; it separates from petroleum in yellowish crystals, melts at 92°, and soon resinifies in the air. Its oxime melts at 170°. JAngeli and Rimini, Atti. d. R. Acc. d. Lincei Rudct., 1895 [1], 390; Gazz. Chim., 26 [2], 34 and 45. «Angeli, Gazz. Chim., 24 [2], 44 and 317; Angeli and Rimini, Gazz. Chim., 26 [2], 34 and 45; Ber., 28, 1077. 154 THE TERPENES. 7. PINOCAMPHONE, C 10 H 16 O. This ketone, which is isomeric with camphor, is formed aß a by-product in the preparation of pinylamine, C l0 H I5 NH 2 , from nitrosopinene, C 10 H 1? NOH. Wallach 1 observed the formation of this ketone during his first researches on the reduction-products of nitrosopinene, but it was not until the year 1898 that he pub- lished a detailed account of its method of preparation and its properties. 2 Pinocamphone is prepared by the following method. Five grams of nitrosopinene are dissolved in forty cc. of warm glacial acetic acid, and, after diluting with sufficient water to pro- duce a slight cloudiness, the solution is treated with a large excess of zinc dust. After the first violent reaction has ceased, the mixture is heated in a reflux apparatus on the water-bath for three or four hours. The excess of zinc is then removed by fil- tration, the filtrate is distilled with steam, and the distillate is extracted several times with ether ; the ethereal solution is dried with solid potash, the ether is distilled off, and the residue is fractionated in vacuum. The yield of pinocamphone is over twenty per cent, of the nitrosopinene employed. The odor of pinocamphone is somewhat similar to that of tur- pentine, but on warming it suggests that of peppermint oil. It boils at 211° to 213°, has the specific gravity 0.959, and the re- fractive index, n^ = 1.47273, at 21°; its molecular refraction is 44.44, while that calculated for the compound, CLH,/), is 44.11. 10 16 Pinocamphonoxime, C 10 H 16 NOH, is readily obtained, and is char- acterized by its splendid power of crystallization. It is volatile with steam, crystallizes in large, transparent plates, and melts at 86° to 87°. On reduction with sodium and alcohol, it yields pinocamphylamine? C 10 H 17 NH 2 , which is a liquid ; it rapidly absorbs carbon dioxide, forms a carbamide (m. p. 204°), and an acetyl derivative (m. p. 120°). Pinocampholenonitrile, C 10 H 15 N. — Pinocamphonoxime is not at- tacked by boiling dilute sulphuric acid. When the oxime is boiled for a considerable time with concentrated sulphuric acid (one part acid to one part water), a small proportion is converted into a nitrile, while much of the oxime remains unaltered. The nitrile is obtained by distilling the reaction-product with steam. •Wallach, Ann. Chem., 268, 210. 2 Wallach, Ann. Chem., 800, 287. 3 Wallach, Ann. Chem., 813, 345. FENCHONE. 155 The nitrile 1 is an oil, having an odor similar to that of campho- lenonitrile, and is volatile with steam ; it boils at 224° to 226°. It is converted into pinocampholenic aeid, C 10 H 16 O 2 , by heating with alcoholic potash ; this acid yields an amide melting at 116°. Pinocamphone semicarbazone melts at 199° to 200°. Wallach is inclined to regard pinocamphone, C 10 H l6 O, as the dihydro-derivative of an unknown ketone, C 10 H u O, which cor- responds with nitrosopinene, C 1( ,H 14 NOH. A ketone, C 10 H 16 O, isomeric with pinocamphone, is formed when nitrosopinene dibromide is reduced with zinc and acetic acid in exactly the same manner as described above. This compound is an oil, having an odor similar to that of carvone. It yields an oxime, which crystallizes from dilute alcohol in needles, and melts at 113° to 114°. The properties of this isomeric ketone and of its oxime re- semble so closely those of inactive dihydrocarvone, that Wallach is inclined to consider the ketone as identical with inactive dihy- drocarvone. 8. PINOCAMPHEOL, C 10 H 17 OH. This alcohol, isomeric with borneol, is prepared by reducing pinocamphone with sodium in aqueous ether according to Beck- mann's method of reducing camphor to borneol. It is a viscous liquid, having the odor of terpineol and turpen- tine. It boils at 218° to 219°, has the specific gravity 0.9655, and the refractive index, n^ 1.48612, at 20°. When it is heated with zinc chloride, it loses water and yields products among which cymene has been identified. Pinocamphyl phenylurethane, /NHC 6 H 5 CO \OC 10 H 17 forms a crystalline mass, and melts at 98°. 9. FENCHONE, C 10 H 16 O. Fenchone occurs in nature in a dextrorotatory and a levorota- tory modification, and in its total behavior shows the greatest sim- ilarity to camphor. Dextro-fenchone is present in fennel oil, 2 while levo-fenchone forms a constituent of thuja oil. 3 »Wallach, Ann. Chem., 813, 345. »Wallach and Hartmann, Ann. Chem., 259, 324. sWallach, Ann. Chem., 272, 102. 156 THE TEKPENES. The fractions boiling between 190° and 195° of fennel oil and thuja oil consist almost wholly of fenchone. Its purification is easily accomplished, since fenchone is much more stable towards oxidizing agents than the substances accompanying it. However, the compounds occurring with fenchone in fennel oil differ in character and in quantity from those found in thuja oil, hence the two oils cannot be treated in the same manner. Preparation of Dextrorotatory Fenchone. 1 — The fraction of fennel oil boiling at 190° to 195° contains considerable quantities of anethol and other impurities, even after repeated distillations. Two hundred grams of this fraction are heated with three times its amount of ordinary concentrated nitric acid in a large flask connected with a reflux condenser, over a free flame. A vigorous reaction takes place, accompanied by evolution of nitrogen oxides. At this point, it is well to somewhat diminish the heat in order to prevent a too violent action. The mixture is then warmed until the fumes, which are at first reddish brown in color, are light colored. It is then allowed to cool; the contents of the flask are poured into water, and the resulting oil is separated. This oil is washed with a solution of sodium hydroxide, distilled with steam, and the fenchone obtained in the distillate is dried with potash ; the product is now quite pure. It is then cooled in a freezing mixture and brought to crystallization by the addi- tion of a small crystal of pure fenchone. Large crystals of pure fenchone separate, and are filtered from the residual oil. The fraction boiling at 190° to 195° of thuja oil contains a much smaller quantity, about twenty to twenty-five per cent., of fenchone. Thujone isthe chief constituent of this fraction. Pure levorotatory fenchone is prepared by one of three follow- ing methods (Wallach 2 ). 1. Oxidation with Nitric Acid. _ To eighty cc. of hot concentrated nitric acid contained in a capa- cious flask provided with a reflux condenser (the tube of the condenser should be sealed onto the flask), twenty cc. of the above- mentioned fraction of thuja oil are added drop by drop. After all of the oil has been introduced, the mixture is boiled for an hour, and then distilled with steam j the resulting oil is washed with sodium hydroxide, again distilled with steam, and the pure levo-fenchone is crystallized by the method suggested above. 'Wallach, Ann. Chem., 263, 130. 2 Wallach, Ann. Chem., 272, 102. FENCHONE. 157 2. Oxidation with Permanganate. Levorotatory fenchone and thujaketonic acid may be very con- veniently prepared at the same time. For this purpose, one hun- dred and thirty grams of the fraction of thuja oil boiling at 190° to 200° are shaken with a solution of three hundred and ninety grams of potassium permanganate in five liters of water, until the permanganate solution is decolorized ; some form of shaking ma- chine is employed to constantly agitate the mixture. The un- changed oil is distilled with steam, separated and treated with hot nitric acid according to methocLl. By this operation larger quan- tities of levo-fenchone may be obtained in one treatment. 3. Treatment with Dilute Sulphuric Acid. The thujone in thuja oil may be more readily separated from levorotatory fenchone by heating the fraction of this oil boiling at 190° to 200° with dilute sulphuric acid (one volume of concen- trated acid with two volumes of water). Thujone is so converted into isothujone, which boils 30° higher than thujone, while fen- chone remains unchanged (Wallach *). Fenchone is further obtained by boiling fenchyl alcohol with three times its amount of nitric acid. 2 The product thus formed has the same optical rotation, respecting direction and power, as the fenchone from which the alcohol is prepared by reduction. Properties. 3 — The properties of dextro- and levo-fenchone agree completely with the exception of the opposite rotatory powers. Wallach found the specific rotatory powers as follows : Dextro-fenchone (chemically pure) = + 71.97°. Levo-fenchone (not absolutely pure) = — 66.94°. Inactive fenchone, 4 prepared by mixing equal parts of dextro- and levo-fenchone, has the same properties as its active compo- nents, but its derivatives, however, often differ considerably from the corresponding active compounds in melting points, forms of crystals and solubilities. Inactive fenchone bears the same rela- tion to its active constituents as racemic acid does to the dextro- and levo-tartaric acids. Pure fenchone is an oil, smells like camphor, boils at 192° to 193°, and has the sp. gr. 0.9465 at 19° ; its refractive index is np = 1.46306 at 19°, corresponding to a molecular refraction of 'Wallach, Ann. Chem., 286, 103. ^Wallach, Ann. Chem., 263, 146. sWallach, Ann. Chem., 263, 131 ; 272, 103. 'Wallach, Ann. Chem., 272, 107. 158 THE TEBPENES. 44.23 while the calculated value for a compound of the compo- sition, C 10 H 16 O, containing no ethylene linkage, is 44.11. It solidifies at alow temperature, and melts at 5° to 6°. Fenchone is a saturated compound. It combines with bromine in a cold petroleum ether solution, yielding a red, crystalline, un- stable additive product which is reconverted into fenchone on treatment with alkalis. Substitution takes place if bromine acts upon fenchone for a long time, or at a high temperature. Fenchone is quite readily dissolved by cold concentrated hy- drochloric acid or sulphuric acid, and is thrown out of this solu- tion on the addition of water. When it is warmed with strong sulphuric acid at about 80°, sulphur dioxide is given off and acetoxylene, C 10 H 12 O [CH 3 : CH 3 : CH 3 CO = 1 : 2 : 4] , is formed ; this is an oil, smelling somewhat of cinnamon. It boils at 131° at 20 mm. pressure, yields an oxime, melting at 86° to 87°, and is converted into para-xylic acid, C 9 H 10 O 2 , by oxidation (Marsh 1 ). With fuming nitric acid fenchone forms a clear mixture without any apparent reaction, and is precipitated unchanged by water. It may even be boiled with fuming nitric acid without visible change ; by long continued boiling it is acted upon by nitric acid, being converted into a mixture of organic acids. Thus, ac- cording to Gardner and Cockburn, 2 when fenchone is heated with concentrated nitric acid on the water-bath for six days, it is oxidized to isocamphoronic acid, C 9 II 14 0 6 (m. p. 163° to 164°), dimethyltricarballylic acid, C 8 H 12 0 6 (m. p. 152°), dimeth- ylmalonic acid, C 5 H g 0 4 (m. p. 190°), isobutyric acid, and acetic acid; in addition to these acids a nitrofenchone, C 10 H 15 O-NO 2 , is formed. The latter is an oil, which boils at 146° to 151° under 14 mm. pressure, and, on reduction with stannous chloride, yields an amine. Fenchone is more vigorously attacked by heating with three times its amount of fuming nitric acid in a sealed tube at 120° ; hydrocyanic acid is one of the products of this reaction. Potassium permanganate oxidizes fenchone to a mixture of acetic, oxalic and dimethylmalonic acids (Wallach 3 ). When phosphorus pentachloride is allowed to act upon fen- chone for six weeks in the cold, and the product is subsequently treated with water, chlorofenchene-phosphoric acid, C 10 H 14 C1PO- (OH), melting at 196°, a- and ß-chlorofenchene hydrochlorides, 1 J. E. Marsh, Journ. Chem. Soc, 75, 1058; compare with Claus, Journ. pr. Chem., 41 (II.), 396; Armstrong and Kipping, Journ. Chem. Soc, 63, 75. 2 Gardner and Cockburn, Journ. Chem. Soc, 78, 708. 3Wallach, Ann. Chem., 26'.?, 134. TRIBROMOFENCHONE. 159 C 10 H 16 C1 2 , and chlor of enchene, C 10 H 16 C1, a solid, boiling at 80° to 83° under 16 mm. pressure, are produced. 1 Bromofenchone, 2 C 10 H 15 OBr, is formed by heating fenchone with bromine for twenty hours at 100° in a sealed tube ; it is a color- less oil which boils at 131° to 134° under 18 mm. pressure, has a faint camphor-like odor, a sp. gr. 1.348 at 12°, a refractive index 1.51013, and a rotation + 11.6° in a 100 mm. tube. It is not readily volatile with steam, and yields neither an oxime nor a semicarbazone. Fenchone is regenerated by heating the com- pound with zinc dust and acetic acid. When bromofenchone is heated with an excess of alcoholic potash, a-fencholenic acid, C 10 H 16 O 2 ,is produced, identical with that obtained by Wallach ; when cooled with liquid air, it crystallizes. An isomeric compound? C 10 H 16 O 2 , is formed by dissolving the acid in concentrated sulphuric acid and pouring the solution on ice ; it crystallizes from light petroleum in leaflets, melts at 77°, is not soluble in solutions of sodium carbonate or hydroxide, and does not decolorize solutions of permanganate. (See "Biological Oxidation of Fenchone." Kimini, Atti. Real. Accad. Lincei, 1901 [V.], 10 (I.), 244.) Tribromofenchone, 3 C 10 H 15 OBr • Br 2 , is obtained by gradually adding bromine to a solution of fenchone in phosphorus tri- chloride ; it is a yellow oil, boils at 181° to 186° under 18 mm. pressure and darkens in the air. When tribromofenchone is boiled with zinc dust and acetic acid, it yields a crystalline compound, C 10 H 15 Br, melting at 115° to 116° ; it has a camphor-like odor, and in general properties re- sembles the chlorofenchene above mentioned. It sublimes readily and decolorizes permanganate. Tetrahydrofenchene, 4 C 10 H 20 , results when fenchone is heated with phosphorus and hydriodic acid ; the same hydrocarbon is ob- tained from fenchyl alcohol under analogous conditions. That fenchone is a ketone follows from the formation of fenchonoxime and fenchyl alcohol. On heating fenchone with ammonium formate according to Leuckart's method, fenchyl- amine, C 10 H 17 NH 2 , a base isomeric with bornylamine, is formed. It differs from camphor in that it does not form an oxymeth- ylene compound. 5 iGardner and Cockburn, Journ. Chem. Soc, 11, 1156; 18, 704. zCzerny, Ber., 33, 2287; see Balbiano, Gazzetta, 30 [IL], 382. sCzerny, Ber., 83, 2287. 'Wallach, Göttinger Nachrichten, 1891, 309; Ann. Chem., 284, 326. sWallach, Ber., 28, 34. 160 THE TERPENES. The behavior of fenchone towards phosphorus pentoxide is of especial interest in showing the resemblance of the reactions of fenchone and of camphor. According to Wallach, 1 twenty grams of fenchone and thirty grams of phosphorus pentoxide were well mixed in a small, round flask, and, after a further addition of thirty grams of phosphorus pentoxide, the mixture was heated for thirty minutes in a paraffin-bath at 115° to 130°. After cooling, water was carefully added and the resulting oil identified as meta-cymene, boiling at 175° to 176°. A comparison was made of this cymene with meta-cymene isolated by Kelbe from the distillation products of colophonium and resin oil, and they were found to be identical. Since para-cymene is formed by the action of phosphorus pen- toxide on camphor, and nearly all of the properties of cam- phor closely resemble those of fenchone, it is probable that these two substances bear the same relation to each other that a para- compound does to a meta-compound. It may also be mentioned that by oxidation of dextrorotatory and inactive fenchyl alcohols, obtained by Bouchardat and La- font 2 by the action of benzoic acid and other acids on French (levo rotatory) turpentine, levorotatory and inactive fenchones are obtained ; the former is the optical antipode of d-fenchone prepared from oil of fennel. This synthetically prepared 1-fen- chone forms an oxime (m. p. 161° to 163°), but it is produced less readily than that obtained from the fenchone prepared from oil of fennel. Fenchone does not react with alkaline bisulphites. Fenchone semicarbazone, 3 C 10 H 16 • N NH CO -NH 2 , cannot be prepared directly from fenchone and a semicarbazide solution. It is formed, however, by gently heating pernitrosofenchone, C 10 H 16 N 2 O 2 , with semicarbazide acetate on the water-bath. It separates from alcohol in white crystals, and melts at 186° to 187°. Fenchonoxime, C 10 H 16 NOH, is conveniently prepared in small quantities by the following method (Wallach 4 ). To five grams of fenchone dissolved in eighty cc. of absolute alcohol, a solution of eleven grams of hydroxylamine hydrochloride in eleven grams of hot water and six grams of pulverized potash are added. The spar- ingly soluble oxime separates in the course of one or two days by the gradual evaporation of the alcohol. 1 Wallach, Ann. Chem., 275, 157. 2 Bouchardat and Lafont, Compt. rend., 126, 755. sRimini, Gazz. Chim., 30 (I.), 600. «Wallach, Ann. Chem., 284, 324; 272, 104. FENCHONOXIME ANHYDRIDE. 161 For the preparation of larger quantities of fenchonoxime, Wallach 1 employs the following method. One hundred grams of fenchone are dissolved in four hundred grams of absolute alcohol and treated with a warm solution of eighty grams of hydroxyl- amine hydrochloride in eighty grams of water. The solution is then rendered alkaline by the addition of fifty grams of potassium hydroxide dissolved in fifty grams of water ; the potassium chlo- ride is filtered off, and the filtrate boiled for a few hours on the water-bath. A large quantity of the oxime separates out on cool- ing. An additional amount may be obtained by warming the mother-liquor, and precipitating with water. 2 Fenchonoxime crystallizes from alcohol in fine needles, and from ethyl acetate or ether in well formed, monoclinic 3 crystals, which melt at 161° when heated rapidly. 4 It is volatile with steam, and boils at 240° with slight decomposition (elimination of water). It is insoluble in sodium hydroxide. The oxime of dextro-fenchone is dextrorotatory, 5 [a] D = 52.54° ; that obtained from levo-fenchone is levorotatory. Inactive fenchonoxime is formed by mixing the ethereal solu- tions of equal parts of dextro- and levorotatory oximes ; it sepa- rates in crystals which differ in form from those of the active modifications, and melt slightly lower than these, at 158° to 160°. Wallach and Hartman obtained fenchonoxime hydrochloride by precipitating an ethereal solution of the dextro-oxime with hy- drochloric acid ; it melts at 118° to 119°. Fenchylamine, C 10 H 17 NH 2 , analogous to bornylamine, is pre- pared by reducing fenchonoxime with sodium and alcohol. Fenchonoxime anhydride, 6 C 10 H 15 N ( a- and /?-fencholenonitrile, C g H 15 • CN), is formed very easily and quickly by the action of de- hydrating agents on fenchonoxime. When the oxime is dissolved in warm, dilute sulphuric acid, a clear solution is at first obtained, but if this be heated to a higher temperature, fenchonoxime anhy- dride separates at once as an oil, which may be readily distilled with steam. iWallach, Ann. Chem., 268, 136. 2 For preparation of fenchonoxime, see also Rimini, Gazz. Chim., 26 (II.), 502. »Zander, Ann. Chem., 259, 327. *Mahla and Tiemann (Ber., 29, 2807) give the melting point of the active modifications at 163°; Rimini (Gazz. Chim., 26 (II.), 502) finds them to melt at 165°. «Wallach and Binz, Ann. Chem., 276, 317; 272, 104. 6 Wallach and Hartmann, Ann. Chem., 259, 328; Wallach, Ann. Chem., 268, 137. 11 162 THE TERPENES. The anhydride prepared from dextro-fenchonoxime is dextro- rotatory, [a] D = + 43.31°. It boils at 217° to 218 0 , 1 has a spe- cific gravity 0.898 and the refractive power, n^ = 1.46108, at 20°. Although fenchone and fenchonoxime are saturated compounds, the anhydride is unsaturated, and forms a liquid bromide when treated with bromine ; it also combines with hydrobromic and hy- driodic acids, forming the solid, but unstable, addition-products, C 10 H 15 N HBr and C 10 H 15 N HI. These two compounds can only be crystallized from alcohol when great care is taken ; the hydro- bromide melts at 60°, and hydriodide at 54° to 55°. Hydrochlorofenchonoxime anhydride, C 10 H 15 N-HC1, is more stable than the hydrobromide and hydriodide, and is prepared by shak- ing the anhydride with concentrated hydrochloric acid ; after a short time the product becomes solid, is pressed on a porous plate, and recrystallized from petroleum ether. The pure hydrochloride melts at 57° to 58°, and decomposes into its constituents on boil- ing with water or alcohol (Wallach 2 ). Fenchonoxime anhydride is to be regarded as a nitrile, C 9 H 16 CN, since it may be converted into a- and /?-fencholenic acids, CgH^COOH, and a-fencholenamide ; the latter is identical with a-isofenchonoxime. When it is reduced with sodium and alcohol, an unsaturated base, fencholenamine, 3 C 10 H 17 NH 2 , is formed ; this amine is isomeric with camphylamine. a-Isofenchonoxime, C 10 H 17 NO (a-fencholenamide, C g H 15 CONH 2 ). The transformation of fenchonoxime anhydride into the corre- sponding acid amide, and more especially into the acid itself, is effected much more slowly than the like transformation of camphor- oxime anhydride into a-campholenamide and a-campholenic acid. a-Isofenchonoxime is prepared by warming thirty grams of fenchonoxime anhydride with a solution of 130 grams of potas- sium hydroxide in 450 cc. of absolute alcohol and twenty cc. of water for four or five days. A small quantity of ammonia is constantly given off, thus forming fencholenic acid, but the greater part of the anhydride is converted into a-isofenchonoxime. The solution is diluted with water, and the alcohol is removed by dis- tillation ; on cooling, yellowish, crystalline leaflets are obtained, which are purified by boiling with animal charcoal and recrystal- lizing from alcohol. It melts at 113° to 114°, and dissolves in 1 According to Cockburn (Journ. Chem. Soc, 75, 503), it boils at 214° to 219°. 2 Wallach, Ann. Chem., 269, 330. 3 Wallach and Jenkel, Ann. Chem., 260, 369. «-FENCHOLENIC ACID. 163 alcohol, ether and acids ; it may be reprecipitated from an acid solution by alkalis (Wallach 1 ). a-Fencholenic acid, a-isofenchonoxime and a-fencholenonitrile, which is produced by gently warming a-isofenchonoxime with phosphoric anhydride, are unsaturated compounds. The a-isox- ime is optically active. When the solutions of equal quantities of dextro-and levo- a-isofenchonoxime are mixed, an inactive modification is formed, which melts at 98° to 99°. If the a-isoxime be reduced in an alcoholic solution with sodium, tt-fencholenic acid and a-fencholenamine are formed, to- gether with isofencholenyl alcohol (see page 176). /9-Isofenchonoxime, 2 C 10 H 17 NO, is a saturated compound, and is obtained when a-isofenchonoxime is boiled for several hours with dilute sulphuric acid. By this treatment the a-isoxime is grad- ually dissolved, and when the cold solution is neutralized with alkali, /9-isofenchonoxime is precipitated as a white, crystalline substance, which is more readily soluble in hot water than the isomeric a-compound. It is readily soluble in alcohol, from which it may be recrystallized ; it melts at 137°, has pronounced basic properties and is probably a lactam. (See dihydrofencho- lenic acid lactam.) By the oxidation of a sulphuric acid solution of the /9-isoxime with permanganate, dimethylmalonic acid is formed ; therefore, it has in all probability the same atomic structure as fenchone. /9-Isofenchonoxime is optically active; an inactive modifica- tion may be obtained, and melts at 160° to 161°. The hydrochloric acid salt is prepared by precipitating an ethereal solution of the /9-isoxime with hydrogen chloride ; it soon loses hydrochloric acid by standing in the air. The sulphate, obtained by treating the ethereal solution of the /9-isoxime with concentrated sulphuric acid, forms brilliant needles. a-Fencholenic acid, 3 C 9 H 15 COOH, is formed, as indicated above, by the saponification of fenchonoxime anhydride or of a-isofen- chonoxime with alcoholic potash ; it is obtained from the alkaline solution, from which some unchanged a-isofenchonoxime also crystallizes. For the complete separation of the latter, the alka- line solution is shaken with ether, and then evaporated to such a degree of concentration that the liquid separates into two layers; the upper, dark-colored layer, which contains the fencholenic acid salt, is separated from the lower one, consisting for the most part i Wallach, Ann. Chem., 269, 332; 259, 330; 315, 273. 2 Wallach, Ann. Chem., 269, 332; 284, 333. »Wallach, Ann. Chem., 269, 334; 259, 330. 164 THE TERPENES. of potassium hydroxide, and is acidified with sulphuric acid after proper dilution with water. The liquid a-fencholenic acid is com- pletely removed from the acid solution by means of ether, and is distilled in a current of hydrogen. It boils at 260° to 261°, and has the specific gravity 1.0045 at 16°; its coefficient of refraction is 1.4768 at 16°, corresponding to the molecular refraction 47.24. By the action of sodium hypobromiteon thecold solution of sodium a-fencholenate, a brominated lactone 1 is formed, which melts at 76°. Silver a-fencholenate, C 10 H ]5 O 2 Ag, is sparingly soluble in water and alcohol. The salts of the alkali metals and of the alkaline earths are not characteristic. Ammonium a-fencholenate yields a-isofenchonoxime (a-fencholenamide), when heated in a sealed tube at 205° to 210°. a-Fencholenic acid is unsaturated, and when shaken with hydro- gen iodide or chloride it forms solid addition-products. Hydrochlorofencholenic acid, C 10 H 17 ClO 2 , prepared by shaking a-fencholenic acid with concentrated hydrochloric acid, separates from petroleum ether in small, hard crystals, and melts at 97° to 98°. The hydrobromide, 2 C I0 H 17 BrO 2 , melts at 96° to 100°. a-Fencholenic acid is immediately oxidized by a cold solution of potassium permanganate with the production of an acid, which has a syrup-like consistency. The electrical conductivity of a-fencholenic acid has been de- termined by Binz. 3 When sodium a-fencholenate is distilled with soda-lime, it gives a complicated mixture of hydrocarbons and compounds containing oxygen (Wallach). A saturated hydrocarbon is formed when a-fencholenic acid is reduced by heating with phosphorus and concentrated hydriodic acid at 180° to 200° ; this compound distills almost completely at 138° to 145°, and the analyses and determinations of its vapor density indicate that it consists chiefly of dihydrofencholene, C 9 H lg . Dihydrofencholene boils at 140° to 141° ; its specific gravity is 0.790 and refractive power, n^ = 1.43146, at 20°. The same hydrocarbon is also obtained by reducing fenchonoxime anhydride in like manner. The formation of this hydrocarbon shows that fencholenic acid and fencholenonitrile possess a closed carbon chain. According to the investigations of Cockburn, 4 a second series iWallach, Ann. Chem., 315, 273. 2 Cockburn, Journ. Chem. Soc, 75, 506. 3Binz, Ann. Chem., 269> 338. 4 Cockburn, Journ. Chem. Soc, 75, 501. Wallach has also confirmed these observations, see Ann. Chem., 315, 273. /9-FENCHOLENIC ACID. 165 of isomeric substances is derived from fenchonoxime ; Cockburn designates these as beta-compounds. /3-Fencholenonitrile, C 9 H 15 -CN. — According to Cockburn, the fencholenonitrile, prepared as described under fenchonoxime anhydride by the action of dilute sulphuric acid on fenchonoxime, is a mixture of the a- and /9-nitriles, and boils at 214° to 219° ; on saponification it yields a- and /3-fencholenic acids. The pure a-nitrile may be prepared from a-isofenchonoxime (m. p. 113° to 114°) ; it boils at 211° to 212°, has the sp. gr. 0.9136 at 15.6°, and the specific rotatory power [a] i> = -f- 28.98°. On boiling with alcoholic potash, it is readily converted into the a-amide (a-isofenchonoxime, m. p. 113° to 114°), but only with difficulty into the liquid a-fencholenic acid. Pure ß-fencholenonitrile, prepared from the /?-amide by warm- ing with phosphorus pentoxide, is a colorless liquid, boils at 217° to 219°, has the specific gravity 0.9203 at 15.6°, and the speci- fic rotatory power, = + 43.66°. It is quantitatively and very readily converted into /3-fencholenic acid on hydrolysis, but ap- parently cannot be changed into the /9-amide by the action of alcoholic potash. /2-Fencholenamide, C 9 H 15 -CONH 2 . — By the hydrolysis of the mixture of nitriles, formed in the dehydration of fenchonoxime, only the a-amide melting at 113° to 114° can be obtained. The /3-amide is produced, however, by heating the ammonium salt of /9-fencholenic acid in a sealed tube, at 180°, for five hours ; it is readily soluble in ether and alcohol, and crystallizes from a mixture of alcohol and light petroleum in soft, silky needles, melt- ing at 86.5° to 87.5°. /?-Fencholenic acid, 1 C 9 H 15 -COOH, is prepared by the hydrolysis of the mixture of a- and /3-nitriles by heating with alcoholic pot- ash for two and one-half days ; all of the /9-nitrile is thus con- verted into the /9-acid while only a small quantity of the a-acid is produced, owing to the difficulty with which the a-amide is saponified. The a-amide which is formed is separated, and can be used for the preparation of the pure a-acid. The yield of the /3-acid is about 55 to 60 per cent., and of a-amide 35 per cent, of the theoretical, the remainder being the a-acid. /?-Fencholenic acid is purified by recrystallization from light petroleum ; it melts at 72° to 73°, boils without decomposition at 259° to 260°, and has the specific rotatory power, [a] i) = -j- 19.64°. It is readily soluble in alcohol, ether, and acetone, less so in benzene and glacial acetic acid. It is an unsaturated acid, 'Cockburn, Journ. Chem. Soc, 75, 503; see Wallach, Chem. Centr., 1899 (IL), 1052; Nachr. k. Ges. Wiss. Göttingen, 1899, No. 2. 166 THE TEKPENES. and immediately decolorizes bromine and permanganate solutions. Its salts of the alkali metals are not very characteristic, but the salts of the alkaline earths are well defined, crystalline com- pounds, thus differing from the corresponding salts of the a-acid. /9-Fencholenic acid yields a brominated lactone, 1 melting at 80°, by the action of sodium hypobromite on the cold solution of the sodium salt. According to Cockburn, pure a-fencholenic acid, prepared by the hydrolysis of the a-amide, melting at 113° to 114°, boils with slight decomposition at 254° to 256°, has the specific gravity 1.0069 at 16°, and the specific rotatory power, [a] D = + 30.73°. Hydrobromo-/?-fencholenic acid, C 10 H 17 BrO 2 , is formed during the action of bromine on a solution of the /?-acid in petroleum ether, cooled by a freezing mixture. It crystallizes from light petroleum in long, thin needles, and melts without decomposition at 80° to 81°. The Action of Nitrous Acid upon Fenchonoxime. 2 According to Mahla and Tiemann, when an ethereal solution of fenchonoxime is treated with nitrous acid, two compounds are formed ; one is insoluble in ether, and is termed fenchonimine ni- trate, C 10 H 17 N-HNO 3 , melting at 152°, while the other remains in the ethereal liquid after separation of the nitrate, and is called fenehonitrimine, C 10 H 16 N 2 O 2 , melting at 58°. According to Angeli and Rimini, when a dilute hydrochloric acid solution of fenchonoxime is treated with sodium nitrite, per- nitrosofenchone, C 10 H 16 N 2 O 2 , is obtained ; it crystallizes in trans- parent scales, melts at 66° to 67°, and is probably identical with Tiemann's fenehonitrimine. It is converted into fenchone by heating with alcoholic potash, but when treated with cold alcoholic potash or ammonia, it is changed into isopernitrosofenchone, C 10 - H lg N 2 0 2 ; this compound melts at 88°. Pernitrosofenchone and its isomeride are both converted into isocamphor, C 10 H 16 O, by treatment with concentrated sulphuric acid ; isocamphor is an oil, boiling at 216°, and yields an oxime (m. p. 106°), and a semicar- bazone(m. p. 215°). When pernitrosofenchone and semicarbazide acetate are heated on the water-bath, fenchone semicarbazone (m. p. 186° to 187°) is obtained. Fenchimine, 3 C ]0 H 16 • NH, results by the action of twenty-five per cent, aqueous ammonia on fenehonitrimine, C 10 H 16 lSr 2 O 2 . It Wallach, Ann. Chem., 815, 273. 2 Mahla and Tiemann, Ber., 29, 2807 ; Angeli and Rimini, Gazz. Chim., 26 [II.], 228; Rimini, Gazz. Chim., 26 [II.], 502; SO [I.], 600. »F. Mahla, Ber., 3J h 3777. OXYDIHYDROFENCHOLENAMIDE. 167 boils at 83° (15 mm.), has the specific rotatory power, [a\ D == + 76.3°, at 19.5° (10 cm. tube), sp. gr. is 0.9322 at 11.5°, re- fractive index is n D = 1.47809 at 17°, and the molecular re- fraction 45.78. It is a strong base and forms crystalline salts ; the picrate forms splendid crystals and melts at 202° ; the hydro- chloride melts at 278°, and on heating to 180° for eight hours is decomposed with the formation of cymene. Methylfenchimine iodide forms well defined crystals. When a current of dry air is passed through warm, pure fenchimine, it is converted into dihydrofencholenonitrile and oxy- dihydrofencholenonitrile. Dihydrofencliolenonitrile, C 9 H 17 • CN, is formed by leading a cur- rent of dry air through fenchimine heated in an oil-bath at 105° ; after the action has continued for thirty-six to forty-eight hours, the nitrile is distilled over with steam, and is obtained in a yield of about forty per cent. The oxy-nitrile remains in the distilling flask. Dihydrofencholenonitrile boils at 98° to 104° (23 mm.), has the sp. gr. 0.8951 at 16.5°, n^ = 1.44743 at 17.5°, M = 45.15, and [a] Z) =-[-25° at 19° (10 cm. tube). It is insoluble in water and is saponified only with difficulty. When boiled vigor- ously for eight hours with thirty per cent, alcoholic potash, it is changed into a small quantity of the corresponding acid and a large proportion of the amide. On distilling off the alcohol, the amide is found in the residue and is purified by recrystallization from dilute alcohol. Dihydrofencholenamide, C 9 H 17 • CONH 2 , is formed as above men- tioned by hydrolysis of the nitrile. It is crystallized from dilute alcohol and then from ethyl acetate ; it melts at 130.5°, and sub- limes slowly at 107°. Dihydrofencholenic acid, C 9 H 17 -COOH, is obtained by the hy- drolysis of the amide with concentrated hydrochloric acid ; it boils at 145° to 146°(13mm.),sp.gr. = 0.9816 at 15°, [a] D = + 4.3° at 15.5° (10 cm. tube). It forms silver and ammonium salts, of which the latter may be reconverted into the amide. Oxydihydrofencholenonitrile, C 9 H 17 0-CN, is produced in a yield of about thirty-five per cent, by the action of air on fenchimine. It is non- volatile with steam, boils at 153° to 154° (23 mm.) and is insoluble in water. Sp. gr. is 0.9792 at 15°, n^, = 1.46464 at 18°, if = 47.11, and [a) D =- 8° at 18° (10 cm. tube). Oxydihydrofencholenamide, C 9 H 17 O CONH 2 , is obtained by hy- drolysis of the oxy-nitrile with thirty per cent, alcoholic potash ; it is recrystallized from ethyl acetate and melts at 78°. It is readily soluble in boiling water, ethyl and methyl alcohol and boiling ether, sparingly in cold water. 168 THE TERPENES. Dihydrofencholenic acid lactam, C 10 H 17 ON, is formed, together with an oil which has not yet been investigated, by gently warm- ing a solution of oxydihydrofencholenamide in dilute hydrochloric acid. It separates from the filtered solution on cooling in bril- liant crystals, which melt at 136° to 137° ; it is soluble in hot alcohol and may be recrystallized from this solvent. It is not attacked by permanganate ; when heated above its melting point, it distills without decomposition. It is identical with Wallach's /2-isofenchonoxime (m. p. 137°), which is prepared by dissolving a-fencholenamide(m. p. 113° to 114°) in hot, dilute sulphuric acid and precipitating the filtered solution with alkali. ^Oxydihydrofencholenic acid, 0 9 H 17 O ■ COOH, is obtained, to- gether with the oxy-amide, by the hydrolysis of the oxy-nitrile with alcoholic potash ; a small quantity of the lactone of this acid is also formed at the same time. This acid crystallizes from hot water or ethyl acetate in splendid, hard crystals, which melt at 113° to 114°. It is a monobasic acid, is soluble in boiling water, readily soluble in alcohol, ether and ethyl acetate, spar- ingly soluble in ligroine ; it forms silver and copper salts. #-Oxydihydrofencholenic acid lactone, C 10 H 16 O 2 , is readily pro- duced by warming the oxy-acid with dilute sulphuric acid; it separates from ethyl acetate in splendid, well formed crystals, which melt at 72° and boil at 130° to 150° (10 mm.). It is very volatile with steam, somewhat soluble in boiling water and insoluble in sodium carbonate. It is dissolved by long continued boiling with caustic alkalis. Fenchocarboxylic Acids, 1 C 10 H 16 (OH) . COOH. When carbon dioxide is passed through a solution of fenchone in ether to which sodium has been added, a mixture of different compounds is obtained ; in order to separate them, the crude prod- uct is distilled under 15 mm. pressure. The fraction boiling at 150° to 180° solidifies in the receiver, and consists of the two isomeric fenchocarboxylic acids, carbofenchonone, C n H lfi 0 2 , an- hydrofenchocarboxylic acid, C n H 16 0 2 , and a pinacone, C^H^O,,, or a difenchone, C 20 H 32 O 2 . This mixture is treated with sodium hydroxide or ammonia, shaken with ether, and the aqueous liquor is acidified ; a-fenchocarboxylic acid crystallizes from this liquid more rapidly than the /9-acid. The /?-acid is also more soluble in petroleum ether than the «-acid, and a final separation may be made by means of this solvent. Wallach, Ann. Chem., 28k, 324; 300, 294; Chem. Centr., 1899 (II.), 1052; Nach. k. Ges. Wiss., Göttingen, 1899, No. 2; Ann. Chem., 315, 273. CARBOFENCHONONE. 169 a-Fenchocarboxylic acid, C u H 18 0 3 , crystallizes from acetic acid, melts at 141° to 142°, and boils without decomposition at 175° at 11 mm. pressure. It is optically active, having a specific rotatory power, [a]^ = + 11.28°, in a 4.5 per cent, ethereal solu- tion ; by mixing equal weights of the active acids prepared from d- and 1-fenchone, an inactive acid is obtained, which melts at 91° to 92°. It forms lead and silver salts. /9-Fenchocarboxylic acid, C n H 18 0 3 , melts at 76° to 77°, is dextrorotatory, and is less stable than the a-acid ; it forms fen- chyl alcohol and anhydrofenchocarboxylic acid by heating at ordinary pressure, and it is partially converted into the a-acid by distillation in vacuum. It is changed into fenchone by the action of sodium hypobromite or by an acid solution of perman- ganate. It forms lead and silver salts similar to those of the a- acid. This acid is also formed by warming carbofenchonone with an excess of a dilute solution of sodium hydroxide on the water-bath. Wallach regards a- and /9-fenchocarboxylic acids as trans- and cis-modifi cations. Anhydrofenchocarboxylic acid, C u H 16 0 2 , is prepared by boiling a-fenchocarboxylic acid at atmospheric pressure, or by fusing the a-acid with potash. It crystallizes from dilute acetone, melts at 175° and boils at 275° to 277° under ordinary pressure; it is difficultly soluble in water, is volatile with steam, and forms a lead salt. Carbofenchonone, 1 C n H 16 0 2 , results by the distillation of lead a-fenchocarboxylate in vacuum ; it separates from petroleum ether in yellow crystals, has a slight odor resembling that of camphor, melts at 96°, and boils at 273° to 274° under atmospheric pres- sure. It dissolves in warm caustic soda, being converted into /?-fenchocarboxylic acid. It yields a monoxime, C n H 16 0 . NOH, which crystallizes from methyl alcohol in needles, melting at 108°; and a dioxime, C n H I6 (NOH) 2 , which is soluble in water, and melts at 198° to 199°. By the action of ammonia it forms a compound, C u H 17 NO, which crystallizes from alcohol and melts at 205°. ^ "Carbofenchonone is an ortho-diketone. 1 By the action of zinc dust and acetic acid it is converted into an alcohol, C u H 18 0 2 , which crystallizes from dilute alcohol and melts at 89°. When the diketone is oxidized, it yields a dicarboxylic acid, C u H 18 0 4 , which melts at 172° to 173°. A lactone, C 10 H lß O 2 , is produced by the oxidation of a-fencho- carboxylic acid with potassium permanganate ; it crystallizes from dilute methyl alcohol, melts at 64.5°, and boils at 150° under 14 mm. pressure. ^Wallach, Ann. Chem., 315, 273. 170 THE TEKPENES. A pinacone, 1 C 20 H 34 O 2 , or a difenchone, C 20 H 32 O 2 , is the neutral crystalline compound formed as a by-product during the prepara- tion of the fenchocarboxylic acids from fenchone; it melts at 122°. It yields no well defined derivatives, and decomposes, when heated under reduced pressure at temperatures below 100°, into fenchone and a non-crystalline product. As a result of his extended investigations on fenchone and its derivatives, Wallach suggests the following formula as the most probable representation of the constitution of fenchone : ;H 2 CH CH— CH, j H 3 C-C-CH 3 CH, OH CC Fenclione. 10. FENCHYL ALCOHOL, C 10 H 17 OH. Fenchyl alcohol is formed by the reduction of fenchone in an alcoholic solution with sodium (Wallach 2 ). Thirty grams of fenchone are dissolved in 135 to 140 grams of alcohol in a capacious flask, and eighteen grams of sodium are gradually added. When the evolution of hydrogen slackens, the flask is warmed on a water-bath, and the solution of the last par- ticles of sodium may eventually be accelerated by the cautious addition of a small quantity of water. When all of the sodium is consumed, enough water is added to dissolve the sodium alco- holate which tends to separate ; two layers are thus formed, the one an aqueous solution of sodium hydroxide, the other a lighter, alcoholic solution which contains fenchyl alcohol. The sodium hydroxide solution is removed, and the fenchyl alcohol separated by shaking the alcoholic solution with water ; at first it forms an oil, which solidifies when agitated with ice-water. It is then pressed on a porous plate, fused, dried with potassium hydroxide, and rectified. Larger quantities of fenchyl alcohol may also be prepared in one operation by this method. According to Bouchardat and Tardy, 3 the benzoyl esters of fen- chyl alcohol and isoborneol are formed by heating the dextroro- tatory terpene (pinene 4 ), obtained from eucalyptus oil of Eucalyptus Wallach, Ann. Chem., 315, 273. 2 Wallach, Ann. Chem., 263, 143; see also Gardner and Cockburn, Journ. Chem. Soc, 73, 276. 3 Bouchardat and Tardy, Compt. rend., 120, 1417. ^Compare with Wallach and Gildemeister, Ann. Chem., 246, 283. PENCHYL FORMATE. 171 globulus, with benzoic acid. By the action of certain acids (sul- phuric, benzoic) on French (levorotatory) turpentine, Bouchardat and Lafont 1 obtained a mixture of dextrorotatory and inactive fenchyl alcohols, which they at first designated as " isocamphenol " and " synthetical isoborneol " ; on oxidation these two alcohols yield levorotatory and inactive fenchone, respectively. Fenchyl alcohol forms a colorless, crystalline mass, having^ a penetrating and extremely disagreeable odor ; it is readily volatile with steam, and is freely soluble in alcohol, ether, petroleum ether, and ethyl acetate, but is insoluble in water. It has the specific gravity 0.933 at 50°, boils at 201°, and, as usually pre- pared, melts at 40° to 42° ; pure fenchyl alcohol, however, formed as a by-product in the preparation of the fenchocarboxylic acids 2 or obtained by the hydrolysis of fenchyl hydrogen phthalate, 3 melts at 45°. Fenchyl alcohol prepared from dextrorotatory fenchone is levorotatory; 4 its specific rotatory power *is (XU = — 10.35° (Wallach), and [ Goldschmidt and Kisser, Ber., 20, 489. 2 Wallach, Ber., 28, 32. 3 Wallach and Schräder, Ann. Chem., 279, 379. * Wallach, Ann. Chem., 305, 223; compare Harries and Kaiser, Ber., 31, 1807. f-DICARVELONES. 195 a-Dicarvelone crystallizes in splendid, rhombic crystals, and the two active modifications melt at 148° to 149°. D-a-l-Dicarvelone, prepared from dextro-carvone, is levorotatory, [a] D == — 73.92°, and L-a-d-dicarvelone from levo-carvone is dextrorotatory, [a] D = 4-73.28°. A racemic, inactive a-dicarvelone is obtained by crystallizing together molecular quantities of D-a-1- and L-a-d- dicarvelone ; it separates from alcohol in rhombic crystals, and melts at 120° to 121°. That a-dicarvelone is a diketone, is proved by the formation of the phenylhydrazone, C 20 H 30 (N 2 HC 6 H 5 ) 2 ; the hydrazones of the active modifications melt and decompose at 215°, and the inactive hydrazone decomposes at about 200°. a-Dicarvelonoxime, C 20 H 30 (NOH) 2 , is prepared according to the method of preparation of carvoxime. The active modifications melt at 223°, and the inactive derivative melts^ and decomposes at 287°. The active acetyl derivatives of the oxime melt at 187°, and the inactive modification melts at 166°. a-Dicarvelone dihydrobromide, C 20 H 30 O 2 -2HBr.— a-Dicarvelone contains two ethylene linkages, and unites with two molecules of hydrogen bromide. The D-a-l-dicarvelone dihydrobromide sepa- rates from alcohol in white crystals, and melts at 165°. /9-Dicarvelones, C 20 H 30 O 2 .— When a-dicarvelone dihydrobromide is heated with an equivalent amount of alcoholic potash, hydro- bromic acid is eliminated, and a compound isomeric with a- dicarvelone is obtained; this substance is termed ß-dicarvelone. D-a-l-Dicarvelone dihydrobromide yields a dextrorotatory ^-modi- fication, [a]^ + 79.18°, and L-a-d-dicarvelone gives rise to L-/9-l-dicarvelone, \a\ D = - 82.66° ; both active modifica- tions crystallize well, and melt at 207°. By the union of D-/9-d- and L-/9-l-dicarvelone, an inactive derivative is produced, which melts at 168°. The /3-dicarvelones form phenylhydrazones, and also combine with two molecules of hydrogen bromide, form- ing dihydrobromides, which are identical with the bromides pre- pared from the a-dicarvelones. r -Dicarvelones, C 20 H 30 O 2 .— These compounds are prepared by adding the a- or /3-dicarvelones, in small portions at a time, to well cooled, concentrated sulphuric acid ; after standing for a short time, the product is poured onto ice, the resulting precipitate is filtered, dried, and crystallized from alcohol. D-f-l-Dicarvelone, prepared from D-a-1- or D-/3-d-dicarvelone, is levorotatory, r«]^ = - 213.4° and 201.8°, respectively; L-f-d-di carve - lone is dextrorotatory, \_a] D = + 236.8°. Both active modi- fications melt at 126°, and the inactive ^-derivative melts at 112°. 196 THE TEEPENES. The f-dicarvelones differ from the corresponding a- and ß- compounds in that they do not form phenylhydrazones. Dieucarvelone, C 20 H 30 O 2 . — When hydrochloro- or hydrobromo- carvone is treated with zinc and potassium hydroxide in a manner similar to that described in the reduction of carvone, a number of crystalline products result, amoug which the compound, C 20 H 30 O 2 , dieucarvelone, melting at 172°, has been isolated and studied; the same compound is likewise produced in the reduction of eu- carvone, C 10 H u O, with sodium hydroxide and zinc. Dieucarvelone melts at 172°, yields a phenylhydrazone and an oxime, but does not form a solid addition-product with hydro- bromic acid. A compound, C 20 H 30 O 2 , isomeric with dieucarvelone, is also formed in the reduction of eucarvone ; it melts at 128°. A com- pound, melting at 110° to 112°, is likewise produced in the same reaction ; it may possibly prove to be identical with inactive y- dicarvelone, melting at 112°. The behavior of carvone towards potassium permanganate has been studied by Best, 1 and by Wallach, 2 but only the most im- portant results of these investigations will be briefly mentioned here. When carvone is treated with aqueous potassium permanganate, it yields oxyterpenylic acid, C 8 H 12 O ß , melting at 192.5° ; when this acid is distilled under diminished pressure, it loses water and yields a neutral compound, C 8 H 10 O 4 (dilactone), melting at 129°. According to Best, oxyterpenylic acid is reduced by hydriodic acid to terpenylic acid, melting at 55° to 56°. According to Schryver, 3 terpenylic acid has the constitution of a lactone of diaterpenylic acid : (CH 3 ) 2 C O (CH 3 ) 2 COH HOCO — CHj — CH — CH 2 — CO HOCO— CH 2 — CH— CH 2 — COOH Terpenylic acid. Diaterpenylic acid. According to Wallach, another acid isomeric with oxyterpenylic acid is formed, together with the latter, by the action of perman- ganate on carvone; this acid melts at 94° to 95°. (Compare with Tiemann and Semmler. 4 ) iO. Best, Ber., 27, 1218 and 3333. 2 Wallach, Ann. Chem., 275, 155; Ber., 27, 1496. a Schryver, Journ. Chem. Soc, 68, 1327; Mahla and Tiemann, Ber., 29, 928. 'Tiemann and Semmler, Ber., 28, 2141. CARVEOL METHYL ETHER. 197 The values for the specific rotatory powers of dextro- and levo- carvone and their derivatives are given in the following table. Prepared from Compounds of the Carvone Series. Dextro-car- vone or levo- limonene [a]^ Levo-carvone or dextro- limonene [a] D _ Observer. Carvone, + 62.00° —62.00° A. Beyer, Arch. Pharm., 221, 283. Carvone hydrogen sul- phide, + 5.53° — 5.55° A. Beyer, Arch. Pharm., 221, 283. Carvoxime, +39.71° —39.34° Wallach and Conrady, Ann. Chem., 252, 148. Benzoyl carvoxime, +26.47° —26.97° Wallach and Conrady, Ann. Chem., 252, 148. Benzoyl hydrochlorocar- voxime, —10.58° + 9.92° Macheleidt, Ann. Chem., 270, 179. 2. CARVEOL METHYL ETHER, C 10 H 15 OCH 3 . When carvone, C 10 H 14 O, is reduced in an alcoholic solution with sodium, dihydrocarveol, C 10 H 17 OH, is formed. An alcohol, C 10 H 15 OH, corresponding to carvone is not at present known, although the methyl ether of carveol, C 10 H 15 OCH 3 , has been ob- tained. When one hundred grams of limonene tetrabromide are warmed on the water-bath with a solution of fifteen grams of sodium in two hundred cc. of methyl alcohol for eight hours, a compound is produced which has the constitution, C 10 H 14 BrOCH 3 ; it is volatile with steam, boils at 137° to 140° under 14 mm. pressure, has the specific gravity of 1.251 and the coefficient of refraction, n^ = 1.51963, at 18° (Wallach 1 ). If a solution of forty-two grams of this compound, C 10 H 14 BrO- CH 3 , in two hundred cc. of ethyl alcohol be treated with thirty-six grams of sodium, the bromine atom is replaced by hydrogen and carveol methyl ether results. The reaction-product is distilled in a current of steam, and the ether, being volatile, is separated from the distillate by the addition of water ; it is dried with potassium hydroxide and rectified. Carveol methyl ether boils at 208° to 209°, and has a specific gravity of 0.9065 at 18° ; the refractive index is n^ = 1.47586 at 18°, from which a molecular refraction is calculated that indicates the presence of two double linkages in the molecule. The ether iWallach, Ann. Chem., 281, 129. 198 THE TERPENES. is optically active, and unites with halogens and halogen hydrides forming additive products. It yields inactive carvone by oxida- tion with chromic anhydride in glacial acetic acid solution. Optically inactive carveol methyl ether may be obtained from crystalline terpineol (Wallach 1 ). If terpineol dibromide be treated with hydrogen bromide, it yields a tribromide, which was formerly designated as 1, 2, 4-, more recently as 1, 2, 8-tribromoterpane. When this tribromide is submitted to the action of sodium methylate, the bromine atom, 2, is replaced by a methoxyl-group, while the bromine atoms, 1 and 8, are eliminated as hydrogen bromide : CHBr H,C CH, H S C CH 8 H 3 C CH, Terpineol (solid). Terpineol dibromide. 1, 2, 8-Tribromoterpane. Carveol methyl ether. Carvone. 3. EUCARVONE, C 10 H u O. According to Baeyer, 2 a ketone isomeric with carvone is ob- tained, when hydrobromocarvone, prepared by the action of hydrogen bromide on carvone, is treated with alcoholic potash ; the purification of the hydrobromocarvone is not necessary. After saturating carvone dissolved in glacial acetic acid with hy- drobromic acid, the solution is poured into water; the oil which Wallach, Ann. Chem., 281, 140. «Baeyer, Ber., 27, 812; compare also Wallach, Ann. Chem., S05, 237. EUCARVOXIME. 199 separates is washed with water, extracted with ether, and, after agitating the ethereal solution with sodium bicarbonate, it is care- fully dried with anhydrous sodium sulphate. This solution is then well cooled with ice and treated with methyl alcoholic potash (one part of potassium hydroxide in two parts of methyl alcohol) until a separation of potassium bromide is no longer noticeable. The mixture is then poured without delay into cold, dilute sul- phuric acid ; the ethereal solution is separated, washed with bi- carbonate of sodium, the ether allowed to evaporate, and the resulting oil distilled with steam. Eucarvone prepared in this manner boils at 210° to 215° under ordinary pressure; it is better, however, to distill in vacuum, since the ketone is partially decomposed into carvacrol by distillation under atmospheric pres- sure. . It has an odor differing from that of carvone, but similar to that of peppermint and of menthone ; it is optically inactive, boils at 104° to 105° (25 mm.) without decomposition, and has a specific gravity of 0.948 at 20°. Its boiling point and specific gravity are, therefore, lower than those of carvone. It is quanti- tatively converted into carvacrol by heating at its boiling point for an hour. Eucarvone derives its name from the production of a pure, deep blue color on boiling a small quantity of the substance in a test-tube with about two cc. of concentrated methyl alcoholic pot- ash ; the color is very unstable and disappears at once on the ad- dition of water. It does not combine with acid sodium sulphite ; it differs from carvone in that it reacts very slowly with Phenylhydrazine, form- ing an oily phenylhydrazone (Baeyer). Eucarvoxime, C 10 H 14 NOH, results by treating an alcoholic solu- tion of eucarvone with the theoretical quantities of hydroxyl- amine hydrochloride and sodium bicarbonate. After standing for one week, the reaction-product is poured onto ice, and eucar- voxime separates at once in very small crystals. It is obtained in the form of leaflets by dissolving in alcohol and diluting the solution with water. It melts at 106°. According to Wallach, 1 the oxime is more readily prepared as follows. Fifty grams of eucarvone are dissolved in 750 cc. of ninety per cent, alcohol and to this is added a solution of fifty grams of hydroxylamine hydrochloride in fifty cc. of hot water. A concentrated solution of fifty grams of sodium hydroxide is then slowly added, and the, liquid is warmed in a flask with re- flux condenser on the water-bath, for about one hour. After cool- i Wallach, Ann. Chem., S05, 239. 200 THE TERPENES. ing, the reaction-product is poured into ice water and acidified with some acetic acid. The oxime separates at once ; it is pressed on a porous plate, and recrystallized from four times its quantity of methyl alcohol. It melts at 106°. It is very stable towards dilute sulphuric acid, and when it is boiled with this acid for half an hour, only traces of regenerated eucarvone can be detected by means of methyl alcoholic potash It is more readily decomposed into eucarvone by dilute sulphuric acid if substances are present which combine easily with hy- droxylamine, for example methyl isonitrosoacetone. It dissolves in concentrated sulphuric acid without development of heat and without change. Beckmann's chromic acid mixture colors crys- tals of carvoxime black ; crystals of eucarvoxime are not af- fected. Eucarvone semicarbazone, 1 C 10 H 14 = N NH-CO NH 2 , crystal- lizes in concentric aggregates of prisms, and melts at 183° to 185°. Condensation-products of eucarvone and benzaldehyde. 2 — Benzyli- dene eucarvone, C 6 H.CH = C 10 H 12 O, is the chief product obtained in the condensation of eucarvone and benzaldehyde in alcoholic solution by means of sodium ethylate. It crystallizes from al- cohol in well defined, slightly yellowish prisms, melting at 112° to 113°; it is the normal condensation-product of these two compounds. A second product is also formed ; it has the com- position, C 24 H p , and seems to be formed by the elimination of one molecule of water from one molecule of eucarvone and two molecules of benzaldehyde. It crystallizes from a mix- ture of chloroform and alcohol in white leaflets, and melts at 193° to 194°. Dieucarvelone, 3 C 20 H 30 O 2 , is formed in the reduction of eucarvone with sodium hydroxide and zinc; it melts at 172°. (See under carvone.) Eucarvone yields dihydroeucarveol, C 10 H 17 OH, when it is re- duced in alcoholic solution with sodium. 1 Unsymmetrical or #em 4 -dimethyl succinic acid is formed, to- gether with a considerable quantity of acetic acid, by the oxida- tion of eucarvone with a permanganate solution (Baeyer 5 ). An alcohol, C 10 H 15 OH, corresponding to eucarvone is not known. 1 Baeyer, Ber., 27, 1922. nVallach, Ber., 29, 1600; Ann. Chem., 805, 242. s Wallach, Ann. Chem., 805, 242. * Baeyer, Ber., 81, 2067. 5 Baeyer, Ber., 29, 3. PINOCARVOXIME. 201 4. PINOCARVONE, C 10 H u O. This ketone was formerly called "isocarvone" owing to its sup- posed similarity to carvone. More recent investigations, however, have shown that it possesses no similarity with the compounds of the carvone series, and, accordingly, Wallach 1 has changed its name to pinocarvone. The corresponding alcohol, C 10 H 15 OH, was called " isocarveol" but is now designated as pinocarveol. When pinylamine nitrate is heated with a solution of sodium nitrite, an alcohol, C 10 H 15 OH (pinocarveol), is produced ; the latter yields pinocarvone by oxidation with chromic acid (Wallach 2 )^ A solution often grams of pinocarveol in forty grams of glacial acetic acid is very gradually treated with a solution of ten grams of chromic anhydride in a mixture of five cc. of water and ten cc. of glacial acetic acid. A very vigorous reaction takes place at once, and, on its completion, the product is distilled with steam ; the resultant crude ketone is converted into the oxime, and the latter is purified by steam distillation. Pure pinocarvone is ob- tained by boiling the oxime with dilute sulphuric acid. Pinocarvone is a liquid having a characteristic odor, which differs from that of carvone, but when warm resembles that of peppermint. It boils at 222° to 224°, and at 19° has the specific gravity 0.989 j its refractive index at 19° is 1.506, corresponding to a molecular refraction of 45.42, which indicates the presence of two double linkages in the molecule. Since this supposition re- specting the constitution of pinocarvone has not yet been proved by chemical methods, and more especially since a transformation of pinocarvone into carvacrol has not been accomplished, it is possible that pinocarvone and pinocarveol are not to be regarded as deriva- tives of dihydrocymene. It combines with acid sodium sulphite forming a crystalline compound, which is decomposed by water. It produces a deep red color when treated with acids. When pinocarvone is dissolved in alcoholic ammonia and satu- rated with hydrogen sulphide, pinooarvone hydrogen sulphide is precipitated as a white, amorphous substance ; it is readily soluble in chloroform, sparingly in alcohol, and is slowly decomposed by boiling with caustic soda. Pinocarvoxime, C 10 H 14 NOH, is prepared by the action of hy- droxylamine on crude pinocarvone and is purified by distillation with steam. It separates from alcohol or ether in well defined crystals, and melts at 98°. 1 Wallach, Ann. Chem., S00, 286. 2 Wallach, Ann. Chem., 277, 150; 279, 387. 202 THE TERPENES. Pinocarvone semicarbazone, 1 C 10 H 14 = N NH CO NH 2 , is spar- ingly soluble, and does not crystallize well. It separates from aqueous methyl alcohol in slightly yellowish crystals, and melts at 204°. 5. PINOCARVEOL, C 10 H 15 OH. ^ Pinylamine, C 10 H 15 NH 2 , obtained by the reduction of nitroso- pinene, may be converted into a secondary alcohol, C 10 H 15 OH, which is called pinocarveol because of its relation to pinocarvone. Pinocarveol is prepared according to the following method (Wallach 2 ). Twenty grams of pinylamine nitrate are heated with a solu- tion of ten grams of sodium nitrite in 100 cc. of water for some time. A yellow oil separates, and is distilled in a current of steam ; the distillate is shaken with an oxalic acid solution in order to remove basic compounds, and is again distilled with steam. The alcohol so obtained is dried over potassium hydrox- ide, and boils at 215° to 218°. It has a turpentine-like odor, and a specific gravity of 0.978 at 22°; its refractive power is 1.49787 at 22°, corresponding to the molecular refraction of 45.55. 6. PINENOL, C 10 H 15 OH. According to Genvresse, 3 a terpene alcohol, C 10 H 15 OH, is formed by passing nitrous acid fumes into well cooled pinene ; the prod- uct is distilled with steam, and the resulting oil is fractionally distilled under reduced pressure. Pinenol is a slightly yellow colored liquid, and possesses an agreeable odor ; it is insoluble in water, but readily soluble in the usual organic solvents. It boils at 143° under 38 mm. pressure, and at 225° under 740 mm.; it is partially decomposed by distilla- tion at atmospheric pressure. It has the specific gravity 0.9952 at 0°, and the refractive index, n^ = 1.497, from which the molec- ular refraction 44.563 is calculated ; the theoretical molecular re- fraction is 44.85, if the presence of one double linkage in the mole- cule be assumed. Its specific rotatory power is [a\ D = — 14.66°. It unites with one molecule of bromine, forming an additive compound. It is converted into cymene on treatment with phos- phoric oxide. Pinenol acetate, C 10 H 16 O-COCH 3 , has an odor recalling that of lavender, and boils at 150° under 40 mm. pressure. 'Wallach, Ann. Chem., 300, 286. z Wallach, Ann. Chem., 277, 149; 300, 286. 3 P. Genvresse, Compt. rend., 180, 918. LIMONENOL. 203 7. PINENONE, C 10 H u O. Pinenone 1 is the ketone corresponding to pinenol, C 10 H 16 OH, and results from the oxidation of the latter with a chromic acid ^ifisa yellow liquid, has an agreeable odor, and boils at 132° (42 mm.) ; it has a specific gravity 0.9953 at 0°, and is levo- rotatory, [a]^ - 21.12°. Its refractive index is n^= 1.5002, giving the molecular refraction 44.33 ; the calculated value for the molecular refraction is M = 43.84, if it be assumed that the molecule contains one double linkage. The ketone is unsaturated, and adds one molecule of bromine. Pinenonoxime, C 10 H H :NOH, is produced by heating pinenone with an alcoholic solution of hydroxylamine. It is also formed in small quantity during the preparation of pinenol from pinene. It crystallizes in rhombic crystals, melting at 89 ; it boils with partial decomposition at under a pressure of 40 mm. It is levorotatory, [a] D = — 22.3°. The dibromide, C 10 H 14 (NOH) Br 2 , melts at 152°. The phenyl carbimide, C 10 H U -NO CO NHC 6 H 5 , crystallizes in needles and melts at 135°. The benzoyl and butyryl derivatives melt at 1U5 and 74°, respectively. Pinenone semicarbazone, C 10 H 14 =N-NH CO • NH 2 , melts at 82° 8. LIMONENOL, C 10 H 15 OH. This alcohol 2 is produced by the action of nitrous fumes on dextro-limonene cooled by a freezing mixture of ice and salt; the reaction-product is neutralized with sodium carbonate, distilled with steam, and the alcohol is then separated from unaltered limonene by extraction with a concentrated solution ot sodium salicylate, this solvent having the property of dissolving terpene alcohols, but not terpenes. Limonenol is a colorless liquid having an agreeable odor, aitter- ine from that of pinenol or limonene. It boils at 135° under a pressure of 15 mm., has a sp. gr. 0.9669 at 18° a refractive index, ^=1.497, and a rotatory power, [«^= + 19 21 at li . Its molecular refraction is 45.99, which corresponds with the cal- culated value of a compound containing two double Unkings. It absorbs two molecules of bromine without evolution of hydrogen bromide. On oxidation with chromic acid it yields the ketone, limonenone, C 10 H 14 O. iP. Genvresse, Compt. rend., ISO, 918. 2P. Genvresse, Compt. rend., 182, 414. 204 THE TERPENES. 9. LIMONENONE, C in H,£>. 1U 14 Limonenone 1 is the ketone corresponding to the alcohol, limo- nenol, and is prepared by oxidizing this alcohol with a chromic acid mixture. It is a colorless liquid, having an agreeable odor. At 20° it has the sp. gr. 0.9606, the refractive index, n^ = 1.487, and the specific rotatory power [a\ D = + 16° 4'. Its molecule contains two double linkings. Limonenonoxime, C 10 H 14 NOH, is formed by treating the ketone with alcoholic solutions of hydroxylamine hydrochloride and potassium hydroxide; it is purified by steam distillation. It melts at 85.5° ; but after the fused material has solidified, it then melts at 72°. It is formed in small quantity by the action of nitrous fumes on limonene. This compound is perhaps identical with levo-carvoxime, since the melting point of the latter corresponds with the lower melting point (72°) of limonenonoxime ; the two compounds have the same specific rotatory power, \a\ D = -39° 42', and their benzoyl derivatives (m. p. 95°), and phenylcarbimides (m. p. 133°) agree in properties. 10. SABINOL, C 10 H 15 OH. The chemists of Schimmel & Co. 2 observed that the princi- pal constituent of the oil of savin is an alcohol, sabinol, which occurs partly free and partly combined as an acetic acid ester. It is obtained by the fractional distillation of the saponified oil of savin, and boils at 210° to 213°, or at 105° to 107° under 20 mm. pressure. It was at first assumed that sabinol had the composition, ^ioH 17 OH, but more recent investigations of Fromm 3 and Semmler 4 indicate that its formula is C 10 H 15 OH. The fraction of oil of savin boiling at 195° to 235°, when further fractionated, yields an oil boiling at 222° to 224°, and consisting largely of the acetate of sabinol. When this acetate is hydrolyzed with alcoholic potash, sabinol is obtained. The alcohol is more readily obtained by boiling the crude oil of savin with alcoholic potash for half an hour, and distilling the product with steam; the oil which passes over is purified by repeated fractionation. The yield is about fifty per cent, of the crude oil. *P. Genvresse, Compt. rend., 132, 414. «Schimmel & Co., Semi-Annual Report, Oct., 1895, 44. 3 E. Fromm, Ber., 81, 2025. C are obtained in the same reaction with bisnitrosopule- gone. The diisonitroso-derivative decomposes at 190° ; its for- mation depends on the elimination of the C 3 H 6 -group from the pulegone molecule. Its diacetate melts at 125° to 130°. The diisonitroso-derivative yields the anhydride of triisonitroso-methyl- cyclohexanone, C 7 H 9 N 3 0 2 , by the action of hydroxylamine ; it melts at 128° to 129°, and yields an acetate, melting at 139° to 140°. Benzylidene pulegone, 3 C 10 H 14 O = CH • C 6 H,, is formed by the condensation of pulegone and benzaldehyde with sodium ethylate ; baeyer and Henrich, Ber., 28, 652. 2 Baeyer and Prentice, Ber., 29, 1078. s Wallach, Ber., 29, 1595; Ann. Chem., 305, 267. OXIDATION OF PULEGONE. 243 it boils at 202° to 203° under a pressure of 12 mm. On reduc- tion with sodium and alcohol, it yields benzylpulegol, C 10 H 16 (OH)- CH 2 C 6 H 5 . Pulegenacetone, 1 C 13 H 20 O, is formed by warming a mixture of pulegone, ethyl acetoacetate, and glacial acetic acid with fused zinc chloride, for ten hours, on the water-bath. It boils at 148° to 153° under a pressure of 8 mm., solidifies in the receiver, and crystallizes from light petroleum in prisms, which melt at 72° to 73°. Its oxime is crystalline, melts at 134° to 135°, and yields a benzoyl derivative, which crystallizes in yellow needles, and melts at 178° to 179°. 3-Chloro-J 2(4:8) -terpadiene, 2 C 10 H 15 C1, is produced by the action of phosphorus pentachloride on pulegone ; it is a colorless oil, boils at 101° (25 mm.), has a sp. gr. 0.983 at 19°, and n^ = 1.49928. With an excess of bromine, it yields a tetrabromide, C 10 H n ClBr 4 . Formic acid converts the chloroterpadiene into methyl cyclohex- anone. Bispulegone, 3 C 20 H 34 O 2 , results by the action of aluminium amalgam on pulegone ; it crystallizes in needles, melts at 118° to 119°, and is readily soluble in benzene, ether and acetic acid. When pulegone is reduced with sodium amalgam in an acetic acid solution, menthone and menthol are also formed. Oxidation of pulegone. — Pulegone yields acetone and optically dextrorotatory ß-methyl adipio acid, C 7 H 12 0 4 (m. p. 84.5°), on oxidation with potassium permanganate. ß-Methyl adipic acid is converted into a lactonic acid, CyH^O^, by oxidation ; when the calcium salt of /?-methyl adipic acid is distilled with soda-lime, it yields a ketone, C 6 H 10 O, ß-methyl ketopentamethylene. According to Semmler, 4 these reactions indi- cate that /9-methyl adipic acid has the following constitution : HOOC— CH 2 — CH 2 — CH(CH 3 )— CH 2 — COOH /3-Methyl adipic acid. CO-CH — CH 2 — C( CH 3 )— CH 2 — COOH H 3 C-CH— CH^ I .0 CH 2 — CH 2 7-Valerolactone-y-acetic acid. ß -Methyl ketopentamethylene. 1 Barbier, Compt. rend., 127, 870. «Klages, Ber., 82, 2564. sHarries and Boeder, Ber., 32, 3357. * Semmler, Ber., 25, 3515; 26, 774. 244 THE TERPENES. Semmler derives the following constitutional formula of pule- gone from these transformations : ? ? H 3 H 2 C QH, H 2 C CO Y H 3 C CH S Pulegone. This formula has further been proved by Wallach. 1 He showed that when pulegone is boiled with anhydrous formic acid, or is heated with water in an autoclave at 250°, a hydrolytic de- composition takes place with the production of acetone and methyl cyclohexanone (boiling point 169°): H 3 C CH S Pulegone. Methyl cyclohexanone. Acetone. The formyl derivative of cycloheptylenamine (hexahydro- meta-toluidine), C 7 H 13 NH 2 , is formed in an analogous manner, when pulegone is boiled with ammonium formate. Methyl cyclohexanone, 1 C 7 H 12 0, is obtained from pulegone as above mentioned. It is also formed during the action of concen- trated sulphuric acid on pulegone, 2 by boiling pulegone hydro- bromide with alcohol and lead hydroxide, by boiling pulegone with alcohol and basic lead acetate, or when it is distilled with quinoline. 3 It boils at 169°, has the specific gravity 0.915 at 21°, and the refractive index, n^, = 1.4456, at the same temperature; M = i Wallach, Ann. Chem., 289, 337. 2 Harries and Roeder, Ber., 32, 3357. »Zelinsky, Ber., 30, 1532. METHYL PULEGEN" ATE . 245 32.59. Its oxime melts at 43° to 44°, and the semicarbazone at 180°. When methyl hexanone is reduced with sodium and alco- hol, methyl cyclohexanol (meta-oxyhexahydrotoluene), C 7 H 13 OH, is formed; it boils at 175° to 176°. For the numerous derivatives of methyl cyclohexanone, refer- ence must be made to the original publications. 1 PULEGENIC ACID, C 10 H 16 O 2 . Pulegone forms a liquid dibromide, which yields pulegenic acid when it is heated with a solution of sodium methylate : C 10 H 16 OBr 2 + H 2 0= 2HBr + C 10 H 16 O 2 . This acid boils without decomposition at 150° to 155° under a pressure of 13 mm.; when distilled at atmospheric pressure, it decomposes into carbonic anhydride and a hydrocarbon, C 9 H 16 . This hydrocarbon boils at 138° to 140°, has the sp. gr. 0.790 and refractive index, n^ = 1.44, at 20°; it yields a nitrosochloride, melting at 74° to 75° (Wallach 2 ). The amide of pulegenic acid crystallizes in woolly needles, and melts at 121° to 122°. When it is treated with phosphoric an- hydride, it is converted into the nitrite, which boils at 218° to 220°, has the sp. gr. 0.8935 and index of refraction, 11^ = 1.47047, at 22°. The preparation of pulegenic acid from pulegone is accom- plished by a break in the ring structure ; its formation resembles, in certain respects, that of campholenic acid from camphor and of fencholenic acid from fenchone. Pulegenic acid is an unsaturated compound ; when its solution in methyl alcohol is saturated with hydrochloric acid gas, the hydrochloride of pulegenic methyl ester is formed. It boils at 113° to 116° (13 mm.), and solidifies at a low temperature. Methyl pulegenate, 3 C 10 H 16 O 2 CH 3 , boils at 89° to 90° (10 mm.), and is formed by the action of a methyl alcoholic solution of sodium methylate upon the hydrochloride. On acidifying the alkaline solution which remains after the removal of the methyl •Wallach, Ann. Chem., 289, 337; 309, 1; 312, 171} 314, 147; Ber., 29, 1595; 29, 2955; Klages, Ber., 32, 2564; Harries and Roeder, Ber., 32, 3357; methyl hexanone prepared from ß -methyl pimelinic acid, see Einhorn and Ehret, Ann. Chem., 295, 181 ; Kondakoff and Schindehneiser, Journ. pr. Chem., 1900 [II], 61, 477; J. von Braun, Ann. Chem., 314, 168; Harries, Ber., 34, 300; Bouveault and Tetry, Bull. Soc. Chim., 1901 [III], 25, 441. 2 Wallach, Ann. Chem., 289, 337. 'Wallach, Ann. Chem., 300, 259. 246 THE TERPENES. alcohol and ethereal salt by distillation with steam, the lactone, C 10 H 16 O 2 , is precipitated; it boils at 125° to 127° (15 mm.). The acid, C 10 H 16 O 2 , produced together with the lactone, boils at 145° to 147° (15 mm.) and at 256° to 260° at 760 mm.; sp. gr. = 0.9955, n^ =1.47547, at 21°. It closely resembles, but is not identical with, pulegenic acid ; its amide crystallizes from methyl alcohol in needles, and melts at 152°. A brominated lactone is formed by treating pulegenic acid with potassium hypobromite ; by the action of alcoholic sodium methylate, it yields pulegenolide, C 10 H 14 O 2 , which melts at 44° to 45°, and boils at 265° to 268°. An oxy-acid, C 10 H 16 O 3 , is pro- duced on hydrolyzing the lactone with aqueous alkali ; it melts at 95°, and forms a silver salt. An oxy-lactone, C 10 H 16 O 3 , is formed by oxidizing pulegenic acid with a cold solution of potassium permanganate ; it melts at 129° to 130°. This compound is also obtained by the action of moist silver oxide on the brominated lactone above mentioned. The oxy-lactone is converted into pulegenolide by the action of phosphorus pentachloride, and subsequent treatment of the product with sodium methylate. The ketone, C 9 H ie O, is produced when the oxy-lactone, C 10 H 16 O 3 , is treated with moderately dilute sulphuric acid, carbon dioxide being eliminated ; it is a saturated compound, boils at 183°, has the specific gravity 0.8925 and refractive power, n^ = 1.44506, at 21°. Its oxime melts at 94°. When pulegone dibromide is heated, it loses hydrogen bromide and yields methyl cyclohexanone and m-cresol. Synthetical (Ortho-iso- (?)) Pulegone, C 10 H 16 O. When methyl cyclohexanone, C 7 H 12 0, and acetone are con- densed by means of alcoholic sodium methylate, a ketone, 1 C 10 - H 16 0, is obtained, which closely resembles natural pulegone, and is isomeric, but not identical, with it. If natural pulegone be termed £>ara-pulegone, then the structure of this synthetical ketone will be either that of pseudo- or or£Ao-iso-pulegone. Wallach is inclined to regard it as an ortho-iso-pulegone, but the investiga- tions are not yet complete. Synthetical pulegone is purified by conversion into the semi- carbazone ; when regenerated from this compound, it boils at 94° to 95° under 14 mm. pressure, or at 214° to 215° at atmospheric pressure. It has the specific gravity 0.918 and the refractive i Wallach, Ber., 29, 1595 and 2955; Ann. Chem., S00, 268. ISOPULEGOL AND ISOPULEGONE. 247 index, n^ = 1.46732, at 20°. Its odor is scarcely distinguishable from that of natural pulegone, but its chemical properties are widely different. It is strongly dextrorotatory. It yields a semicarbazone, which exists in two modifications, the one melting at 70° to 85°, and the second at 144° ; both modi- fications yield the same synthetical pulegone on treatment with dilute acids. Synthetical pulegone is not converted into methyl hexanone and acetone by the action of formic or dilute sulphuric acid. The benzylidene derivative of synthetical pulegone, C 10 H 14 O = CH C 6 H 5 , melts at 83° to 84°. A compound, C 13 H 20 O, is also formed during the condensation of methyl hexanone and benzaldehyde ; it boils at 179° to 183° under reduced pressure. Synthetical pulegol, C 10 H 17 OH, is produced by reducing synthet- ical pulegone in ethereal or alcoholic solution with sodium. It is a viscous liquid, has an odor of terpineol, and boils at 103° to 104° (15 mm.), and at 215° under atmospheric pressure. Its specific gravity at 20° is 0.912 and refractive power, n^ = 1.4792. When treated with phosphoric anhydride, it yields a terpene, C 10 H 16 , boiling at 173° to 175°. Wallach 1 suggests the following formula for synthetical pulegone: 12. ISOPULEGOL, C 10 H 17 OH, and ISOPULEGONE, C 10 H 16 O. An alcohol, C 10 H 17 OH, corresponding with natural pulegone, has not yet been obtained free from menthol by the reduction of pulegone. An alcohol, C 10 H 17 OH, isopulegol, is, however, produced from citronellal, C 10 H 16 O, an aliphatic terpene alde- hyde. It results in the form of its acetate by heating citronellal with an equal weight of acetic anhydride in an autoclave at 180° to CH 2 Ortho-isopulegone. i Wallach, Ann. Chem., S00, 276. 248 THE TERPENES. 200°, for ten or twelve hours ; or by heating citronellal with an- hydrous sodium acetate for fifteen to twenty hours at 150° to 160° (Tiemann and Schmidt 1 ). According to Barbier, 2 when citronellal is agitated with ten parts of five per cent, sulphuric acid for twelve hours, isopulegol is formed, together with menthoglycol, C 10 H 18 (OH) 2 ; the latter compound is also obtained from isopulegol. According to Tiemann, 3 commercial citronellal contains some isopulegol, together with other compounds ; its presence in the mixture may be recognized by its conversion into isopulegone upon oxidation. Properties. — Isopulegol has an odor like menthol, boils at 91° under a pressure of 13 mm., and has the rotatory power, [a] D = — 2.65°. Its specific gravity is 0.9154 at 17.5°, the re- fractive index, n^ = 1.47292, and the molecular refraction, M = 47.20. Menthoglycol 2 (menthandiol-3, 8), C 10 H 18 (OH) 2 , is a compound closely related to isopulegol. It is formed, together with some isopulegol and a compound, C 20 H 34 O (b. p. 185° at 10 mm.), by agitating citronellal with ten parts of five per cent, sulphuric acid for twelve hours. It crystallizes from petroleum ether in white plates, melting at 81° to 81.5°. Acetic anhydride at 100° con- verts it into a monoacetate (b. p. 137° to 138° at 10 mm.), while at 150°, in the presence of fused sodium acetate, the acetyl derivative of isopulegol results. Hydrogen chloride in pres- ence of glacial acetic acid changes the glycol into a mixture of two isomerides, C 10 H 18 C1 O COCH 3 , boiling at 124° to 125° (10 mm.). This glycol may also be obtained directly from isopulegol. Isopulegone, C 10 H 16 O, is formed by the oxidation of isopulegol with an acetic acid solution of chromic anhydride ; 4 the product seems to consist of a mixture of two stereo-isomeric modifications, which are designated as a- and /9-isopulegone. 5 According to Tiemann, the mixture of a- and /3-isopulegone, obtained by the oxidation of isopulegol, boils at 90° (12 mm.), has the specific gravity 0.9213, the index of refraction, rijy = 1 .4690, the molecular refraction, M = 45.98, and the specific rotatory power, [a]^= -f- 10° 15', in a one decimeter tube. On treating with boiling dilute sulphuric acid and alcohol or with Niemann and Schmidt, Ber., 29, 903. 2 Barbier and Leser, Compt. rend., 12k, 1308. »Tiemann, Ber., 32, 825. 4 Tiemann and Schmidt, Ber., 29, 903; 30,22; Tiemann, Ber., 82, 825. 5 Harries and Boeder, Ber., 82, 3357. /5-ISOPULEGONE SEMICARBAZONB. 249 formic acid, methyl cyclohexanone is obtained which is identical in every respect with the compound produced from natural pulegone. Isopulegone differs widely from natural and synthetical pulegones in its chemical behavior. It does not combine with acid sodium sulphite. When reduced with sodium and alcohol, it yields iso- pulegol, no menthol being produced ; menthol is not formed by the action of sodium and alcohol on isopulegol. a-Isopulegone 2 is also obtained in a yield of seventy per cent, by heating natural pulegone with methyl alcohol and basic lead nitrate on the water-bath for half an hour ; it is separated from unchanged pulegone by treating its ethereal solution with aluminium amalgam, distilling with steam and converting into its oxime (m. p. 120° to 121°). When regenerated from the latter compound, a-isopulegone is obtained as a colorless oil, which boils at 98° to 100° (13 mm.), has a specific gravity 0.9192 at 19.5°, and a specific rotatory power, \a\ D = — 7° 8'; when allowed to stand in contact with dilute sulphuric acid for some time it is rendered inactive. It is converted into dextrorotatory, natural pulegone when its alcoholic solution is left in contact with baryta water for twenty-four hours (Harries and Roeder). a-Isopulegonoxime, C 10 H 16 NOH, is formed, together with the ß- derivative, by the action of hydroxylamine on isopulegone. It melts at 120° to 121°, and is volatile with steam. /9-Isopulegonoxime, C 10 H 16 NOH, is prepared with the a-modifi- cation ; it melts at 143° (Harries and Roeder). According to Tiemann, isopulegone yields two oximes, one melting at 120° to 121° (a-isopulegonoxime), the other melting at 134° ; the latter is non-volatile with steam and may possibly be a mixture of the a- and /9-oximes. a-Isopulegone semicarbazone, C 1() H 16 = NNHCONH 2 , crystal- lizes from dilute alcohol in needles, and melts and decomposes at 173° to 174° (Harries). According to Tiemann, it melts at 171° to 172°, and is readily soluble in ether. /9-Isopulegone semicarbazone, C 10 H 16 = N • NH • CO ■ NH 2 , melts at 183° (Harries). According to Tiemann, it melts at 180°, and is sparingly soluble in ether. A mixture of the a- and /?-semicarbazones melts at 173° to 174°. It is obtained by treating the isopulegone, resulting from the oxidation of isopulegol, with semicarbazide solution ; it is separable into the a- and ^-derivatives, having the above-de- scribed properties (Tiemann). When a-isopulegonoxime (m. p. 121°) or the a-semicarbazone (m. p. 173° to 174°) is acted upon by boiling dilute sulphuric acid and alcohol, it yields methyl cyclohexanone. 250 THE TERPENES. According to Tiemann and Harries, isopulegone is represented by the formula The following table may serve to illustrate some of the points of difference between natural pulegone, isopulegone and synthet- ical or ortho-isopulegone. Natural Pulegone. Isopulegone. Synthetical Pulegone. Boiling point, 99°tol01°(12mm.) 90° (12 mm.). 94° to 95° (14mm.). Acid sodium sul- phite, forms a crystalline derivative. does not yield a derivative. Heated with formic acid, yields methyl cy- clohexanone. yields methyl cy- clohexanone. does not yield methyl cyclohex anone. Reduction with alcohol and so- dium, yields pulegol (?) containing men- thol - f b. p. 108° to 110° (14 mm.). yields isopulegol, b.p. 91° (13 mm.) yields synthetical pulegol, b. p. 103° to 104° (15 mm.). Oximes, normal oxime, Ci 0 - H 16 NOH, m. p. 118° to 119°. pulegone hydroxy- lamine, C 10 H 19 - N0 2 , m. p. 157°. a-derivative, C 10 H 16 - NOH,m. p. 121°. /3-derivati ve, C 10 H 16 - NOH, m. p. 143°. mixture (?), m. p. 134°. liquid, b. p. 145° (15 mm. ). Semicarbazones, m. p. 172°. a-derivative, m. p. 171° tol72°. ß -derivative, m. p. 180° ■ mixture (a- and /?-), m. p. 173° to 174°. exists in two modifi- cations ; m. p. 70° to 85°, and 144°. 13. MENTHENONE, C 10 H 16 O. A ketone, C 10 H 16 O, was obtained by Urban and Kremers 1 by boiling nitrosomenthene (m. p. 65° to 67°) with dilute hydro- chloric acid (1 : 1), and in the year 1899 Wallach 2 gave it the name menthenone. 1 Urban and Kremers, Amer. Chem. Journ., 16, 401. 2 Wallach, Ann. Chem., 305, 272. ISOCAMPHOE. 251 Menthenone boils at 205° to 208°, and has the specific gravity of 0.916 at 20°; the ketone prepared from the optically active and inactive nitrosomenthenes is optically active. It has a de- cided odor of peppermint (Richtmann and Kremers 1 ). According to Wallach, menthenone boils at 95° to 97° under 12 mm. pressure, has the refractive index, n^= 1.4733, at 20°, the molecular refraction, M = 46.42, and the specific gravity 0.919 at 20°. Menthenone hydrogen sulphide, 1 C 10 H 16 O • 2H 2 S, is readily formed by passing hydrogen sulphide into a solution of the ketone in al- cohol, and subsequently adding concentrated ammonia. It forms crystals, melting at 212° to 215°, and is soluble in chloroform and hot methyl alcohol. Nitrosomenthenone, C 10 H 15 O NO, is prepared according to Baeyer's method for the preparation of bisnitrosopulegone ; it melts at 115° to 115.5°. Menthenone phenylhydrazone, C I0 H 16 = N NHC 6 H 5 , crystallizes with considerable decomposition from warm alcohol, and melts at 73.5° to 74° (Richtmann and Kremers). Menthenone is reverted into nitrosomenthene by the action of hydroxylamine (Urban and Kremers). When menthenone is reduced with sodium and ether, according to Beckmann's method, it yields an oil (possibly a new alcohol, C 10 H 17 OH, or unchanged menthenone), and a solid compound (a pinacone (?)) ; the latter substance crystallizes from hot methyl alcohol, and melts at 160° to 162° (Richtmann and Kremers). Dibenzylidene menthenone, C 10 H 12 O ( = CH-C 6 H 6 ) 2 , results by the condensation of menthenone and benzaldehyde ; it crystallizes from hot alcohol in light yellow needles, and melts at 129° to 130°. When reduced with zinc dust and glacial acetic acid it gives rise to the corresponding alcohol, C 24 H 26 0, which forms colorless crystals, and melts at 72° to 75° (Wallach). 14. ISOCAMPHOE, C 10 H 16 O. When camphoroxime, in glacial acetic acid solution, is treated with nitrous acid (sodium nitrite), it yields a compound, C 10 H 16 N 2 O 2 , which Angeli and Rimini 2 call pernitrosocamphor and which Tiemann 3 terms camphenylnitr amine ; it melts at 43°. Pernitrosocamphor is attacked by cold concentrated sulphuric acid with evolution of nitric oxide and formation of a ketone, iRichtmann and Kremers, Amer. Cbem. Journ., 18, 771. 2Angeli and Rimini, Ber., 28, 1077 and 1127; Gazz. Chim., 26 [IT], 29, 34, 45, 228, 502 and 517; 28 [I], 11. sTiemann, Ber., 28, 1079; 29, 2807. 252 THE TERPENES. C 10 H 16 O, isocamphor. This ketone should possibly be classified with the ketodihydrocymenes. Isocamphor is also formed by treating isopernitrosofenchone, C 10 H 16 N 2 O 2 , with concentrated sulphuric acid. Isocamphor 1 is an oil having a pleasant odor, boils with slight resinification at 214° to 216° under ordinary pressure, and slowly changes in the air j it immediately reduces permanganate solution, and behaves as an unsaturated compound. It combines with bromine and hydrogen bromide forming additive products, and seems to differ from dihydrocarvone and dihydroeucarvone. It is resinified by alkalis ; it does not condense with benzaldehyde or ethyl formate. The pure ketone is obtained by treating its oxime with dilute sulphuric acid. Isocamphoroxime, 1 C 10 H 16 NOH, melts at 106°. It is dissolved unaltered by concentrated sulphuric acid, but is converted into isocamphor by boiling with dilute sulphuric acid. Isocamphor semicarbazone, C 10 H 16 = N-NH • CO • NH„, melts at 215°. Isocamphor bisnitrosochloride, (C 10 H 16 O) 2 (NOCl) 2 , is produced by the action of acetyl chloride on a mixture of isocamphor and amyl nitrite, cooled with ice ; it forms small, white crystals, and melts with decomposition at 120° to 121°. Tetrahydroisocamphor, 1 C 10 H 19 OH, is formed by the reduction of isocamphor with sodium and alcohol ; it is a heavy, colorless oil, having a lavender-like odor. It is an alcohol and yields a phen- ylurethane, which forms colorless crystals and melts at 155°. Dihydroisocamphor,C 10 H 18 O, is formed by oxidizing the preceding compound with chromic acid ; it is a colorless oil, boiling at 203°. Its semicarbazone crystallizes in thin, white needles, melting at 162° ; dilute sulphuric acid reconverts it into dihydroisocamphor. Dihydroisocamphor is stable towards permanganate, and yields a crystalline acid sodium sulphite derivative. On mixing dihydroisocamphor with one molecule of benzal- dehyde and gradually adding an alcoholic solution of sodium ethylate (one molecule), benzylidene dihydroisocamphor, 2 C 10 H 14 O = CH-C 6 H 5 , is formed ; it crystallizes from alcohol in small, white needles, melting at 217°. The formation of this compound indi- cates that dihydroisocamphor contains the group — CO — CH 2 — . When isocamphor is oxidized with an alkaline solution of potassium permanganate, it yields a-isopropyl glutaric acid, C 8 H 14 0 4 , which crystallizes in white needles and melts at 96° ; it has been synthetically prepared by W. H. Perkin. 3 It forms an Compare M. Spica, Gaz. Chim. Ital., SI [II], 286. 2 Rimini, Gazzetta (1900), 80, 596. 3 W. H. Perkin, jun., Journ. Chem. Soc, 69, 1495. J 6 -MENTHENE-2-ONE. 253 anhydride, C 8 H 12 0 3 , which crystallizes in long needles, and melts at 60°. It is converted into succinic acid by oxidation with chromic acid, and also gives rise to an anilide, melting at 160°. It may further be mentioned that a ketone, 1 C 10 H 16 O, isomeric with camphor, is formed by the dry distillation of 3-methyl-6-iso- propyl-d 2 -cyclohexenone carboxylic acid, C 10 H 15 OCOOH ; it is an oil, having a camphor-like odor, and boils at 217° to 219°. Its oxime forms beautiful, monoclinic crystals. /9-Isocamphor, C 10 H 15 OH, is an unsaturated alcohol which Duden 2 obtained by the action of nitrous acid on eamphenamine, C 10 H 15 NH 2 ; it sublimes in long needles having the odor and appearance of camphor, and melts at 102°. It has the specific rotatory power, [«] = -f 17.65°, in methyl alcohol. Its phenyl- urethane crystallizes from petroleum in long needles and melts at 112°. 15. PINOLONE, C 10 H 16 O, and PINOLOL, C 10 H 17 OH. Wallach 3 obtained the ketone, pinolone, by treating isopinole dibromide, C 10 H 16 OBr 2 , with zinc dust and glacial acetic acid, and also by the reduction of pinole tribromide. It has an odor recall- ing that of amyl acetate ; it boils at 214° to 217°, has a specific gravity 0.916 and refractive index, n^ = 1.46603, at 20°. Pinolonoxime, C 10 H 16 NOH, boils at 150° under a pressure of 15 mm.; on reduction it yields a base, the carbamide of which crystallizes from methyl alcohol and melts at 186°. Pinolone semicarbazone, C 10 H 16 = N NH-CO-NH 2 , melts at 158°. Pinolol, C 10 H 17 OH, is the alcohol obtained by reducing pinolone with sodium and alcohol. It possesses a linalool-like odor, boils at 108° under 15 mm., has a specific gravity 0.913 and an index of refraction, n^ = 1.47292, at 20°. 16. J 6 -MENTHENE-2 -ONE , CLK.O. ' lu Id According to Harries, 4 when hydrobromocarvone is reduced in methyl alcoholic solution with zinc dust, about one-quarter of the product consists of carvone and the remainder is a ketone, C 10 H 16 O, called J 6 -menthene-2-one. It is a yellow colored oil, boils at 227° to 228°, or at 96° to 97° under 9 mm. pressure; it has a sp. gr. 0.9411 at 10° and 0.9351 at 19°, and a specific rotatory power, [a]^^ + 49.5°, in a 10 cm. tube. 1 J. A. Callenbach, Ber., SO, 639. 2 Duden and Macintyro, Ann. Chem., 313, 59. 3 Wallach, Ann. Chem., 306, 275; 281, 154; Ber., 28, 2710. * Harries, Ber., 34, 1924. 254 THE TERPENES. Its semicarbazone crystallizes in plates and melts at 173° to 174°; its oxime crystallizes in large prisms and melts at 75° to 77°. The hydrogen sulphide derivative, 2C 10 H 16 O • H 2 S, crystallizes in lustrous needles and melts at 222° to 225°. The oxaminoxime, C 10 H 16 (NOH)(NH 2 OH), crystallizes with one- half molecule of water in needles, and melts at 95° to 97° ; it forms an oxalate, melting at 130°to 135°. When it is oxidized byacurrent of air, it gives rise to a dioxime, C 10 H 16 (NOH) 2 , which crystallizes in colorless prisms and melts with decomposition at 194° to 196°. When J 6 -menthene-2-one is reduced with zinc dust and alco- holic sodium hydroxide, it yields dextro-carvomenthone. When re- duced with aluminium amalgam, it gives a dimolecular compound, C 20 H 34 O 2 ; the latter yields a phenylhydrazone, melting at 260°. The ketone unites slowly with hydrobromic acid, forming a yellow oil. 17. TERPINEOL, C 10 H 17 OH. The name terpineol was formerly used to designate a substance which to-day is recognized as a mixture of isomeric alcohols, C 10 H 17 OH. It will be well first to consider the preparation and properties of this mixture, which was termed " terpineol," before entering into a discussion of the individual alcohols contained in it. These alcohols occupy an intermediate position between di- pentene and terpine : c ioH 16 ~ j C 10 H 17 OH ~ ^ C 10 H 18 (OH), Dipentene. Terpineol. Terpine. Therefore, those terpenes which can be converted into terpine may also be transformed into " terpineol " by the addition of one molecule of water, while " terpineol " may also be obtained by the elimination of water from terpine hydrate. Deville 1 probably obtained " terpineol " as a by-product in the preparation of terpine hydrate from turpentine oil. According to Flawitzky, 2 " terpineol " is prepared when one part of levoro- tatory turpentine oil is mixed with one-half part of sulphuric acid and one and one-half parts of ninety per cent, alcohol, the mixture being allowed to stand for twelve hours. Tilden 3 first obtained " terpineol " from terpine hydrate, and Wallach 4 more closely defined the conditions under which ' ( ter- pineol " could be most conveniently prepared from this com- pound. He found that dilute phosphoric acid gave relatively 1 Deville, Ann. Chem., 71, 351. 2 Flawitzky, Ber., 12, 2354. s Tilden, Journ. Chem. Soc., ^878, 247; 1879, 287; Ber., 12, 848; Jahresb. Chem., 1878, 1132. < Wallach, Ann. Chem., 230 , 247 and 264. TERPINEOL. 255 small quantities of terpenes, and a large yield of " terpineol." In order to prepare it, twenty-five grams of terpine hydrate are boiled with fifty cc. of a twenty per cent, solution of phos- phoric acid in a reflux apparatus, for fifteen minutes ; the product is distilled in a current of steam, and the resultant oil submitted to a fractional distillation, the " terpineol " being contained in the fraction boiling at 215° to 218° (Wallach). ||The French chemists Bouchardat and Voiry 1 prepared " ter- pineol " by the action of very dilute sulphuric acid (1 to 1000) on terpine hydrate ; they showed that five-sixths of the resulting " terpineol " solidified at — 50° to crystals, melting at 30° to 32°. This product is designated as 1 ' solid terpineol." It is certain that solid terpineol is also contained in Wallach's " terpineol," 2 although for some time it was impossible to isolate the solid compound from the liquid product. If terpine be given the formula : it will be seen that three isomeric, unsaturated alcohols, C 10 H 17 OH, may be derived from it, thus : HoC CEL. COH H 3 C CH ; Terpine. ■3) la. Ha. III. A'-Terpen^-ol. A*-Terpen-l-ol. H3C CH 3 A*W-Terpen-l-ol. 1 Bouchardat and Voiry, Compt. rend., 10k, 996; Ber., 20, 286. 2 Tiemann and R. Schmidt, Ber., 28, 1781; Semi- Annual Report of Schim- mel & Co., April and May, 1901, 75. 256 THE TERPENES. By totally different methods, Wallach and Baeyer came to the same conclusion, that solid terpineol (m. p. 35°) should be considered as a J 1 -terpen-4-ol, expressed by formula la. This formula, however, is hardly conformable to the results of experi- ments which have more recently been published by Wallach, 1 and by Tiemann and Semmler ; 2 according to their researches it ap- pears possible, and even probable, that terpine should be repre- sented by the formula : H 3 C CH 3 Terpine. Of the three terpenols which may be derived from this terpine, one has the constitution represented in formula III ; the other two have the formulas : lib. C CHo .A H 3 C CH 3 A«(8>-Terpen-l-ol. Since this alcohol is readily converted into terpinolene, the above formula supports Baeyer' s formula of terpinolene and also agrees with the constitution which "Wallach ascribes to tribromo- 272 THE TERPENES. terpane (m. p. 110°). The following formulas illustrate these re- lations : GH, CH ^H 2 Hjv CH S s ^ H,C C HqC CHq HqC CHq CH I ' CBr A H,C CH A« s )-Terpen-l-ol. Terpinolene. H, C CH 2 CBr 1 CH /\ H 3 C CH 3 Dipentene dihydrobromide. CH, CH, CBr C A /\ H 2 C CH 2 H 2 C CH h,c ch, h 2 c^ ch, 6bt 5 CBr CBr H 3 C CH 3 H 3 C CHj 1, 4, 8-Tribromoterpane. Terpinolene di- (m. p. 110°). bromide. These formulas would be quite as probable if the constitution of dipentene dihydrobromide were represented by the formula : 3H, H 2 C CH 2 H 9 (j CH 2 OBr \ H,C CH, ISOMERIC TERPINEOL. 273 Trioxyhexahydrocymene, according to Baeyer's nomenclature, 1 1, 4-, 8-trioxyterpane, C 10 H 20 O 3 , is obtained, when J 4(8) -terpenol (m. p. 69° to 70°) is dissolved in ether and oxidized with a dilute potassium permanganate solution. It forms crystals containing one molecule of water, and melts at 95° to 96°.' It loses the water of crystallization when heated to 50° or 60° in a vacuum; the anhydrous substance melts at 110° to 112°. Hydrobromic acid converts it into Wallach's tribromoterpane, melting at 110° to 111 0 (Baeyer and Blau 1 ). 19. ISOMERIC TERPINEOL, C 10 H 17 OH, MELTING AT 32° TO 33°. In an investigation of liquid "terpineol," which is largely employed in perfumes, the chemists of Schimmel = 1.46534, at 21°, and a molecular refraction, M = 50.48. Tetrahydrocarvyl bromide, 2 C 10 H 19 Br, is colorless, boils at 95° to 99° (10 mm.), has a specific gravity 1.1870 at 21°, a refrac- tive index, n^, = 1.49060, at 21°/21°, and a molecular refraction, M = 53.39. The properties of carvomenthyl chloride and bromide are almost identical with those of carvomenthene hydrochloride and hydrobromide. When carvomenthyl chloride or bromide is treated with moist silver oxide, tertiary carvomenthol is formed, together with a small quantity of a compound, C 10 H 22 O 3 , which crystallizes in slender needles, and melts at 101° to 102°. "Carvanol," 3 C 10 H 20 O, a compound obtained by the reduction of " carvenol," C 10 H 16 O, is probably identical with tetrahydrocar- veol ; on oxidation " carvanol " is converted into " carvanone " (tetrahydrocarvone), C 10 H 18 O. 3. TETRAHYDROEUCARVONE, C 10 H 18 O. When dihydroeucarvoxime hydriodide, C 10 H 16 NOHHI, is re- duced with zinc dust and an alcoholic solution of hydrogen chloride at 0°, it is converted into the ketone, tetrahydroeucarvone. 4 It is freed from unsaturated compounds by treatment with potassium permanganate. The pure ketone boils at 108° to 115° under a pressure of 20 mm. It yields a liquid oxime, C 10 H ]8 NOH. Its semicarbazone, C 1() H 1S = N'NH-CO'NH 2 , crystallizes from ethyl acetate in fine needles, melts at 191°, and is sparingly soluble in ether and ethyl acetate. 1 Wallach, Ann. Chem., 277, 130. 2 Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257. 3 Marsh and Hartridge, Journ. Chem. Soc, 73, 857. «Baeyer and Villiger, Ber., 31, 2067. 294 THE TERPENES. Tetrahydroeucarvone is not acted upon by amyl nitrite and hydrochloric acid. When it is oxidized with the theoretical quantity of a cold, four per cent, potassium permanganate solution, it is partially converted into the ketonio acid, C 10 H 18 O 3 ; this acid is purified by regenera- tion from its semicarbazone. It is a liquid acid, and is probably a methyl ketone. Its semicarbazone, C 10 H 18 O 2 = N-NH-CONH 2 , is sparingly soluble, but crystallizes from warm ethyl acetate in long needles, melting at 191°. Its oxime, C 10 H 18 O 2 = NOH, crystallizes in transparent prisms, which melt at 101° to 102°. G-em- dimethyl adipic acid, C 8 H u 0 4 , is the chief product of the oxidation of tetrahydroeucarvone with cold permanganate ; it crystallizes from petroleum ether in prisms, and melts at 87° to 88°. When tetrahydroeucarvone is oxidized with a warm, fairly concentrated solution of permanganate, it gives rise to a mixture of acetic, oxalic, dimethyl malonic, and ^em-dimethyl succinic acids. 4. THUJAMENTHONE, C 10 H 18 O. On heating thujone at 280°, it is converted into carvotanace- tone ; this differs from isothujone, and yields carvomenthol (tetra- hydrocarveol) by reduction. When thujone is treated with dilute sulphuric acid, it is converted into isothujone ; on reduction, this compound forms an alcohol, C 10 H 19 OH, thujamenthol (dihydro- isothujol), which can be very readily distinguished from tetrahy- drocarveol (Wallach 1 ). Thujamenthone is obtained by oxidizing thujamenthol in glacial acetic acid solution with chromic anhydride. It is a ketone, and is purified by means of its semicarbazone. It boils at 208° to 209°, has a specific gravity of 0.891 and index of refraction, 11^= 1.44708, at 20°. It is optically inactive, and is stable towards a cold solution of potassium permanganate (Wallach). Thujamenthonoxime, C 10 H 18 NOII, crystallizes from dilute methyl alcohol in transparent prisms, and melts at 95° to 96°. Isothujamenthonoxime, C 10 H, 9 NO, is obtained by treating thuja- menthonoxime with phosphorus pentachloride ; it crystallizes from hot water in long, thin needles, melting at 113° to 114°, and is more readily soluble than the oxime, melting at 95° to 96°. Unlike isomenthonoxime, isothujamenthonoxime is very unstable, and is even reconverted into thujamenthonoxime, melting at 95° to 96°, by standing for some time with water. Thujamenthone semicarbazone, C 10 H 18 = NNHCONH 2 , melts at 179°. It is slowly reconverted into thujamenthone by boiling with dilute sulphuric acid. 1 Wallach, Ber., 28, 1955; Ann. Chem., 286, 104. MENTHONE. 295 Oxidation of thujamenthone. 1 — When thujamenthone is carefully oxidized with potassium permanganate, it yields the ketonic acid, C 10 H 18 O 3 , which boils at 273 °, being converted into the keto-lac- tone, C 10 H 16 O 3 . The semicarbazone of the ketonic acid melts at 174.5°. A solution of sodium hypobromite changes the ketonic acid into a dibasic acid, C 9 H 16 0 4 , melting at 134.5°. The keto-lactone, C 10 H 16 O 3 , is produced on oxidizing thujamen- thone with chromic acid; it melts at 41°, and yields an oxime, melting at 156° (Wallach). According to Semmler, the above-mentioned ketonic acid boils at 273°, being converted into the preceding keto-lactone, C 10 H 16 O 3 , melting at 43° ; the oxime melts at 155°. On oxidation, the keto-lactone gives rise to ß-isopropyl laevulinic acid. 5. THUJAMENTHOL, C 10 H 19 OH. Thujamenthol or dihydroisothujol is obtained by reducing isothujone with sodium and alcohol. 2 It is a viscous liquid, hav- ing an odor resembling that of terpineol. It boils at 211° to 213°, has a sp. gr. of 0.895 and a refractive index, np = 1.46345, at 22°. It yields thujamenthone by oxidation with chromic acid (Wallach 2 ). 6. MENTHONE, C 10 H 18 O. Menthone has the constitutional formula : — H,C CH, CO H 8 C CHj It occurs, together with menthol, esters of menthol, menthene and limonene, in peppermint oil. 3 According to Power and Kleber, 3 the amount of menthone in American oil of peppermint reaches 12.3 per cent. Andres and Andrejew 4 found it in Rus- sian peppermint oil. The separation of pure menthone from peppermint oil by frac- tional distillation is impossible, since menthone boils but a few i Wallach, Ber., 30, 423; Semmler, Ber., 33, 275. 2Wallach, Ber., 28, 1955. 3 Schimmel & Co., Semi- Annual Report, April, 1895, 56. * Andres and Andrejew, Ber., 24, 560, Ref.; Ber., 25, 609. 296 THE TERPENES. degrees lower than menthol, and cannot, therefore, be separated from the latter compound. It is prepared, however, by oxidation of menthol. In this manner optically inactive menthone was first prepared by Moriya, 1 who heated menthol with potassium Chro- mate and sulphuric acid in a sealed tube at 120° for ten hours. Later, Atkinson and Yoshida 2 succeeded in the preparation of strongly dextrorotatory menthone by repeated treatments of men- thol with a chromic acid mixture at 135°; they assumed, therefore, that the product obtained by Moriya contained levo-menthone as an impurity, and that for this reason alone it appeared optically inactive. The comprehensive experiments of Beckmann 3 have led to a very simple method for the preparation of menthone, and have further shown that its optical behavior is quite unusual. Men- thone is very readily inverted by acids, as will be shown later more in detail. Levo-menthone results by the oxidation of levo-menthol if the action of an excess of acid be avoided as much as possible. Beck- mann has suggested the following method. To a solution of sixty grams (one molecule) of potassium dichroraate and fifty grams (two and one-half molecules) of concentrated sulphuric" acid in 300 grams of water, which is warmed to about 30°, forty-five grams of crystallized menthol are added in one portion ; the sur- face of the mixture immediately assumes a deep black color, due to the formation of a chromium compound. If the mixture be now vigorously shaken, the liquid takes on a dark color, and becomes warm ; the menthol at first softens, and is then completely converted into a black, crystalline chromium compound. The oily men- thone is not formed until the temperature rises above 53°, which is generally accomplished, without heating, in about thirty min- utes ; at this point the chromium compound is suddenly decom- posed into a brown mass with separation of liquid menthone. If large quantities of menthol are employed, care must be taken to cool the mixture so that the temperature does not rise above 55°. The menthone forms a dark, oily layer on the cold reaction- product ; it is taken up in ether, and agitated successively with water and dilute sodium hydroxide in order to remove the chro- mium compounds. For further purification, portions of ten to twenty grams of menthone are rapidly distilled with steam, the oil is separated, dried over anhydrous sodium sulphate, and rectified. i Moriya, Journ. Chem. Soc, 1881, 77; Jahresb. Chem., 1881, 629. 2 Atkinson and Yoshida, Journ. Chem. Soc, 1882, 50; Jahresb. Chem., 1882, 775. 3 Beckmann, Ann. Chem., 250, 322; 289, 362. DEXTROROTATORY MENTHONE. 297 Levorotatory menthone, prepared in this way, is a mobile liquid ; it does not solidify when placed in a freezing mixture, has a soft, peppermint-like odor, and differs from menthol in its bitter and sharp taste. It boils at 207°, and has the specific gravity 0.896 at 20°. Menthone, regenerated from its semicarbazone, boils at 208°, has a sp. gr. 0.894 and refractive index, n^ = 1.4496 (Wallach J ). The following specific rotatory powers were obtained for five quantities of menthone prepared at different times, and in each case the menthone contained no menthol : [a] ^ = - 24.78°, - 25.51°, - 26.98°, - 27.12°, - 28.18°. The menthone was prepared by oxidizing menthol according to the above-described method ; the menthol melted at 43°, and had a specific rotatory power, [«] jD = — 50.59°, in a ten per cent, alcoholic solution, and — 49.35° in a twenty per cent, solution. Dextrorotatory menthone is produced by the action of acids on levo-menthone. A mixture of ten parts of concentrated sul- phuric acid and one part of water is allowed to stand for some time in a freezing mixture ; two parts of levo-menthone are then added and the mixture is gently shaken until the menthone dis- solves in the slowly melting acid, forming a yellow liquid. When solution is complete, the temperature is gradually raised to 30° and the reaction-product poured onto ice. The resulting dextro- menthone is immediately extracted with ether and the ethereal solution washed with soda ; the menthone is distilled rapidly with steam and dried with fused sodium sulphate (Beckmann). If pure levo-menthone, free from menthol, be employed, the resultant dextro-menthone does not differ from the levo-modifica- tion in odor, boiling point, etc. Various preparations showed the specific rotatory powers: [«]i>= + 26.33°, + 26.67°, etc., to + 28.14°. An inactive product is produced by mixing equal quantities of dextro- and levo-menthone, having rotatory powers of the same degree but of opposite direction ; this product, however, must be regarded as a mixture, since, if it be converted into the oxime, pure levo menthonoxime may be isolated. When levorotatory menthone is treated with dilute sulphuric acid, its levorotatory power diminishes until it reaches zero, and then becomes dextrorotatory to about + 8° ; this change in the rotatory power is dependent on the temperature, time of action and concentration of the acid. If dextrorotatory menthone be treated in the same manner, its dextrorotatory power also di- i Wallach, Ber., 28, 1955. 298 THE TERPENES. minishes, and finally reaches a value of about +8°, which seems to correspond to a condition of equilibrium. The two modifica- tions of menthone suffer similar transformations by the action of dry hydrogen chloride, acetic acid, hot sodium hydroxide solu- tion, cold sodium alcoholate or boiling water. The rotatory powers of the menthones slowly change on standing at the ordi- nary temperature. Respecting the large number of similar obser- vations of Beckmann, reference must be made to his original pub- lications. Menthone does not combine with acid sodium sulphite. It is converted into menthol by reduction in a moist ethereal solution with sodium. 1 When levo-menthone is heated with ammonium formate at 190° to 200°, according to Leuckart's method, the product consists chiefly of dextrorotatory menthylamine, C 10 H 19 - NH 2 , together with some of the levorotatory isomeride. 2 Levo- menthylamine is also formed by reducing levo-menthonoxime. When menthone is added in small portions to a cold mixture of phosphorus pentachloride and ligroine, hydrochloric acid is given off, and a monoehloride, C 10 H 17 C1, and a dichloride, C 10 H lg Cl 2 , are obtained. The monoehloride boils at 205° to 208°, has the specific gravity at 0° of 0.9833, and is dextrorotatory ; it does not lose hydrogen chloride even when boiled with quinoline. The dichloride boils at 150° to 155° under 60 mm. pressure, and has the specific gravity of 1.0824 at 0° (Berkenheim 3 ). According to Jünger and Klages, 4 chlorotetrahydrocymene, C 10 H 17 C1, is obtained by the action of phosphoric chloride on menthone ; by successive treatment with bromine and quinoline it is converted into chlorodihydrocymene, C 10 H 15 C1, which boils at 210° to 212° under atmospheric pressure. When chlorodihydro- cymene is further treated with bromine, and the product is dis- tilled with quinoline, 3-chlorocymene is produced : i Beckmann, German patent, No. 42,458; Ber., 21, 321, Ref.; Ber., 22, 912. 2 Wallach, Ber., 24, 3992; 25, 3313; Wallach and Küthe, Ann. Chem., 276, C 3 H 7 3-Chlorocymene. 296. 3 Berkenheim, Ber., 25, 693. * Jünger and Klages, Ber., 29, 314. /9-METHYL ADIPIC ACID. 299 Dibromomenthone, 1 C 10 H 16 Br 2 O, is produced by adding two molec- ular proportions of bromine to I- or d-nienthone dissolved in chlo- roform. It separates from alcohol in colorless crystals, melts at 79° to 80°, and is dextrorotatory. It is reconverted into men- thone by the action of glacial acetic acid and zinc dust. With hydroxylamine, it yields the oxime, C 10 H 16 Br(OH) = NOH, which melts at 136° to 137°. When the dibromo-compound is heated with boiling quinoline, thymol is formed. By the action of an excess of bromine on menthone, a crystal- line tetrabromo-m-cresol is obtained, together with a compound, 2 C 10 H 8 OBr 6 ; the latter melts and decomposes at 148° to 149°. /9-Methyl adipic acid, C 7 H 12 0 4 , is formed by the oxidation of menthone with potassium permanganate (Manasse and Rupe 3 ); it is also obtained, together with the so-called oxymenthylic acid, C 10 H 18 O 3 , by oxidation of menthol with potassium permanganate or chromic acid, and, according to Semmler, it is one of the prod- ucts formed in the oxidation of pulegone. The acid is optically active. Manasse and Rupe explain the formation of /3-methyl adipic acid from menthone by means of the following formulas : H 3 C CH 3 Menthone. CH 3 H 2 C CH a H 2 C COOH COOH /?-Methyl adipic acid. H,C :ooh H 3 C CHj( Oxymenthylic acid, the interme- diate ketonic acid. 'Beckmann and Eichelberg, Ber., 29, 418. "Baeyer and Seuffert, Ber., 3%, 40. sManasse and Rupe, Ber., 27, 1820. 300 THE TEKPENES. Oxymenthylic acid is also formed by oxidizing menthone with chromic acid. 1 When menthone is oxidized with Caro's reagent (potassium persulphate and concentrated sulphuric acid), it forms the corre- sponding t-lactone, 2 C 10 H lg O 2 ; it crystallizes from methyl alcohol, and melts at 46° to 48°. It yields an oxy-acid (m. p. 65° to 66°), and a ketonic acid, whose oxime melts at 100° to 102°. Levo-menthonoxime, C 10 H 18 NOH, is prepared by the following method (Beckmann 3 ). Twenty parts (one molecule) of menthone are dissolved in two and one-half times its amount of ninety per cent, alcohol, and treated with twelve parts (1.3 molecules) of hy- droxylamine hydrochloride and a little more than the theoretical quantity of acid sodium carbonate. The reaction takes place in the cold in less than one day, but if the mixture be warmed it is complete in a few minutes. On the addition of water, the oxime separates as an oil which soon solidifies ; it is pressed on a plate, recrystallized from dilute alcohol, and melts at 59°. According to Wallach, 4 it boils at 250° to 251°. If the levo-menthone used in the preparation of the oxime contains menthol, or is partially inverted, liquid products are formed which prevent the immediate separation of the solid oxime ; when these oily compounds are cooled, levo-menthonoxime sepa- rates in crystals. Beckmann found the specific rotatory powers of levo-menthon- oxime obtained at different times, as : [a\ D = - 40.75°, - 41.97°, - 42.51°. Levo-menthonoxime dissolves in dilute acids and alkalis and may be recovered from these solutions by means of ether. Men- thone is formed by allowing the oxime to remain in contact with dilute sulphuric acid for some time, or by boiling its sulphuric acid solution ; the rotatory power of this regenerated menthone is, of course, less than that of the ketone from which the oxime was prepared, since a portion of the menthone is inverted by the action of the acid. Concentrated sdlphuric acid at 100° converts it into an isomeric compound, melting at 68° to 83°. The hydrochloric acid salt of levo-menthonoxime is precipitated by passing dry hydrogen chloride into an ethereal solution of the oxime ; it crystallizes from alcohol in small tablets, which melt at 118° to 119°, and have the specific rotatory power, [«]2)= — 61.16°. This salt is converted into the levo-oxime by the action of sodium hydroxide. 'Beckmann and Mehrländer, Ann. Chem., 289, 367. 2 Baeyer and Villiger, Ber., 32, 3625. 3 Beckmann, Ann. Chem., 250, 329. «Wallach, Ann. Chem., 277, 157. ISO-LEVO-MENTHONOXIME. 301 Dextro-menthonoxime, C 10 H 18 NOH, is prepared in the same manner as the levo-oxime ; it is an oil having a slight levoro- tatory power: [d\ D = — 4.85° to — 6.67°. Thus, the replace- ment of the oxygen atom in dextrorotatory menthone by the isonitroso-group (NOH), causes a change in direction of its optical rotation. Dextro-menthonoxime hydrochloride is prepared like the levo- compound; it melts at 95° to 100°, and is deliquescent. Its specific rotatory power is [a\ D = — 24.83°. Levo-menthylamine, C 10 H 19 NH 2 , results by the reduction ot levo-menthonoxime with alcohol and sodium. Several substances derived from levo-menthonoxime have been prepared by Wallach ; l they are of special interest since they manifestly stand in a close relation to the olefinic members of the terpene series. Iso-levo-menthonoxime, 1 C 10 H 18 NOH, is formed when levo- menthonoxime is dissolved in chloroform, and the molecular pro- portion of phosphorus pentachloride is added to the solution ; the product is shaken with water when the reaction is complete. It is also obtained by heating a solution of levo-menthonoxime in acetic anhydride with phosphoric anhydride for a short time. It is, however, more conveniently prepared, when twenty grams of levo-menthonoxime are added slowly at first and then more rapidly, with constant agitation, to forty cc. of cold, concentrated sulphuric acid ; the liquid is then warmed very cautiously until all of the oxime is dissolved. The color of the solution changes from yellow to red and brown, and traces of sulphur dioxide are given off ; as soon as the brown color appears, the liquid is poured into a limited amount of ice- water. Most of the isoxime separates in small needles, and the residue may be precipitated by neutrali- zation with sodium hydroxide. (Compare with Beckmann and Mehrländer. 2 ) It is very readily soluble in methyl and ethyl alcohols, and may be recrystallized from hot water; it melts at 119° to 120°, and boils at 295°. Its specific rotatory power is [a\ D = — 52.25°. It behaves as a saturated compound, and does not yield menthone when boiled with acids j dehydrating agents convert it into men- thonitrile. It has been mentioned above that when levo-menthonoxime is dissolved in chloroform and treated with phosphorus pentachlo- ride, and the product is then mixed with water, iso-l-menthonox- i Wallach, Ann. Chem., 278, 302; 277, 154. «Mehrländer, Inaug. Diss. Breslau, 1887; Beckmann and Mehrländer, Ann. Chem., 289, 367. 302 THE TEKPENES. irne is produced ; however, if the reaction-product be distilled in vacuum to remove the chloroform and phosphorus oxychloride, and then heated for some time at 100°, a strong base, C 20 H 35 C1N 2 , is obtained. This amine crystallizes in well defined prisms, and melts at 59° to 60°; it is levorotatory, [a]x,= — 186.35°, and yields stable salts as C 20 H 35 C1N 2 -2HC1. Phosphoric chloride converts dextro-menthonoxime into an iso- meric compound, melting at 88°; an oily product results, together with the solid substance (Beckmann and Mehrländer Menthonitrile, C 9 H 17 CN, may be prepared directly from levo- menthonoxime by the action of phosphoric anhydride ; however, since this reaction takes place very violently, it is better to em- ploy iso-l-menthonoxime. Thirty grams of the latter are dis- solved in eighty cc. of chloroform and treated with forty-five grams of phosphorus pentachloride ; when the evolution of hy- drochloric acid is complete, the chloroform and phosphorus oxy- chloride are removed by distillation in vacuum. If the residue be heated with the free flame under diminished pressure, hydro- gen chloride is split off, and menthonitrile distills over. The re- action takes place in two phases : first, the chlorinated base (m. p. 59° to 60°) is formed from the chloride of iso-l-menthonoxime, and then, at a higher temperature, it is decomposed into menthonitrile and hydrochoric acid : — I. 2C, 0 H 18 NC1 = HCl + C 20 H 35 C1N 2 ; II. C 20 H 35 C1N 2 = HCl + 2C 9 H 17 CN. It can, therefore, be prepared from the pure base, C 20 H 35 C1N 2 . The crude nitrile is washed with sodium hydroxide and purified by distillation with steam. It is an oil, which rotates the plane of polarized light to the left, and boils at 225° to 226°; it has a specific gravity 0.8355 and index of refraction, n^ = 1.44406, at 20°. Menthonitrile differs from iso-l-menthonoxime in behaving as an unsaturated compound ; it immediately decolorizes bromine and permanganate. The formation of this nitrile is, therefore, accompanied by a break in the hexamethylene ring ; hence, menthonitrile and its derivatives belong to the fatty series. Menthonenic amide, 2 C 9 H 17 CONH 2 , is produced by boiling menthonitrile with sodium alcoholate for half an hour ; it crystallizes from hot water in brilliant leaflets, melts at 105° to 106°, and decolorizes bromine. Menthonenic (decenoic) acid, 2 C 9 H 17 COOH, results by the pro- longed action of alcoholic potash on the nitrile or acid amide ; it 1 Beckmann and Mehrländer, Ann. Chem., 289, 367. 2 Wallach, Ann. Chem., 296, 120. M ENTHONE SEMIOXAMAZONE. 303 is conveniently prepared on hydrolyzing the nitrile with sodium ethylate in sealed tubes at 120°. It boils at 257° to 261°, has the sp. gr. 0.918 and n^ = 1.45109 at 20° ; it forms a sparingly soluble silver salt. Oxidation with permanganate yields /3-methyl ad i pic acid. Aminodecoic acid, 1 C 10 H 2l O 2 N, is prepared from menthone isoxime ; it separates from water in well formed crystals, melting at 194° to 195°. Nitrous acid converts it into decenoic acid, C 10 H 18 O 2 , which boils at 257° to 259° and is identical with menthonenic acid. Wheu menthonitrile is reduced in an alcoholic solution with sodium, it yields menthonylamine, C lt) H 19 NH 2 , and oxyhydro- menthonylamine, C 10 H 20 (OH)NH 2 ; the former is an aliphatic isomeride of menthylamine. If menthonylamine be treated with nitrous acid, an alcohol, menthocitronellol, C 1() H 19 OH, is formed ; when this alcohol is oxidized with chromic acid, an aldehyde, menthocitronellal, C 10 H 18 O, is obtained. Dimethyl oetylene glycol, C 10 H 20 (OH) 2 , is formed by the action of nitrous acid upon oxyhy- dromenthonylamine. These substances possess the properties of aliphatic compounds, and bear a close relation to the naturally occurring aliphatic members of the terpene series. They will be described with the aliphatic alcohols and aldehydes. A decoic acid, C 10 H 20 O 2 , an open-chain acid, is formed by heating menthonoxime with an aqueous solution of caustic potash for one hour, at 220° to 230°; it boils at 249° to 251°, has the sp. gr. 0.905, and the refractive index, n D = 1.4373. Its amide crystal- lizes from water and melts at 108° to 109° (Wallach). Menthone semicarbazones, C 10 H 18 = N-NH-CONH 2 . — The de- rivative obtained from dextro-menthone melts at 172°, and has the specific rotatory power, [o]d= —3° (ten per cent, glacial acetic acid solution at 20°); the semicarbazone derived from levo- menthone crystallizes from alcohol in small needles, melts at 178°, and has [a\ D = — 3.67°, under same condition as above. A mixture of the two modifications melts at 175° (Beckmann 2 ). According to Wallach, 3 menthone yields a semicarbazone, melting at 184°. Rimini 3 has also obtained a semicarbazone from perni- trosomenthone, which melts at 192° to 193°. Menthone semioxamazone, 4 C 10 H 18 = N-0 2 O 2 N 2 H 3 , crystallizes from alcohol in wh te needles, and melts at 177°. »Wallach, Ann. Chem., 312, 171. Beckmann, Ann. Chem., 289, 362. »Wallach, Ber., 28, 1955; compare Rimini, Gazz. Chim., 30 [I.], 600; Beckmann, Ann. Chem., 289, 366. *Kerp and Unger, Ber., 30, 585. 304 THE TERPENES. Pemitrosomenthone, 1 C 1() H 18 N 2 0 2 , is formed by the action of so- dium nitrite on an acetic acid solution of menthonoxime; it is an oil, which decomposes at 140° when distilled under diminished pressure. Sulphuric acid and alkalis convert it into menthone. When treated in an alcoholic solution with semicarbazide hydro- chloride and sodium acetate, it is converted into a menthone semi- carbazone, melting at 192° to 193°. Bisnitrosomenthone, [C I0 H lt O(NO)] 3 , results, together with men- thoximic acid, when amy] nitrite is added very slowly and with constant agitation to a well cooled mixture of one hundred grams of menthone and twenty-five grams of concentrated hydrochloric acid ; after two hours standing the mixture is again treated with twenty-five grams of hydrochloric acid, and, in the course of an- other two hours, amyl nitrite is continuously added until the total amount of nitrite employed equals seventy-six grams. The thick reaction-product, containing some crystals, is shaken with ice and treated with a dilute solution of sodium hydroxide, which dis- solves the menthoximic acid. The nitrosomenthone remains un- dissolved, and is obtained in a yield of about eight per cent. It is filtered and crystallized from ether; it separates in lustrous needles, and melts at 112.5° (Baeyer and Manasse 2 ). It may also be prepared in a yield of forty per cent, if acetyl chloride be used in place of hydrochloric acid (Baeyer 2 ). Bisnitrosomenthone reacts with alcoholic hydrochloric acid forming rnenthobisnitrosylic acid, which is a crystalline solid, and monochloromenthone, which is an oil. When monochloromenthone is distilled with sodium acetate and glacial acetic acid, it gives a ketone, C 10 H lfi O, which is apparently identical with menthenone, obtained by Kremers from nitrosomenthene (Baeyer 3 ). Menthoximic acid, C ]0 H 18 O 2 = NOH, is formed together with bis- nitrosomenthone, and is identical with the oxime of oxymenthylic acid, prepared by Beckmann and Mehrländer 4 by the action of hydroxylamine on oxymenthylic acid ; the latter acid is a product of the oxidation of menthol. By treatment with dilute acids, menthoximic acid is readily converted into oxymenthylic acid. According to Baeyer and Manasse, menthoximic acid is pro- duced in a yield of sixty per cent, by the action of amyl nitrite and hydrochloric acid on menthone ; they assume that tertiary nitrosomenthone is first formed, which then combines with the JRimini, Gazz. Chim., 26 [IL], 502; 30 [I.], 600. 2 Baeyer and Manasse, Ber., 27, 1912. s Baeyer, Ber., 28, 1586. ♦Beckmann and Mehrländer, Ann. Chem., 289, 367. NITROMENTHONE. 305 elements of water and is converted into menthoximic acid (di- methyl-^, 6)-oximido-3-octanic acid) : ? H 3 +H 2 0 CH COOH CNOH CH H,C CH, Nitrosomenthone. H 3 C CH 3 Menthoximic acid. H 3 C Oxymenthylic acid. According to Oehler, 1 menthoximic acid melts at 103° ; according to Baeyer and Manasse, it melts at 98.5°. Oxymethylene menthone, ^C^CHCOH) x CO C„ Hi is prepared by the action of sodium and amyl formate on an ethereal solution of menthone; it is a colorless oil, boils at 121° under a pressure of 12 mm. to 13 mm., and has a specific gravity of 1.002 at 15°. It dissolves in alkalis, and decomposes into menthone and the alkali salts of formic acid on boiling its alkaline solutions. It forms a liquid acetyl derivative, boiling at 160° to 162° under 12 mm. to 13 mm. pressure, and a solid benzoyl compound, melting at 75° to 76° (Claisen 2 ). Nitromenthone, C 10 H 17 O(NO 2 ), is formed by heating menthone with nitric acid (sp. gr. 1.075) in a sealed tube. It is a light yellow liquid, boils with slight decomposition at 135° to 140° (15 mm.), and has the sp. gr. 1.059 at 20°/0°. When reduced with tin and hydrochloric acid, it yields amidomenthone, C 10 H 17 - 0-NH 2 , which boils at 235° to 237°; it forms amidomenthonoxime 1 Baeyer and Oehler, Ber., 29, 27. 2 Claisen, Ann. Chem., 281, 394. 20 306 THE TEEPENES. hydrochloride (m. p. 110°) by the action of an excess of hy- droxylamine hydrochloride. Amidomenthonoxime is converted by reduction into a diamine (b. p. 240° to 243°), whose hydro- chloride reacts with potassium nitrite, forming an unsaturated ketone (?), which is possibly isomeric or identical with pulegone. When amidomenthone is reduced, it yields amidomenthol, boil- ing at 254°. An acid, C 10 H 19 NO 4 , is formed by the action of sodium ethylate on nitromenthone ; it boils at 190° to 195° under 13 mm. pres- sure (KonowalofF 1 ). Benzylidene menthone, 3 C 10 H 16 O = CH-C 6 H 5 , is readily obtained in the form of its hydrochloride by saturating a mixture of molec- ular proportions of menthone and benzaldehyde with dry hydro- chloric acid gas ; after standing for about twelve hours in a cold place, the solid hydrochloride is washed with a soda solution to remove excess of hydrogen chloride, is dried, and crystallized from hot alcohol or petroleum ether. On treating the hydro- chloride with a solution of sodium ethylate for twenty minutes on the water-bath, benzylidene menthone is obtained; it is a yellow oil, and boils at 188° to 189° under 12 mm. pressure. Its hy- drochloride (C 10 H 16 O = C 7 H 6 )-HC1, crystallizes from alcohol in white needles, and melts at 140°. The hydrobromide is produced by passing hydrogen bromide into a glacial acetic acid solution of benzylidene menthone ; it crystallizes well, and melts with decom- position at 115° to 116°. According to Martine, 2 benzylidene menthone is formed by the action of benzaldehyde on sodium menthylate; it boils at 195° to 196° (15 mm.), has the rotatory power, [a] D = + 22.8° to + 24.3°, and forms the hydrobromide, melting at 115°. Benzylidene menthonoxime, C 10 H 16 (NOH) = CHC 6 H 5 , crystal- lizes from alcohol or ether in needles and melts at 161°. On reduction with alcohol and sodium, it gives rise to a base, benzyli- dene menthylamine, C 17 H 23 NH 2 , which boils at 200° to 205° under 10 mm. pressure. Benzyl menthol, 3 C 10 H lg (OH)-CH 2 -C 6 H 5 , is produced by the re- duction of benzylidene menthone or its hydrochloride with sodium and alcohol; it separates as a thick oil, boiling at 181° to 183° (10 mm.). After standing during several months, a small portion of this oil solidifies, and, after recrystallization from ether, forms colorless crystals, melting at 111 0 to 112°. Both oil and crystals iKonowaloff, Compt. rend., 121, 652; Ber., 31, 1478. "Martine, Compt. rend., 1S3, 41. s Wallach, Ann. Chera., 305, 261; Ber., 29, 1595; compare Martine, Compt. rend., 133, 41. MENTHONE DICARBOXYLIC ACID. 307 have the same composition, C 17 H 25 OH, and are probably two physical-isonieric modifications of the same compound. When treated with phosphorus pentoxide, benzyl menthol yields a hy- drocarbon, methyl isopropyl hexahydrofluorene, CLEL, boiling at 153° to 155° (10 mm.). Benzyl menthone, C 17 H 24 0, results on the oxidation of benzyl menthol in glacial acetic acid solution with chromic acid ; it is a viscous oil, boils at 177° to 179° (10 mm.), and yields an oily oxime ; on reduction, this oxime gives rise to benzyl menthylamine. Menthone pinacone, 1 C 20 H 38 O 2 , is formed on reducing menthone in ethereal solution with sodium j it melts at 94°. When menthone in an absolute ethereal solution is treated with sodium wire, and is then saturated with carbon dioxide, a mixture of products is obtained, which contains, besides unchanged men- thone and menthol, menthone pinacone, menthone carboxylic and dicarboxylic acids. 2 Menthone carboxylic acid, C 10 H 17 OCOOH, is a heavy, color- less oil, is sparingly soluble in water, and its solution gives a violet coloration with ferric chloride; when heated with dilute sulphuric acid, it is reconverted into menthone. Its silver salt is a white solid. On treating the acid with nitrous acid at ordinary temperature, isonitrosomenthone, C 10 H 1? O(NOH), and an ortho-diketone, C 10 H 16 O 2 , are formed ; the former is an oil, is soluble in alkalis, and yields menthone amine, C 10 H 17 ONH 2 , on reduction with zinc dust and acetic acid ; the ortho-diketone is a reddish oil, insoluble in alkalis. Menthone dicarboxylic acid, C ]0 H 16 O(COOH) 2 , melts and decom- poses at 140° to 141°. It should be mentioned that Flatau and Labbe 3 separated a ketone, boiling at 204° to 206°, from Bourbon geranium oil; they called this ketone " a-menthone" It yields a semicarbazone, melting at 180°. It will probably be safe to regard "a-men- thone" as identical with ordinary levo-menthone, until a more complete investigation shall prove to the contrary. _ A ketone, C 10 H lg O, was obtained by Kondakoff 1 from the ethereal oil of buchu leaves ; this ketone is called ketomenthone. It is a colorless liquid with a peppermint-like odor; it boils at 208.5° to 209.5° under 760 mm. pressure, has the sp. gr. 0.9004 at 19°/19°, Beckmann, Journ. pr. Chem., 55 [II.], 14. 2 Oddo, Gazz. Chim., 27 [II.], 97. 3 Flatau and Labb6, Bull. Soc. Chim., 19 [III.], 788; compare Schimmel & Co., Semi-Annual Report, Oct., 1898, 52. «Kondakoff, Journ. pr. Chem., 54 [II.], 433; Kondakoff and Bachtscheeff, Journ. pr. Chem., 63 [IL], 49. 308 THE TERPENES. the optical rotation, [a] D = — 16°6', the index of refraction, n^ = 1.45359, and molecular refraction, 46.28. Its oxime is liquid and optically active. When ketomenthone is reduced in methyl alcoholic solution with sodium, it yields a solid and a liquid menthol, C 10 H 19 OH. The solid menthol crystallizes in needles, melts at 38.5° to 39°, has the sp. gr. 0.9006 at 32°/32°, and the index of refraction, Uj) = 1.45869, at 32°; its benzoate melts at 82°. When this menthol is treated with phosphoric oxide, it is converted into a menthene, C 10 H lg , which boils at 166.5° to 168.5° (785 mm.), has the sp. gr. 0.8112 at 19°, n^ = 1.45109, and - 13°46 / . The isomeric, liquid menthol boils at 106.5° to 109° (18 mm.), has the sp. gr. 0.9041 at 21.6°, n,, = 1.461793, and [«] 0 = + 26°30'; it yields a levorotatory menthene. Neither of these isomeric menthols appears to be identical with the natural menthol. Sym-menthone^l.S-methylisopropylcyclohexanone-S), C 10 H 18 O, is formed by oxidizing sz/m-menthol with chromic acid ; it is a colorless oil of peppermint-like odor, and readily forms a crystalline deriva- tive with acid sodium sulphite. It boils at 222° (749 mm.), has the sp. gr. 0.9040 at 18°/4°, the refractive index, n^ = 1.45359, at 18°, and the molecular refraction, R = 45.98. Its semicarbazone crystallizes from benzene and melts at 176° to 177°. 7. MENTHOL, C 10 H 19 OH. Menthol, 2 formerly designated as " rnentha camphor," or "pep- permint camphor," occurs, together with menthone, menthene and terpenes, in peppermint oil. It is deposited in crystals when the essential oil is cooled ; for its preparation, however, it is better to first distill off the terpenes and menthene, and then cool the remaining oil. When menthone, C 10 H 18 O, is reduced in the presence of an excess of nascent hydrogen, as with sodium and alcohol or water, menthol is the only product ; but with sodium and solvents which do not themselves liberate hydrogen, as absolute ether, some men- thone pinacone, C 20 H 38 O 2 , is formed, together with menthol. 3 Levo- and dextro-menthone yield by both methods a strongly levoro- tatory mixture of menthols. From this mixture the natural i Knoevenaugel and Wiedermann, Ann. Chem., 297, 169. "Oppenheim, Ann. Chem., 120, 350; 130, 176; Journ. pr. Chem., 91, 502; Gorup-Besanez, Ann. Chem., 119, 245; Beckett and Wright, Journ. Chem. Soc., 1 [2], 1; Ber., 1875, 1466; Charabot, Compt. rend., 130, 518. 3 Beckmann, Journ. pr. Chem., 55 [II.], 14. MENTHOL. 309 levo-menthol (m. p. 43°), and a dextrorotatory isomenthol (m. p. 78° to 81°, [a\ D = + 2°) may be separated. Menthol and menthone may be separated by converting the latter into its oxime, extracting with ether, evaporating the extract, and again extracting with dilute sulphuric acid. This removes the menthone in the form of its oxime, and leaves the menthol ; it does not give rise to a transformation into optical isomerides (Beckmann). Menthol is readily prepared when an ethereal solution of men- thone is treated successively with sodium and water, these opera- tions being repeated several times. By this method it is possible to convert the menthone, occurring together with menthol in pep- permint oil, into menthol, thus considerably increasing the yield of the latter compound (Beckmann 1 ). Menthol is also formed in the reduction of pulegone, 2 C 10 H 16 O. It crystallizes in colorless, brilliant prisms, which have a strong smell of peppermint, and a burning taste; it melts at 43°, boils at 212°, and possesses a specific gravity of 0.890 at 15°. Its molecular refractive power 3 is 47.52, and its heat of combustion 4 equals 1509.1 calorimetric units (for one molecule expressed in grams). Menthol obtained from peppermint oil is optically levo- rotatory, [«J^ = — 59° 6'. Chromic acid converts menthol into menthone. Phosphoric anhydride, zinc chloride, potassium bisulphate, etc., dehydrate it, forming menthene, C 10 H 18 ; this hydrocarbon is more readily pre- pared by distilling menthyl chloride with quinoline. According to Beckmann, 5 menthene also results by the action of concentrated sulphuric acid on menthol, whilst Wagner 6 finds that this reaction gives rise to a polymeric product, C 2Ü H 36 , together with cymene sul phonic acid and hexahydrocymene (menthane), C 10 H 20 . The transformation of menthol into cymene may be effected by heating with anhydrous copper sulphate at 250° to 280° (Brühl 7 ). Hexa- hydrocymene (" menthonaphthene "), C 10 H 20 , is produced by heating menthol with hydriodic acid and red phosphorus at 200° ; it boils at 169° to 170.5° (Berkenheim 8 ). Potassium permanganate oxidizes menthol, forming oxymen- thylic (ketomenthylic) acid, C 10 H 18 O 3 , carbonic, formic, propionic 'Beckmann, German Patent, No. 42,458; Ber., 22, 912. 2 Beckmann and Pleissner, Ann. Chem., 262, 1. 3 Brühl, Ber., 21, 457. 4 Luginin, Ann. Chim. Phys. [5], 23, 387. 5 Beckmann, Ann. Chem., 250, 358. 6G. Wagner, Ber., 27, 1637; St. Tolloezko, Chem. Centr., 1895 [I.], 543; 1898 [I.], 105. 'Brühl, Ber., 2h, 3374. 8 Berkenheim, Ber., 25, 686. 310 THE TERPENES. and butyric acids, together with the dibasic /5-methyl adipic acid (Arth's 1 /9-pimelic acid), C 7 H 12 0 4 . Oxymenthylic acid (2, 6 -dimethyl octan-3-onoic acid), C 10 H 18 O 3 , is a thick liquid, sparingly soluble in water, and boils at 280° at ordinary pressure, or at 173° to 175° (15 mm.) ; with alkalis it forms crystalline salts which are readily soluble, whilst its silver salt is sparingly soluble. Its semicarbazone 2 crystallizes in prisms and melts at 152°. Its methyl ester boils at 136° to 137° (17 mm.), and the ethyl ester at 145° (15 mm.). When the ethyl ester is heated with sodium and xylene, it yields a 1, 3-dihetone 2 (isobutyryl methyl ketopentamethylene), C 10 H 16 O 2 ; it boils at 115° to 116° (25 mm.), forms a dioxime (m. p. 144°), and is reconverted into oxymenthylic acid on heating with aqueous potash. Oxymenthylic acid is most conveniently prepared by the oxida- tion of menthol in an acetic acid solution with chromic anhydride. It is a ketonic acid and is converted into menthoximic acid 3 (m. p. 96.5°), by treating with hydroxy lamine. /2-Methyl adipic acid 4 (Arth's ß-pimelic acid), 0 7 H 12 O 4 , melts at 88.5° to 89°. Mehrländer described it as normal propyl succinic acid, but Arth 5 proved the error of this statement. According to Semmler, 6 this acid is likewise formed, together with acetone, during the oxidation of pulegone with permanganate. The constitution of the oxidation products of menthol are, therefore, expressed by the same formulas as given under nien- thone. The sodium salt 7 of 1-menthol is formed by heating the latter compound with sodium in an atmosphere of hydrogen. When it is heated with acid anhydrides for several hours at 160° to 170°, it yields the corresponding esters of menthol ; the stearate, pre- pared in this manner, melts at 39°. Methylenic acetal of menthol 8 (dimentholic formal or dimenthyl- methylal), CH 2 (O-C ]0 H 19 ) 2 , is produced by the condensation of menthol and formaldehyde in the presence of mineral acids ; it separates from alcohol in colorless needles, melts at 56.5°, and boils with slight decomposition at 337°; [a] D = — 77.94° at 24°. It is indifferent to boiling acids and alkalis. JArth, Ann. Chim. Phys., 7 [6], 440. 2 Baeyer and Oehler, Ber., 29, 27. 3 Beckmann and Mehrländer, Ann. Chem., 289, 367. 4 Manasse and Rupe, Ber., 27, 1818. sArth, Ber., 21, 645, Ref. eSemmler, Ber., 25, 3515; 26, 774. 7 Beckmann, Journ. pr. Chem., 55 [II.], 14. »Brochet, Compt. rend., 128, 612; Wedekind, Ber., 34, 813. MENTHYL, BENZOYL ESTER. 311 Chloromethyl menthyl oxide, 1 C 10 H 19 O-CH 2 C], is obtained by sat- urating a mixture of menthol and formalin solution with hydro- gen chloride at the temperature of the water-bath. It is a color- less oil, boils at 160° to 163° under 13 mm. to 16 mm. pressure, has the sp. gr. 0.9821 at 4° and the rotatory power, [«]/> = — 172°. 57, at 27°. The action of water converts it into menthol, formaldehyde and hydrogen chloride ; when distilled under re- duced pressure it suffers partial decomposition and yields methy- lenic acetal of menthol, C 21 H 40 O 2 . Menthyl acetoacetate, 2 C 14 H 25 0 2 , is obtained by heating menthol and ethyl acetoacetate at 140° to 150° during four hours ; it crystallizes in needles, melts at 30° to 32°, boils at 145° under 11 mm. pressure, and has the specific rotatory power, [«] D = — 56.6°. Its phenylhydrazone melts at 81° to 83°. Menthyl ethyl ether, C 10 H 19 OC 2 H 5 , is produced by the action of ethyl iodide on sodium menthylate. It is a liquid, boiling at 211.5° to 212° under 750 mm., and has a slight odor of menthol; it has a specific gravity of 0.8513 at 20° or 0.8535 at 17.1°, and the refractive power, n D = 1.44347, at 17.1° (Brühl 3 ). Menschutkin 4 investigated the speed of the ester formation of menthol and from his results determined that it is a secondary alcohol. Menthyl acetate, C 10 H 19 O-COCH 3 , is a thick, strongly refractive liquid, which boils at 224° and is levorotatory, [a\ D = — 114°. (Compare with Power and Kleber 6 ). Menthyl butyrate, C 10 H 19 O'COC 3 H 7 , boils at 230° to 240° and has the rotatory power, [«]# = — 88°8'. The following esters were prepared by Arth. 5 Menthyl succinoxyl ester, C 10 H 19 O-CO-CH 2 -CH 2 -COOH, melts at 62°, and has the specific rotatory power, [a] Z) = — 59.63°. Menthyl succinyl ester, C 2 H 4 (COOC 10 H 19 ) 2 , forms triclinic crys- tals, and melts at 62°; it decomposes into succinic acid and men- thene when heated in a sealed tube at 220°. Its specific rotatory power is [a]^ = — 81.52°. Menthyl benzoyl ester, 7 C 6 H.COOC 10 H 19 , crystallizes in triclinic crystals, melts at 54°, and has the rotatory power, [a\ D = - 90.92°. » Wedekind, German Patent, No. 119,008; Ber., 84, 813. 2 Cohn, Monatsh., 21, 200. »Brühl, Ber., 24, 3375 and 3703. * Menschutkin, Journ. Russ. Chem. Soe., 18, 569. sArth, Ann. Chim. Phys. [6], 7, 433 to 499; Ber., 19, 436, Ref. «Power and Kleber, Pharm. Rund., 12, 162; Archiv, d. Pharm., 232, 653. 'Compare with Beckmann, Ann. Chem., 262, 31; Journ. pr. Chem., 55 [IL], 16. 312 THE TERPENES. Menthyl phthaloxyl ester, HOOCC 6 H 4 -CO-OC 10 H 19 , melts at 110°, and has the specific rotatory power, [0]^ = — 105.55°. Its magnesium salt is almost insoluble in water. Menthyl phthalyl ester, C 6 H 4 (COOC 10 H 19 ) 2 , separates from ether in triclinic crystals, and melts at 133°. [a] /) = — 94.72°. Menthyl carbonate, CO(OC 10 H 19 ) 2 , is obtained, together with menthyl carbamate, when cyanogen is allowed to act on sodium menthylate suspended in toluene ; the toluene is removed by steam distillation when the reaction is complete. The carbamate crystallizes from the cold residue, and is filtered off ; the carbon- ate is obtained by evaporation of the filtrate. It is recrystallized from alcohol or toluene, and melts at 105°. It is also formed when a well cooled mixture of a solution of menthol in chloroform and pyridine is treated very slowly with a solution of carbonyl chloride in chloroform ; after standing for a day in a cold place, the product is distilled with steam, the solid residue is washed with hot water, and crystallized from alco- hol (Erdmann x ). Menthyl carbamate, C 10 H ]9 O-CO-NH 2 , is purified by recrystal- lizing the crystals, obtained as suggested under the preceding compound, from alcohol. It crystallizes in orthorhombic prisms, melts at 165°, and has the specific rotatory power, — 85.11°. It combines with benzaldehyde, forming benzylidene menthyl carbamate; this compound melts at 143°. Menthyl phenylcarbamate, C 10 H 19 O-CO-NHC 6 H s , is formed by the combination of phenylcarbimide with menthol ; it separates from alcohol in silky needles, melting at 111° (Leuckart 2 ). When this compound, prepared from natural menthol, is saponified with alcoholic sodium ethylate at 150°, it yields some inactive menthol, 3 melting at 49° to 51°. Sodium menthylxanthate, 1 C 10 H 19 OCS*SNa, results when carbon bisulphide is allowed to act on sodium menthylate suspended in ether. The free acid is an oil, which decomposes very readily. The dark, amorphous cupric salt, which is precipitated from aqueous solutions of the sodium salt by copper sulphate, is con- verted into the yellow, crystalline cuprous salt, C 10 H 19 OCS-SCu, by heating. Methyl menthylxanthate, 4 C ]0 H 19 OCS-SCII 3 , is formed when a solution of menthol in dry toluene is successively treated with sodium, carbon bisulphide, and methyl iodide; it melts at 39°. 'Erdmann, Journ. pr. Chem., 56 [II.], 1. 2 Leuckart, Ber., 20, 115. »Beckmann, Journ. pr. Chem., 55 [II.], 14. * Bamberger and Lodter, Ber., 23, 213. MENTHYL CHLOKIDE. 313 When submitted to distillation, it yields methyl mercaptan and a menthene, C 10 H 18 , of a high specific rotatory power, [a\ D = 114.77° to 116.06°. Menthyl dixanthate, 1 (C 10 H 19 O) 2 C 2 S 4 , is formed by the conden- sation of sodium menthylxanthate with iodine ; it forms yellow crystals. When distilled it gives a menthene, having the rotatory power, [a] B = 111.56°. A number of the fatty acid esters of menthol have been pre- pared, and investigated by Tschügaeff. 2 Menthyl chloride, C 10 H 19 C1, bromide and iodide, prepared by the action of the phosphorus pentahalogen derivatives on men- thol, are identical with menthene hydrochloride, hydrobromide and hydriodide, which are produced by the addition of the halogen hydride to menthene. They react like derivatives of tertiary menthol, but are doubtless to be regarded as mixtures of at least two isomerides. Menthyl chloride (menthene hydrochloride 3 ), C 10 H 19 C1, is formed, together with menthene, by treating menthol with phosphorus pentachloride, by heating menthol with concentrated hydrochloric acid, or by heating menthene with concentrated hydrochloric acid at 205° for six hours. It boils at 209.5° to 210.5°, and has the specific gravity 0.947 at 15°. It yields menthene when treated with zinc dust and acetic acid or with sodium mentholate ; on re- duction with sodium and alcohol, it gives rise to hexahydrocymene (menthane), C 10 H 20 . According to Kursanoff, 4 when menthyl chloride is dissolved in ether and the solution is boiled with sodium, it yields a mix- ture of menthene, menthane, and two dimenthyls, C 20 H 38 , one of which is a liquid. The crystalline dimenthyl, C 20 H 3g , is readily soluble in ether and benzene, and crystallizes from cold alcohol or benzene in well developed crystals, which melt at 105.5° to 106°, and boil at 185° to 186° (21 mm.); it has the specific rotatory power, [a]i,= — 51° 18', in a 19.4 per cent, benzene solution. The liquid dimenthyl is probably a stereoisomeride of the crystal- line derivative. The formation of the crystalline dimenthyl from crude menthyl chloride, as well as by the action of sodium on an ethereal solu- tion of menthyl iodide, indicates that the crude halogen esters of 1 Tschügaeff, Ber., 32, 3332. 2 Tschügaeff, Ber., 31, 364. 3 Waller, Ann. Chem., 32, 292; Oppenheim, Ann. Chem., 130, 177; Berken- heim, Ber., 29, 686; Kondakoff, Ber., 28, 1619; Jünger and Klages, Ber., 29, 317 ; Kursanoff, Journ. Rubs. Phys. Chem. Soc, 33, 289. *Kursanoff, Journ. Russ. Phys. Chem. Soc, 33, 289. 314 THE TERPENES. menthol contain some secondary compounds, together with deriv- atives of tertiary menthol (Kursanoff). When 1-menthyl chloride is treated with zinc ethyl, it gives rise to ethyl menthane, C 10 H 19 .C 2 H 5 ; the latter boils at 209° to 210° at 730 mm. pressure, has the sp. gr. 0.8275 at 0°/0°, and the specific rotation, [a] i) = — 12° 15'. Menthyl bromide (menthene hydrobromide 1 ), C 1(} H 19 Br, is pro- duced by the action of phosphorus pentabromide or hydrobromic acid on menthol ; it also results by treating menthene with a saturated solution of hydrobromic acid. It boils at 100° to 103° at 13 mm., and has the specific gravity 1.155 to 1.166 at 23°. Menthyl iodide (menthene hydriodide 2 ), C 10 H lfl I, is obtained by the action of hydriodic acid on menthol or menthene ; it boils at 124° to 126° (18 mm.), and has the specific gravity 1.3155 at 16.5°. Moist silver oxide converts it into tertiary menthol, thus giving rise to a transformation of secondary into tertiary menthol. Menthol is a saturated secondary alcohol, and its constitution is represented by the accompanying formula : H.jC CH, H 2 C CHOH CH k H 3 C CH 3 Menthol. It has already been mentioned that when d- or 1-menthone is reduced with sodium, the corresponding d- and 1-menthols are not obtained, but rather a strongly levorotatory mixture of menthols is formed, from which the ordinary 1-menthol (m. p. 43,° [a\ D = — 49.3°), and a dextrorotatory isomenthol may be separated. Isomenthol 3 is separated from the mixture by converting the menthols into their benzoyl esters; menthyl benzoate is a solid (m. p. 54°), while isomenthyl benzoate is a liquid. On saponifi- cation of the liquid ester, isomenthol is obtained and crystallizes after standing some time. It melts at 78° to 81° and is slightly dextrorotatory, [a] B = + 2.03°. On oxidation with chromic iKondakoff, Ber., 28, 1618. 2 Kondakoff and Lutschinin, Journ. pr. Chem., 60 [IL], 257; Berkenheim, Ber., 25, 696. 3 Beckmann, Journ. pr. Chem., 55, 14. CIS-SYMMETRICAL MENTHOL. 315 acid, isomenthol yields a dextr o-menthone, which has a stronger dextrorotatory power than the d-menthone prepared by the inver- sion of 1-menthone. Dextro-menthol, corresponding to the natural levo-menthol, has not yet been obtained. In an investigation of the ethereal oil of buchu leaves, Kondakoff' 1 found that the best samples of oil from Barosma betulina and B. serratifolia contain about ten per cent, of hydro- carbons, C 10 H 16 (d-limonene and dipentene), sixty per cent, of ketomenthone, C 10 H lg O (see under raenthone), and five per cent, of diosphenol. Diosphenol, C 10 H 18 O 2 or C 10 H 16 O 2 , is an inactive, phenolic alde- hyde, and melts at 82°. On reduction with hydriodic acid and phosphorus at 210°, it yields a hydrocarbon, C 10 H 20 , of the hexa- hydrocymene series ; it boils at 165° to 168° (762 mm.). When reduced with sodium and alcohol, diosphenol gives an inactive menthol, a crystalline glycol, C 10 H 20 O 2 , and a stereomeric, liquid glycol, C 10 H 20 O 2 . The inactive menthol, C 10 H 19 OH, is volatile with steam, boils at 215° to 216° (763 mm.), has a sp. gr. 0.9052 at 20°, and the index of refraction, n^ = 1.464456. It yields an inactive iodide, C 10 H 19 I, which boils at 126.5° (17 mm.). When this iodide is treated with alcoholic potash, an active menthene, C 10 H 18 , results, which boils at 168° to 169°, has the sp. gr. 0.8158 at 19.8°, xx D = 1.45909, and [a] D = -37'. The crystalline glycol, C 10 H 20 O 2 , is optically active and odorless; it crystallizes in colorless needles, melts at 92°, has a sharp, cool- ing taste, and is not volatile with steam. When heated with hy- driodic acid it gives a liquid menthyl iodide, C 10 H 19 I, which boils at 112° to 114° (9 mm.), has the sp. gr. 1.359 at 20.6°, and n*« 1.520771. The liquid glycol, C 10 H 20 O 2 , is stereomeric with the crystalline glycol ; it boils at 141.5° to 145° (13 mm.), has the sp. gr. 0.995 at 21.6°, and n D = 1.47877. In conclusion, two alcohols, C 10 H 19 OH, isomeric with menthol, but synthetically prepared, should be mentioned. Cis-symmetrical menthol (cis-1, 3-methyl isopropyl cyclohexanol- 5), C 10 H 19 OH, is an alcohol, isomeric with natural menthol, which Knoevenagel 2 prepared synthetically by the action of hydriodic acid, zinc dust and glacial acetic acid on £ra?i.s-hexahydro-l, 3, 5- carvacrol, C 10 H 17 OH. It boils at 226° to 227° (760 mm.), has a specific gravity 0.9020 and refractive index, n D = 1.46454, at kondakoff and Bachtscheeff, Journ. pr. Chem., 63 [IL], 49. 2 Knoevenagel and Weidermann, Ann. Chem., 297, 169. 316 THE TERPENES. 13.6°, and a molecular refraction, M= 47.67. It has an odor suggesting that of natural menthol, is not acted upon by bromine or potassium permanganate, but is converted into symmetrical menthone on oxidation with chromic acid. Its acetate boils at 235° to 236° (752 mm.), and the phenylurethane crystallizes from a mixture of alcohol and petroleum ether, and melts at 88°. The chloride, bromide and iodide are liquids. An alcohol, 1 C I0 H 19 OH, isomeric with, and having the same structure as, natural 1-menthol, is formed by the reduction of 3-methyl-6-isopropyl-J' 2 -keto-R-hexene. It boils at 202° to 204°, has the sp. gr. 0.910 at 20°, and possesses an odor recalling that of peppermint; it does not yield a phenylurethane. When treated with phosphoric anhydride, it gives rise to an inactive menthene, C 1(J H 18 , boiling at 165° to 167°. 8. TERTIARY CARVOMENTHOL, C 10 H 19 OH. Tertiary carvomenthyl iodide, C 10 H 19 I, is formed, when carvo- menthene is dissolved in acetic acid and treated with hydriodic acid ; the iodine atom in this compound is attached to that atom of carbon which carries the methyl group. This follows the common rule that when a halogen hydride combines with an un- saturated compound, the halogen atom attaches itself to the least hydrogenized carbon atom. If this iodide, C ]0 H ]9 I, be dissolved in acetic acid, and decomposed with silver acetate, it is partially reverted into carvomenthene, while the remaining portion is con- verted into the acetate of tertiary carvomenthol (Baeyer 2 ). ; H S CH S COCOCH 3 H 2 C ^CH 2 H 2 (^ CH 2 H 0h C 3 H T G,H 7 c 3 H T Carvomenthene. Tertiary carvomenthyl Tertiary carvomenthyl iodide. acetate. Tertiary carvomenthol is obtained by the hydrolysis of its acetate. It 3 is also produced by treating carvomenthyl chloride or bromide with moist silver oxide ; a small quantity of the com- pound, C 10 H 22 O 3 (m. p. 101° to 102°), is formed at the same time. 'S. H. Baer, Inaug. Diss., Leipzig, 1898; Schimmel & Co., Semi- Annual Report, Oct., 1898, 49. 2 Baeyer, Ber., 26, 2270. 3 Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257. TERTIARY MENTHYL METHYL ETHER. 317 Tertiary carvomenthol has a slight odor, and. boils at 96° to 100° under a pressure of 17 mm. It reacts as a tertiary alcohol towards chromic acid. Hydrobromic acid in a glacial acetic acid solution converts it at once into tertiary carvomenthyl bromide ; l this is a heavy oil, which yields carvomenthene, boiling at 174.5°, when distilled with quinoline. 9. TERTIARY MENTHOL, C 10 H 19 OH. Tertiary menthyl iodide is produced by treating menthene with an acetic acid solution of hydrogen iodide ; if this halogen deriva- tive be decomposed with silver acetate and acetic acid, it gives menthene and the acetate of tertiary menthol (Baeyer 2 ). 5 CH 3 CH, H 2 pH, (X3COCH s C 3 H, C 3 h t C 3 H 7 Menthene Tertiary menthyl Tertiary menthyl iodide. acetate. h/V, ^ H 2 C CH, ^ H 2 C f Tertiary menthol is obtained by the saponification of its acetate. It is also formed by the action of moist silver oxide on menthyl iodide. 1 Tertiary menthol is produced by heating menthene with tri- chloracetic acid at 70° to 90° for half an hour, and agitating the product with potash for 12 hours. 3 It has a faint odor of peppermint, is decomposed on distillation at ordinary pressure, but boils undecomposed at 97° to 101° under a pressure of 20 mm. It solidifies to a vitreous mass when cooled with solid carbonic anhydride. It behaves as a tertiary alcohol towards chromic acid. Tertiary menthyl bromide, C 10 H ]9 Br, is readily prepared by treat- ing a glacial acetic acid solution of tertiary menthol with hydrogen bromide. It yields menthene, boiling at 167.5°, when heated with quinoline. Tertiary menthyl methyl ether, C 10 H 19 OCH 3 , is obtained, together with a monomethyl terpine, by the following method. 'Kondakoff and Lutschinin, Journ. pr. Chem., 60 [II.], 257. 2 Baeyer, Ber., 26, 2270. sMasson and Reychler, Ber., 29, 1843. 318 THE TEKPENES. The methyl ether of crystallized terpineol (m. p. 35°) is shaken with hydriodic acid (sp. gr. 1.7) for fifteen minutes, thus forming the hydriodide. This is washed with sodium sulphite and bicar- bonate, extracted with ether, and the ethereal solution dried and treated directly with glacial acetic acid and zinc dust, care being taken not to allow the temperature to rise above 25°. When the reaction is complete, an excess of sodium hydroxide is added, and the product distilled with steam. Some terpinyl methyl ether is regenerated during the reaction, and is eliminated by treating the crude product with potassium permanganate. The acetate of a methyl terpine, C ip H 18 (OCH 3 )OCOCH 3 , is also formed by the re- placement of the iodine atom in the above-mentioned hydriodide with the acetyl group. This acetate yields monomethyl terpine by boiling with sodium hydroxide. *The terpine is separated from menthyl methyl ether by distillation over the alloy of sodium and potassium, the terpine being quantitatively retained in the residue, while the pure methyl ether of tertiary menthol is found in the distillate (Baeyer 1 ). It has a faint odor of cymene, boils at about 210°, and is not attacked by permanganate. It combines with hydrobromic acid, forming tertiary menthyl bromide, which is converted into menthene on distillation with quinoline ; the resultant menthene boils at 167.5°, and forms a nitrosochloride, melting at 146°. Baeyer's conclusions as to the orientation of these compounds are opposed to the views regarding the constitution of terpineol (m. p. 35°), which have been expressed by both Wallach and Tiemann. (Compare also with the publications of Kondakoff. 2 ) 10. TERPINE, C 10 H 18 (OH) 2 . _ Terpine is the alcohol corresponding to dipentene dihydrochlo- ride. It was believed until quite recently that the constitutions of these two compounds were represented by the formulas : CH ; A 1 H 2 C CH COH 9 f 1 ' h/ x ch s H 2 C SpH, and jjA fa m ^coh X H k h bC CH 3 H s cf \h, Dipentene dihydrochloride. Terpine. i Baeyer, Ber., 26, 2560. ^Kondakoff, Ber., 28, 1618; Journ. pr. Chem., 60 [II.], 257. TRANS-TERPINE. 319 This terpine formula, however, does not readily conform with the formation of terebic acid by the oxidation of terpine, since terebic acid possesses the constitution : — HOÜC— CH— CH H,C CH, Moreover, the oxidation of terpine 1 with chromic anhydride yields the keto-lactone, C 10 H 16 O 3 , which is obtained by the oxida- tion of terpineol (m. p. 35°). Hence, it is possible that a chlorine atom in dipentene dihydrochloride and a hydroxyl-group in ter- pine are not attached to carbon atom 4, but rather to carbon atom 8 ; the two compounds would then be represented by the for- mulas : — H s CH 3 CI QOH H,C CH, H,C CH, and \y CH COH H 3 C CH 3 Terpine. The determination of the exact constitution of terpine is, natu- rally, of fundamental importance for the orientation in the terpene series. Perhaps two terpines exist which correspond to the above formulas, since Baeyer 2 has found that the dihydrochloride and dihydrobromide of dipentene, and terpine itself exist in two forms designated as the trans- and cis-modification. Trans-terpine corresponds to the well known dipentene dihydro- bromide, melting at 64°, and is prepared by dissolving this com- pound in ten times its amount of glacial acetic acid and gradually treating the ice-cold solution with an excess of silver acetate. The product is filtered after standing for some time, and the filtrate is neutralized with soda and extracted with ether. The ethereal solu- tion is treated with alcoholic potash to saponify the acetyl com- pound, and the reaction-product is then distilled with steam ; hydrocarbons and terpineol are so removed, while trans-terpine is obtained from the cold residue (Baeyer 2 ). 'Tiemann and Schmidt, Ber., 28, 1781. 2 Baeyer, Ber., 26, 2865. 320 THE TERPENES. Trans-terpine crystallizes without water of crystallization, melts at 156° to 158° and boils at 263° to 265°. It is readily soluble in alcohol, more sparingly in water, ether and ethyl acetate, and separates from the latter solvent in beautiful, short prisms or six- sided tablets, having a strong, vitreous luster. When it is treated with hydrogen bromide in a glacial acetic acid solution, it yields almost exclusively trans-dipentene dihydrobromide, melting at 64°. Dilute sulphuric acid converts trans- and cis-terpine into terpineol. Cis-terpine corresponds to cis-dipentene dihydrobromide (m. p. 39°), and may be obtained from this dihydrobromide according to the method described under trans-terpine (Baeyer 1 ). While many terpenes yield trans-dipentene dihydrochloride and dihydrobromide exclusively or in preponderant quantities, on the other hand the transformation of the same terpenes into terpine always gives cis-terpine, which has the peculiarity of crystallizing with one molecule of water ; in such cases, therefore, terpine hydrate, C 10 H lg (OH) 2 + H 2 0, is always produced and may be converted into cis-terpine by the elimination of the water of crystallization. It further merits notice that Tiemann and Schmidt 2 do not re- gard terpine hydrate as a terpine containing water of crystalliza- tion, but rather as an aliphatic alcohol. Terpine hydrate, C 1() H 18 (OH) 2 + H 2 0, results when pinene or limonene (dipentene) is allowed to stand in contact with dilute mineral acids for a long time at ordinary temperature. Of the following methods which have been proposed for its preparation, the one suggested by Hempel is to be preferred. According to Wiggers 3 and Deville, 4 a mixture of three liters of eighty-five per cent, alcohol, one liter of ordinary nitric acid, and four liters of turpentine oil is allowed to stand for one or one and one-half months. According to Tilden, 5 two and one-half volumes of turpentine are mixed with one volume of methyl alcohol and one volume of nitric acid of sp. gr. 1.4; the mixture is allowed to stand for two days, and is then poured into a flat basin, small quantities of methyl alcohol being added every two days. According to Hempel, 6 whose method was employed by Wal- lach, 7 a mixture of eight parts of turpentine oil, two parts of alco- 1 Baeyer, Ber., 26, 2865. ^Tiemann and Schmidt, Ber., 28, 1781. 3 Wiggers, Ann. Client., 57, 247. * Deville, Ann. Chem., 71, 348. 5 Tilden, Jahresb. Chem., 1878, 638. e Hempel, Ann. Chem., 180, 73. 7 Wallach, Ann. Chem., 227, 284. TEEPINE HYDRATE. 321 hol, and two parts of nitric acid of sp. gr. 1.255 is placed in flat basins. After standing for a few days the mother-liquor is poured off from the crystals of terpine hydrate, and is neutralized with an alkali, after which treatment a second crop of crystals separates. The preparation of this compound is most successful during the cool seasons of the year. 1 Terpine hydrate is also formed when dipentene dihydrochloride is treated with aqueous alcohol, 2 or when limonene hydrochloride is mixed with water and allowed to stand for some time. 3 It re- sults if terpineol be shaken with dilute acid for a considerable time. It crystallizes from alcohol in transparent, well defined, mono- clinic 4 prisms, and dissolves in 200 parts of cold, and twenty-two parts of boiling water; 5 14.49 parts of terpine hydrate dissolve in 100 parts of eighty-five per cent, alcohol 4 ; it is insoluble in ligroine. Contrary to the earlier publications, Wallach 6 found that when it is heated in a capillary tube it commences to coagu- late and soften above 100°, and melts at 116° to 117°, the fusion being accompanied by frothing and sublimation of some of the substance due to the removal of water of crystallization. It does not melt when boiled with a quantity of water insufficient for its solution. On distillation the water of crystallization is first given off and carries over some terpine hydrate ; the anhydrous terpine, C 10 H 18 (OH) 2 , then boils at 258° (corr.). Terpine is likewise formed when the hydrate is dried over sulphuric acid. Anhydrous terpine (cis-terpine) melts at 102° or at 104° to 105°, according to its purity. It is very hygroscopic. It be- haves as a saturated compound, being readily converted into dipentene dihydrochloride or dihydrobromide on treatment with phosphorus trichloride or tribromide ; the halogen hydrides also react with terpine, forming the corresponding dipentene addition- products. It has already been noted under the derivatives of dipentene that the above suggested reactions yield a mixture of the eis- and trans-isomerides (Baeyer). The behavior of terpine hydrate towards dehydrating agents has frequently been a subject of investigation. It was formerly believed that a homogeneous substance resulted by heating terpine hydrate with dilute acids; Tilden 7 recognized, however, that an oxidized compound, C 10 H 18 O, was formed, together with terpenes, i Wallach, Ann. Chem., 227, 284. »Flawitzky, Ber., 12, 2358. swallach and Kremers, Ann. Chem., 270, 188. Seville, Ann. Chem., 71, 348. sßlanchet and Sell, Ann. Chem., 6, 268. s Wallach, Ann. Chem., 230, 247. i Tilden, Jahresb. Chem., 1878, 639. 21 322 THE TERPENES. C 10 H 16 . Detailed researches regarding this reaction have been made by Wallach. When terpine hydrate is boiled with dilute sulphuric acid (one part of acid to two parts of water), terpinene, terpinolene and ter- pineol are formed ; when a very dilute acid (one volume of sul- phuric acid to seven volumes of water) is used, it yields a product consisting largely of terpinene, with almost no terpineol. If the hydrate be heated with twenty per cent, phosphoric acid, it is changed chiefly into terpineol, while a small quantity of terpino- lene and dipentene, but no terpinene, results. Boiling glacial acetic acid slowly converts terpine hydrate into terpineol ; but when heated with glacial acetic acid in a sealed tube at 190° to 200°, terpinene is the principal product. It is converted into dipentene and terpineol by heating with acid potassium sulphate at 190° to 200°. In all these reactions small quantities of cineole are produced. The elimination of water from terpine hydrate, under all con- ditions, at first yields " terpineol " and a little cineole. It was explained under terpineol that this " terpineol " obtained by Wal- lach by dehydrating terpine hydrate was later found to be a mix- ture. (See page 254.) If ten grams of terpine hydrate are dissolved in twenty grams of cold, colorless, concentrated nitric acid, and the re- sultant clear, rose-colored liquid be very gently warmed, an oil separates which, according to Wallach, 1 is to be regarded as the nitric acid ester of terpine (or terpineol?); when this oil is treated with sodium hydroxide and distilled with steam, it yields some terpine hydrate and products similar to those obtained by the action of other acids on terpine hydrate. A mono-acetyl ester of terpine, C 10 H 19 O(C 2 H 3 O 2 ), was obtained by Oppenheim 2 by heating terpine hydrate with acetic anhydride. It has an odor like that of orange, and boils at 140° to 150° under a pressure of 20 mm. Hexahydrocymene, C 10 H 20 , is formed by the action of concen- trated hydriodic acid on terpine hydrate at 210°. It boils at 168° to 170°, and has the specific gravity of 0.797 at 15° (A. Schtschukarew 3 ). The oxidation of terpine hydrate with nitric acid yields terebic, para-toluic, and terephthalio acids, whilst chromic anhydride converts it into acetic and terpenylic acids (Hempel 4 ). i Wallach, Ann. Chem., 230, 253; 239, 17; compare Bouchardat and Voiry, Compt. rend., 104, 996; 106, 663; Ann. Chim. Phys. [6], 16, 251; Wallach, Ann. Chem., 246, 265; 252, 133. 2 Oppenheim, Ann. Chem., 129, 157. 3 Schtschukarew, Ber., 23, 433, Ref. * Hempel, Ann. Chem., 180, 71. CINEOLE. 323 An aqueous solution of terpine hydrate is not acted on by potassium permanganate at the ordinary temperature, but, on warming, it is resolved into acetic acid, oxalic acid, etc.; terpenylic acid is not formed in this reaction (Tiemann and Schmidt 1 ). Cis-terpine in a hot, glacial acetic acid solution is converted by chromic anhydride into an orange-colored chromium compound, which, on heating with glacial acetic acid, yields terpine hydrate and the keto-lactone, C 10 H 16 O 3 , described by Tiemann and Schmidt as methoethylheptanonolide ; the same keto-lactone was obtained by Wallach in the oxidation of terpineol (m. p. 35°) with potas- sium permanganate. 11. MENTHENE GLYCOL, C 10 H 18 (OH) 2 . Menthene glycol was obtained, together with other substances, by Wagner by the action of potassium permanganate on menthene ; it has been described under menthene. 12. CINEOLE, C 10 H 18 O. Cineole is a widely distributed constituent of many ethereal oils. It was first characterized as a chemical individual and called cineole by Wallach and Brass, 2 who separated it in a condition of purity from oil of levant wormseed, by means of its hydrochloric acid derivative. A compound having the formula, C 10 H 18 O, had already been detected in wormseed oil by earlier investigators, but had never been isolated in a pure condition. Simultaneous with the recognition of cineole in wormseed oil, Wallach 3 showed that it is identical with the oxidized constituent of oil of cajeput, which was formerly called " cajeputol." Cineole was then found in various ethereal oils, among which may be mentioned oil of rosemary, in which cineole was discovered by Weber, 4 in eucalyptus oil by Jahns 5 and by Wallach and Gilde- meister, 6 in oil of sage, laurel leaf oil and laurel berry oil by Wallach. 7 It also occurs in the oil of cheken-leaves, galangal iTiemann and Schmidt, Ber., 28, 1781. 2 Wallach and Brass, Ann. Chem., 225, 291. aWallach, Ann. Chem., 225, 315. C=CH— CH— CH— CO— CH 3 CHs Methyl hexylene ketone. 'For more retcent formulas of cineole and cineolic acid, see Wallach, Ann. Chem., 291 , 350. 330 THE TEBPENES. Methyl hexylene ketone (methyl heptenone), C 8 H u O, is a liquid, having an agreeable odor like that of amyl acetate ; it boils at 173° to 174°, has a refractive power, n c = 1.44003, and specific gravity of 0.8530 at 20°. According to Schimmel & Co., it boils at 170° to 171° (758 mm.), has the sp. gr. 0.858 and re- fractive index, n^ = 1.44388, at 15°. It unites readily with bromine, and is decomposed by permanganate. It does not decolorize a sulphurous acid solution of fuchsine, but forms an unstable additive compound with acid sodium sulphite, and com- bines with Phenylhydrazine and hydroxylamine, yielding an oily hydrazoneand oxime. Its semicarbazone 1 melts at 136° to 138°. Meta-dihydroxylene, C g H 12 , is formed, together with a poly- meride of this hydrocarbon, when methyl hexylene ketone is heated with zinc chloride at 90° to 95°. This transformation is probably expressed by the following equation : Methyl hexylene ketone. Meta-dihydroxylene. When meta-dihydroxylene is carefully treated with nitric acid, it yields nitro-m-xylene. Methyl hexylene ketone has recently become quite important in consequence of its discovery in many ethereal oils, and because of its relation to the aliphatic members of the terpene series. Its constitution is completely explained by the researches of Tiemann and Semmler, who made the important observation that methyl heptenone is converted into acetone and laevulinic acid by oxidation. For the various syntheses and methods of preparation of methyl heptenone, and an enumeration of its derivatives, the original publications 2 must be consulted. An unsaturated alcohol, 3 methyl heptenol (methyl hexylene car- binol), C 8 H 15 OH, is formed, when methyl hexylene ketone is re- T Tiemann and Krüger, Ber., 28, 2124. *L6ser, Bull. Soc. Chim., 17 [III.], 108; Compt. rend., 127, 763; 128, 108; Barbier and Bouveault, Compt. rend., 121, 168; 122, 393 and 1422; Bar- bier and Leser, Bull. Soc. Chim., 17 [III.], 748; Barbier, Compt. rend., 128, 110; Verley, Bull. Soc. Chim., 17 [III.], 175; Tiemann, Ber., 31, 2989; 32, 812 and 830; Tiemann and Semmler, Ber., 26, 2719 and 2721; 28, 2128; Wallach, Ann. Chem., 319, 77. ^Wallach, Ann. Chem., 275, 171. METHYL HEXYLENE OXIDE. 331 duced with sodium and alcohol. This alcohol is also obtained as a decomposition product of geraniol, and further by the hydrol- ysis of geranic nitrile. It boils at 174° to 176°, has a sp. gr. of 0.850 and a refractive index, n^ = 1.44889. When this alcohol is boiled with dilute sulphuric acid, it is converted into an isomeric, saturated oxide, C 8 H lg O. This reaction is quite analogous to that by which the homologous alcohol, C 9 H 17 OH, obtained from methyl heptylene ketone, is converted into an isomeric oxide, C 9 H lg O (see thujone). Methyl hexylene oxide, C g H 16 0, boils at 127° to 129°, has a specific gravity of 0.850 and index of refraction, n^ = 1.4249. It has an odor resembling that of peppermiut and of cineole, and is probably a homologue of the oxide, boiling at 78° to 83°, which Perkin and Freer 1 obtained from f-pentylene glycol. CH,— CH— CH, CH 3 CH(OH) CH 3 CH s CH J (OH)=H 3 0+ 0<^ CH, — CH, y-Pentylene glycol. y-Pentylene oxide. QH, \r,Fr— r CH >CH— CH- a yi /C=CH — CH, — CH, — CH ( OH ) — CH 3 = 0< / CH CH,— CH— CH, Methyl hexylene oxide. Methyl hexylene carbinol. Wallach and Elkeles also prepared methyl hexylene ketone by the distillation of cineolic amides : — /CONHE C 8 H u O< =RNH,+CO+CO,+C 8 H u O. \COOH When cineolic acid is submitted to dry distillation, it is par- tially converted into its anhydride, and partially into a liquid monobasic acid, C 9 H 16 0 3 (b. p. 135° under 11 mm.), together with some methyl hexylene ketone : 2 — C 10 H 16 O 5 = C0 2 + C 9 H 16 0 3 . Wallach and Elkeles have described the methyl ester of this monobasic acid, C 9 H 16 0 3 ; it is a liquid, boiling at 125° under a pressure of 13 mm. Wallach and Gildemeister obtained only oxalic acid and carbon dioxide by the oxidation of cineolic acid with permanganate or dilute nitric acid. These two products are also formed when cineole is oxidized with dilute nitric acid ; therefore, a relation- ship between cineolic acid and terebic acid or terpenylic acid does not appear to exist. i Perkin and Freer, Ber., 19, 2568; compare Lipp, Ber., 18, 3285; 19, 2843. 2 Wallach, Ann. Chem., 246, 274; 258, 321; 271, 26; Rupe, Ber., 38, 1129. 332 THE TERPENES. According to Kupe, 1 when cineolic acid is heated with water at 160° for three hours, it yields a mixture of two isomeric acids, C 9 H 16 0 3 ; one of these acids is termed a-cinenic acid, and the other is called methoethylol-5-hexene-2-acid-6. a-Cinenic acid, C 9 H 16 0 3 , is stable towards potassium permanga- nate, is not acted upon by bromine, does not react with phenyl- hydrazine, hydroxylamine, or semicarbazide, and probably contains a cyclic arrangement of the carbon atoms. It is a monobasic acid, crystallizes from petroleum ether in transparent crystals, melts at 83° to 84°, and boils at 127.5° to 129.5° (14 mm.) or at 245° to 247° under atmospheric pressure. It is soluble in most organic solvents, readily soluble in hot, sparingly in cold, water ; it is volatile with steam. It forms silver and calcium salts, and methyl and ethyl esters. When a-cinenic acid is heated with water in a closed tube at 160°, it is partially converted into methoethylol- 5-hexene-2-acid-6. When hydrochloric acid gas is allowed to act upon the alcoholic solution of a-cinenic acid, without cooling, ethyl-d-chloro-a-methoethylol-5-hexoate, C 8 H 15 Cl(OH)'COOC 2 H 5 , is formed; this ester boils at 131° to 136° (17 mm.), and is an open-chain compound. When a-cinenic acid is treated with a glacial acetic acid solu- tion of hydrogen bromide, it yields d-bromo-a-oxyisopropyl hexe- noic acid, C 8 H 15 Br(OH)-COOH, which crystallizes in needles and melts at 97° to 98° ; when the latter acid is treated with alcoholic potash, it gives rise to methoethylol-5-hexene-2-acid-6, and when treated with water, it forms cinogenic acid, C 8 H 15 (OH) 2 -COOH. Cinogenic acid (o'-oxy-a-oxyisopropyl hexenoic acid) is also one of the products of the action of water under pressure on cineolic acid ; it is insoluble in ether, crystallizes from chloroform in tablets and meltsat 104.5° to 105°; when distilled under diminished pres- sure, or heated under pressure with water, it yields a-cinenic acid. /9-Cinenic acid, C 9 H 16 O a , is formed by the action of sulphuric acid on cineolic acid, and also by heating a-cinenic acid with dilute sulphuric acid under pressure ; it is stereoisomeric with a-cinenic acid, and is possibly an example of eis- and trans-iso- merism. It is a liquid acid, boiling at 122° to 123° (10 mm.), has the refractive index, n^ = 1.4486, and forms a characteristic calcium salt, which crystallizes from water in needles ; the corre- sponding salt of a-cinenic acid is amorphous. /3-Cinenic acid may be converted into cinogenic acid in the same manner as the a-acid. Methoethylol-5-hexene-2-acid-6 (a-oxyisopropyl-J^-hexenoic acid), C 9 H le O 3 , is isomeric with the cinenic acids and is formed together with a-cinenic acid by the action of water on cineolic acid. iRupe, Chem. Centr., 1898 [II.], 1055; Ber., 33, 1129; 34, 2191. D- AND L-CINEOLIC ACIDS. 333 It crystallizes from water in small leaflets and from petroleum in silky needles; it melts at 59° to 60°, and boils at 152° to 153° (10 mm.). It decolorizes aqueous permanganate solutions, com- bines directly with one molecule of bromine, and contains an open-chain of carbon atoms. It is much more soluble in water than a-cinenic acid, and forms silver and magnesium salts. This acid is a /3-oxy-acid, and when distilled under atmospheric pres- sure, it loses one molecule of water, yielding a-iso-propylidene- Jv-hexenoie acid (methoethene-5-hexene-£-acid-6), C 9 H 14 O z ; this is a colorless, liquid acid, which boils at 136° to 138° (11 mm.), has the sp. gr. 0.9816 at 17°, and gradually resinifies in the air. By means of the strychnine salt, Rupe and Eonus 1 have re- solved cineolic acid into its optically active components. When cineolic acid is dissolved in hot water and is treated with one molecular weight of finely pulverized strychnine, the salts of the two optically active and the inactive acids are obtained ; they are separated by fractional crystallization. The strychnine salt of dextro-cineolic acid, C 31 H 36 0 6 N 2 , separates first and may be re- crystallized from hot water ; it forms large prisms, which melt at 195° to 197°. On further evaporation, the mother-liquors of the dextro-salt yield successively the salts of the inactive and levo- cineolic acids. The strychnine salts of the active cineolic acids are converted into the free acids by treatment with dilute hydrochloric acid at a temperature not exceeding 40°. The resulting dextro- and levo- cineolic acids are repeatedly crystallized from water in order to free them (especially the levo-acid) from admixed racemic cineolic acid. The optically active acids, C 10 H 16 O 5 + H z O, separate from water in large, transparent crystals which contain one molecule of water of crystallization, and melt at 79° ; the racemic acid never crystallizes with water of crystallization, and is formed by crystal- lizing a mixture of equal quantities of the two optically active acids. When the hydrated crystals of the active acids are exposed to dry air, they lose their water, yielding anhydrous acids which melt at 138° to 139°, and have the specific rotatory powers, \a\ D = + 18.56° and — 19.10°. The racemic acid melts 2 at 204° to 206°. The active acids are much more soluble in water and in chloro- form than the racemic acid. On dry distillation they yield the anhydride, methyl heptenone and other decomposition products. !Rupe and Ronus, Ber., 33, 3541. 2 According to Wallach and Gildemeister, the inactive acid melta at 196" to 197°. 334 THE TERPENES. d-Cineolic anhydride, C 10 H u O 4 , is formed by the action of acetic anhydride on d-cineolic acid; it boils at 165° to 167° (15 mm.), dissolves sparingly in petroleum ether, and crystallizes from benzene in large tablets, melting at 108°. It has the specific rotatory power, [a]^ = + 45.37°, at 20° in a benzene solution. 13. TERPAN-1, 4, 8-TRIOL, C 10 H 17 (OH) 3 . This compound has already been mentioned as an oxidation product of Baeyer's J 4(8) terpen-l-ol (see page 273). Its con- stitution may be regarded as proved by its transformation into tribromoterpane, melting at 110°. 14. TRIOXYHEXAHYDROCYMENE, C 10 H 17 (OH) 3 . This substance melts at 121° to 122°. (Compare under ter- pineol, page 262.) 15. PINOLE HYDRATE, C 10 H 17 OOH. This compound is described under pinole ; see page 276. 16. LIMONETROL, C 10 H 16 (OH) 4 . Limonetrol is prepared by the following method suggested by G. Wagner. 1 Five liters of a one per cent, solution of permanganate are added drop by drop to a mixture of one liter of water and sixty- five grams of limonene, the mixture being continually shaken. When the reaction is complete, the product is filtered and the precipitate, consisting of manganese oxides, is carefully washed with water. The volatile compounds are removed from the fil- trate by distillation with steam, and the residue is concentrated by evaporation and extracted with ether. On evaporation of this solvent, the resultant limonetrol is washed with a small quantity of ether, and crystallized from alcohol ; it separates in small, lustrous needles. The yield is very good. This tetrahydric alcohol is readily soluble in water, has a sweet taste, and melts at 191.5° to 192°. 17. PINOLE GLYCOLS, C 10 H 16 O(OH) 2 . These compounds are mentioned under pinole (see page 279). The most important transformations of the various keto- and oxy-hydrocymenes, in so far as they are not represented in the tables given under terpineol, are shown in the accompanying table. iG. Wagner, Ber., 2S, 2315. KETO- AND OXY-HYDROCYMENES ; TABLE OF. 335 AMIDO-DERIVATIVES OF THE TERPENES. I. BASES WHICH CAN NOT BE REGARDED AS DE- RIVATIVES OF THE HYDROCYMENES. (Analogues of Pinene, Camphene, Fenchene, and of Cam- pholenic Acid and Fencholenic Acid. 1 ) 1. PIN YL AMINE, C 10 H 15 NH 2 . Pinylamine is formed by the reduction of nitrosopinene, the compound obtained by the action of alcoholic potash on pinene nitrosochloride : — C 10 H 15 NO + 4H = H,0 + C 10 H 1S NH,. In order to prepare it, thirty grams of nitrosopinene are dis- solved in about 200 cc. of warm glacial acetic acid ; the solution is diluted with water until it commences to appear cloudy, and is then treated with zinc dust, which is added in small portions at a time. After the first violent evolution of hydrogen has abated, the reaction is accelerated by adding water and heating the mix- ture on the water-bath for several hours. The liquid is then poured off from the zinc, which must always be present in excess, and is diluted with a large amount of water ; the zinc is precipi- tated from the hot solution by hydrogen sulphide, is filtered off, and the filtrate concentrated on the water-bath until a dark coloration appears. It is again filtered, and the sparingly soluble pinylamine nitrate is precipitated by the addition of a hot, satur- ated solution of sodium nitrate. It is crystallized from hot water. The yield of pinylamine is approximately fifty per cent, of the theoretical (Wallach and Lorentz 2 ). The free base is produced by treating pinylamine nitrate with sodium hydroxide ; it is dried over potash, and distilled in vacuum. l A series of papers has been published by P. Duden on "Synthetical bases of the series of terpenes and camphors " ; the following references are men- tioned: Ber., 33, 481; Ann. Chem., 313, 25 and 59. 2 Wallach and Lorentz, Ann. Chem., 268, 197; compare Ann. Chem., 258, 346, and Ber., 24, 1549. 336 ACETYL PINYLAMINE. 337 When freshly distilled, it is a thick, colorless oil, which boils at 207° to 208° under ordinary pressure, and at 98° to 99° under 22 mm. to 23 mm. It may be kept unchanged in a sealed vessel, but in the air it soon decomposes with liberation of ammonia ; it also takes up carbonic anhydride from the air. It is almost in- soluble in water, but dissolves freely in alcohol, ether and chloro- form. It has a strong basic smell, resembling that of borneol. Its specific gravity at 17° is 0.943. Pinylamine is an unsaturated compound. Pinylamine hydrochloride, C 10 H 15 NH 2 *HC1, is precipitated from an ethereal solution of the amine by hydrochloric acid gas, and crystallizes from water in thin needles, melting at 229° to 230°. If this salt be heated above its melting point, it is very readily decomposed into ammonium chloride, cymene, and a small quantity of a compound which appears to unite with oxygen in the air, and has the composition, C ]0 H 16 O ; this oxygenated com- pound yields an oxime when treated with hydroxylamine. The decomposition of pinylamine hydrochloride is represented by the equation :— C 10 H 15 NH 2 -HC1 = NH 4 C1 + C 10 H I4 . Pinylamine platinochloride, (C 10 H 17 N-HCl) 2 PtCl 4 , is sparingly soluble in water, but freely in alcohol; it decomposes without melting when heated above 200°. Pinylamine nitrate, C 10 H 15 NH 2 -HNO 3 , is difficultly soluble in water. It crystallizes from dilute alcohol in long, colorless needles. Pinylamine sulphate, (C^H^NH^-H.SO^ forms small needles, and decomposes above 200° without melting. Pinylamine thiocyanate, C 10 H 15 NH 2 HCNS, is obtained, when the aqueous solutions of equal molecular proportions of pinylamine hydrochloride and potassium thiocyanate are mixed, allowed to evaporate, and the residue is extracted with alcohol. It crystal- lizes from water in well defined prisms, and melts at 135° to 136°. Pinylamine oxalate, (C 10 H 15 NH 2 ) 2 H 2 C 2 O 4 , separates at once in the form of brilliant crystals, if a concentrated aqueous solution of one molecular proportion of oxalic acid be added to a dilute alcoholic solution of two molecules of pinylamine. It melts without decomposition at 247° to 248°, and dissolves sparingly in all ordinary solvents. Pinylamine picrate forms yellow needles, and is slightly soluble in cold water. Acetyl pinylamine, C 10 H 15 NHCOCH 3 , is prepared by heating pinylamine with acetic anhydride. It crystallizes from petroleum ether or alcohol, and melts at 108° to 109°. 22 338 THE TERPENES. Benzoyl pinylamine, C 10 H 15 NHCOC 6 H 5 , is best obtained by the action of one molecule of benzoyl chloride on an ethereal solution of two molecular proportions of pinylamine; some pinylamine hydrochloride separates during the reaction, and is filtered off. The ethereal solution is evaporated, and the resulting benzoyl compound is washed with ammonia, and crystallized from glacial acetic acid or petroleum ether; it separates in small needles, melting at 125°. Piny 1 carbamide, C 10 H 15 NHCONH 2 , is produced by treating pinylamine hydrochloride with potassium cyanate ; it crystallizes in long, colorless needles, and melts at 156°. Benzylidene pinylamine, C 10 H 18 N = CH-C 6 H 5 , results on mixing equal molecular weights of pinylamine and benzaldehyde ; the mixture becomes warm, and the reaction takes place with elimina- tion of water. It crystallizes from alcohol in splendid crystals, melts at 52° to 53°, and decomposes on keeping. Furfuro-pinylamine, C 10 H 15 N = CHC 4 H 3 0, is the condensation- product of pinylamine and furfural ; it separates from alcohol in well formed crystals, and melts at 80° to 81°. o-Oxybenzylidene pinylamine, C 10 H ]6 N == CH C 6 H 4 OH, forms lustrous, yellow crystals, and melts at i08° to 109°. The halogen alky Is react vigorously with pinylamine. Pinocarveol, 1 C 10 H 15 OH, is formed when pinylamine is heated with a solution of sodium nitrite. Since this is a secondary alcohol, the following formula of pinylamine, originally proposed by Wallach, does not represent the facts : H 8 C CH S 2. AMIDOTEREBENTENE, C 10 H 15 NH 2 . Pesci and Betelli 2 also converted pinene into an amine, Ci 0 H 15 NH 2 , which is isomeric with pinylamine. It is obtained from nitroterebentene. 'Wallach, Ann. Chem., 277, 149; Wallach and Smythe, Ann. Chem., 800, 286. aPesci and Betelli, Gazz. Chim., 16, 337; Jahresb. Chem., 1886, 613. PINENE PHTHALAMIC ACID. 339 Nitroterebentene, C 10 H 16 NO 2 , is obtained by treating French or American 1 oil of turpentine (levo- or dextro-pinene) with nitrous acid. A seventy-five per cent, aqueous solution of 135 parts of potassium nitrite is gradually added to a cold mixture of 100 parts of the terpene and 545 parts of dilute sulphuric acid (145 parts of concentrated acid to 400 parts of water), the mixture being well shaken ; a green oil is formed, and is separated by the addition of an excess of water. This product is shaken with ammonia, and purified by fractional distillation with steam (Pesci and Betelli 2 ). It is a yellow liquid, having an odor of peppermint, and is readily decomposed on heating. Amidoterebentene is prepared by reducing nitroterebentene with zinc dust and glacial acetic acid. It is an oil, having an agree- able odor, and boils at 197° to 200°, undergoing slight decom- position ; it boils without decomposition at 94° to 97° under a pressure of 9 mm. (Pesci and Betelli). Amidoterebentene hydrochloride, C 10 H 15 NH 2 - HCl, obtained from either levo- or dextro-pinene, is optically levorotatory, 1 [a] D = — 48.5°. It crystallizes in rectangular tablets, having a mother-of- pearl luster. The platinum salt forms hexagonal plates, is insoluble in cold water, and is decomposed by boiling water. The sulphate separates in a gelatinous, hygroscopic mass. The oxalate is ob- tained in sparingly soluble leaflets. Pinene phthalimide, C 6 H 4 < >NC 10 H 15 prepared by Pesci 3 by the action of phthalic anhydride on amido- terebentene, melts at 99° to 100°. It is insoluble in water, read- ily soluble in alcohol, ether, and chloroform, and has the specific rotatory power, [a] D — — 35.38°. The potassium salt of pinene phthalamic acid is formed by dissolving pinene phthalimide in a hot solution of potash ; it crystallizes in thin needles. Pinene phthalamic acid, /COOH c 6 h/ x conhc io h 15 results by decomposing its potassium salt with hydrochloric acid. ' Pesci, Gazz. Chim., 18, 219; Jahresb. Chem., 1888, 899. 2Pesci and Betelli, Gazz. Chim., 16, 337; Jahresb. Chem., 1886, 613. "Pesci, Gazz. Chim., 21 (I.), 1; Chem. Centr., 1891 (I.), 542. 340 THE TERPENES. It is recrystallized from chloroform, melts at 109° to 111 0 , and is very unstable. Trimethyl terebenthyl ammonium iodide, C 10 H 15 N(CH 3 ) 3 I, is pro- duced by the interaction of methyl iodide and amidoterebentene, and crystallizes in rectangular leaflets. The chloride, prepared from the iodide, is deliquescent, but yields a platinum salt which is nearly insoluble (Pesci and Betelli). 3. BORNYLAMINES, C 10 H 17 NH 2 . Bornylamine was discovered by Leuckart and Bach, 1 who ob- tained it by the treatment of camphor with ammonium formate, and also by the reduction of camphoroxime with sodium and alco- hol. It was later made the subject of a detailed investigation by Wallach and Griepenkerl. 2 It is best prepared by the method proposed by Leuckart and Bach and subsequently modified by Wallach and Griepenkerl. An intimate mixture of not more than four grams of camphor and the same weight of ammonium formate is heated at 220° to 230° for five hours. The reaction-product forms a syrupy mass consisting chiefly of formyl bornylamine, together with some free bornylamine, unchanged camphor, and ammonium salts, and solidi- fies when shaken with cold water. It is boiled with alcoholic potash for five or six hours, and the resulting bornylamine and camphor are distilled over with steam. The distillate is acidified with hydrochloric acid, filtered, concentrated and shaken with ether to remove impurities which may be present in the solution. The base is then set free by potash, extracted with ether, and the ethereal solution dried with potassium hydroxide ; the ether is dis- tilled off, and the bornylamine rectified, being careful to keep the receiver well cooled on account of the extreme volatility of the base. The yield is about eighty to eighty-two per cent. Bornylamine melts at 159° to 160°, boils at 199° to 200°, and dissolves very easily in alcohol and ether. It has an intensive basic odor resembling that of camphor and piperidine ; it sublimes at the ordinary temperature, and unites readily with carbonic anhydride in the air. It is optically active, a 12.5 per cent, solu- tion having a specific rotatory power of \a\ D — — 18° 35' 41" (Leuckart and Bach). Bornylamine hydrochloride, C 10 H 17 NH 2 -HC1, is precipitated in the form of small, white needles when hydrogen chloride is passed into an ethereal solution of bornylamine. When the hydrochloride "Leuckart and Bach, Ber., 20, 104. 2 Wallach and Griepenkerl, Ann. Chem., 269, 347. BENZOYL BORNYLAMINE. 341 is dissolved in water or alcohol, it suffers partial decomposition. It sublimes undecomposed in splendid needles without the forma- tion of ammonium chloride and camphor. The platinochloride, (C 10 H 17 NH 2 -HCl) 2 PtCl 4 , dissolves readily in hot water and alcohol, and forms golden-yellow scales. Bornylamine hydrobromide, 1 C 10 H 17 NH 2 -HBr, separates as a colorless, crystalline precipitate on the addition of bromine to an ethereal bornylamine solution. It combines with bromine, form- ing an unstable, red product. Bornylamine acid sulphate, 2 C 10 H 17 NH 2 -H 2 SO 4 , is prepared from the theoretical quantities of dilute sulphuric acid and bornylamine ; it separates in orthorhombic tablets on evaporation of the solution. Like the hydrochloride, its aqueous solution is decomposed by boiling. Bornylamine tartrate, C 10 H 17 NH 2 C 4 H 6 O 4 + H 2 0, is easily solu- ble in water, almost insoluble in cold alcohol, and crystallizes from hot alcohol in needles. Bornylamine picrate, 1 C 10 H 17 NH 2 C 6 H 2 (NO 2 ) 3 OH, forms golden- yellow needles, which are almost insoluble in ether. Bornylamine is very readily converted into the carbylamine de- rivative. 2 When bornylamine or its formyl compound is heated at 200° to 210° with acetic anhydride, it is decomposed into camphene, C 10 H 16 , and ammonia : 1 C 10 H 17 NH 2 = C 10 H 16 + NH 3 . Formyl bornylamine, 2 C, 0 H 17 NH-CHO. — It has already been mentioned that this compound forms the chief constituent of the reaction-product produced by the action of ammonium formate on camphor ; it may also be prepared by the action of formic acid on the free base. When recrystallized from hot water, it forms white, glistening scales, melting at 61°. Acetyl bornylamine, 2 C 10 H 17 NH-COCH 3 , is formed by the action of acetyl chloride on an ethereal solution of bornylamine ; the bornylamine hydrochloride, which at first separates, is filtered off, the ethereal filtrate evaporated, and the resultant acetyl compound crystallized from dilute alcohol. It forms leaflets, melting at 1 41 °, and is nearly insoluble in ligroine. Benzoyl bornylamine, C 10 H 17 NHCOC 6 H 5 , is prepared like the preceding compound, and is similar to it in appearance and solu- bility. It melts at 131°. i Wallach and Griepenkerl, Ann. Cliera., 261), 347. 2Leuckart and Bach, Ber., 20, 104. 342 THE TERPENES. Bornylcarbamide, 1 C 10 H 17 NH-CO-NH 2 , is formed from bornyl- amine hydrochloride and potassium isocyanate. It crystallizes in needles, which melt at 164°, and is readily soluble in hot water and alcohol. Methyl bornylcarbamide, 1 C 10 H 17 NHCONHCH 3 , results by mixing the ethereal solutions of methyl isocyanate and bornyl- amine. It melts at 200°. Phenyl bornylcarbamide, 1 C 10 H 17 NH-CONHC 6 H 5 , separates in the form of silvery leaflets when phenyl isocyanate is added to an ethereal solution of bornylamine. It melts and decomposes at 248°. Bornyl phenylthiocarbamide, 1 C 10 H 17 NHCSNHC 6 H 5 , is pro- duced from phenylthiocarbimide and the free base in an ethereal solution ; it forms colorless needles, which melt at 170° and are almost insoluble in petroleum ether. Dibornylthiocarbamide, 2 CS(NHC 10 H 17 ) 2 , is formed when the dithiocarbamic acid salt, obtained by the interaction of carbon bisulphide and bornylamine, is boiled for some time with ten to fifteen times its weight of ninety-six per cent, alcohol. It sepa- rates from alcohol in compact, transparent crystals, which melt at 223° to 224°. According to Wallach and Griepenkerl, 2 the alkyl chlorides act vigorously on bornylamine. When equal molecular quantities of benzyl chloride and the free amine are heated at 140° to 150° and the resulting product is treated with alkalis, a mixture of bases is obtained which is fractionally distilled in vacuum ; the following compound is thus isolated. Benzyl bornylamine, C 10 H 17 NH-CH 2 C 6 H 5 , is a thick oil, boiling at 184° under 14 mm. pressure. The hydrochloric acid salt separates from water or alcohol in colorless crystals ; its platino- chloride crystallizes in red, transparent prisms. Benzyl bornylamine unites with methyl iodide, forming a meth- iodide, which crystallizes from hot alcohol in thin needles, and is very difficultly soluble in hot water. Benzylidene bornylamine, 2 C ]0 H 17 N = CHC 6 H 5 , is an oil ; its hydrochloride, which crystallizes in small needles, and its platino- chloride have been analyzed. The other condensation-products of bornylamine with aldehydes are liquids. Bornylamine is very stable towards fuming nitric acid (Wal- lach and Griepenkerl 2 ). JLeuckart and Bach, Ber., 20, 104. ^Wallach and Griepenkerl, Ann. Chem., 269, 347. DIBORNYLAMINE NITRITE. 343 When formyl bornylamine is oxidized with an acetic acid solu- tion of chromic anhydride, it yields bornylaraine and small quan- tities of a very volatile compound, which melts at 159°, and con- tains oxygen but no nitrogen ; it appears to have the empirical formula, C 10 H 16 O or C 10 H lg O. A compound having the same melting point has also been observed by Lampe 1 in the decompo- sition of bornylaraine nitrite. Dibornylamine, (C 10 H 17 ) 2 NH, is obtained in a yield of about nine per cent, from the product of the action between camphor and ammonium formate (Wallach and Griepenkerl 2 ). It remains in the residue from the distillation of bornylaraine with steam, and is obtained as an oil which slowly solidifies j it may be puri- fied by distillation in vacuum. Dibornylamine boils at 180° to 181° under a pressure of 12 mm., and crystallizes from alcohol in lustrous plates, melting at 43° to 44°/ Dibornylamine hydrochloride, C 20 H 35 N-HC1, is precipitated by passing hydrochloric acid gas into an ethereal solution of the base. It crystallizes in needles or plates, dissolves sparingly in cold, readily in hot, water and melts at 260° with partial decom- position. Its platinochloride crystallizes in red needles. Dibornylamine nitrate, C 20 H 35 NHNO 3 , is sparingly soluble in water ; it is well adapted for the separation of dibornylamine from bornylamine. A compound, C 2 H 35 N HBrBr 2 , is formed when bromine is added to a solution of dibornylamine in petroleum ether. It is almost insoluble in ether and ethyl acetate, but crystallizes from alcohol in stable, golden-yellow plates, which melt at 184°. Dibornylamine nitrite, C 20 H 3R N-HNO 2 , is rather sparingly soluble in water, but may be recrystallized unchanged from boiling alcohol. On boiling with acetic anhydride, dibornylamine forms a com- pound, which crystallizes from alcohol in lustrous plates, melts at 59°, and seems to be isomeric with dibornylamine. According to more recent investigations by Forster, 3 the bornyl- amine prepared by heating camphor with ammonium formate at 220° to 240° or by reducing camphoroxime with sodium and amyl alcohol is not an individual compound, but contains two isomeric bases, C 10 H 17 NH 2 . One of these melts at 163°, is dextrorotatory, [a] D = + 45.5°, and is termed bornylamine, whilst the other melts at 180°, is levorotatory, [a\ D = — 31.3°, and is ^ampe, Inaug. Diss., Göttingen, 1889, 41. 2 Wallach and Griepenkerl, Ann. Chem., 269, 347. a Martin O. Forster, Journ. Chem. Soc, 73, 386; 75, 934 and 1149. 344 THE TERPENES. called neobornylamine. (Leuckart and Bach's " bornylamine " melts at 159° to 160°, and is levorotatory, [fi\ D = — 18.6°.) Although bornylamine melts lower than neobornylamine, all its derivatives possess a higher melting point than those of the isomeride. The derivatives of bornylamine are also less readily soluble than those of the levorotatory base, and this property is employed in effecting the separation of the two iso- merides. The preparation of the two isomerides is accomplished as fol- lows. Seventy-five grams of camphoroxime, dissolved in 750 cc. of amyl alcohol, are treated in a reflux apparatus with seventy- five grams of sodium ; the process requires about four hours, after which 100 cc. of amyl alcohol are added. The reaction-mixture is then treated with 450 cc. of water, and the same volume of concentrated hydrochloric acid; the amyl alcohol is finally re- moved by distillation with steam, and on allowing the aqueous residue to cool, the hydrochlorides of the two amines crystallize rapidly in lustrous needles. The yield is practically quanti- tative. The separation of the two isomeric bases is based on the greater solubility in water of the hydrochloride of neobornylamine. The free bases are obtained by decomposing the hydrochlorides with caustic soda. About sixty per cent, of the product obtained on reducing camphoroxime as above described consists of the dextro- rotatory bornylamine, and forty per cent, is the levo-neobornyl- amine. Bornylamine, C 10 H 17 NH 2 , is a white volatile solid, melting at 163°; it somewhat resembles camphor, having a faint, pungent odor like that of piperidine. It dissolves very readily in cold organic solvents, but is insoluble in water (Förster). Neobornylamine, C 10 H 17 NH 2 , closely resembles its isomeride, but remains as a powder after being kept in a desiccator, which treat- ment causes bornylamine to become more camphor-like in con- sistence ; it melts at 180°. It is insoluble in water, but more freely soluble in organic solvents than bornylamine. Many derivatives of the two bases have been prepared and carefully studied by Forster. The most important of these are given in the accompanying table, which shows the differences in melting points of the derivatives of Forster's bornylamine and neobornylamine, and Leuckart and Bach's bornylamine; the latter may be regarded as a mixture of neobornylamine with about twenty per cent, of the dextro-bornylamine. For the "influence of substitution on specific rotation in the bornylamine series," and the "influence of an unsaturated link- DERIVATIVES OF BORNYLAMINE ; TABLE OF. 345 ing on the optical activity of certain derivatives of bornylamine," the original publications 1 must be consulted. aas Tt< 00 CO -f i-l ■<»>; «5 a^g-Sj^l^ £ c ö § >. >• C C pq a <; pq pu, o &h pn § cd pq cq 'Martin O. Forster, Journ. Chem. Soc, 75, 934 and 1149. 346 THE TERPENES. 4. CAMPHYL AMINES , C g H ls CH 2 NH 2 . a-Camphylamine is produced by the reduction of the nitrile of a-carnpholenic acid (camphoroxime anhydride) : — C 9 H 15 CN+4H=C 9 H 15 CH 2 NH 2 . The reduction may be accomplished by zinc and alcoholic hy- drochloric acid (Goldschmidt and KorefF 1 ), or by sodium and alcohol (Goldschmidt 2 ). Goldschmidt and Schulhof, 3 who made a special study of carnphylamine, employed the last-mentioned method for its preparation. a-Camphylamine 4 is a colorless liquid, boiling at 194° to 196°, and has a strong basic odor; when exposed to the air, it combines with carbon dioxide and solidifies to a waxy mass. In a one decimeter tube, [a]^^ -f 6°. a-Camphylamine hydrochloride, 1 C, 0 H 19 N-HC1, forms colorless, thin, orthorhombic plates ; it is readily soluble. a-Camphylamine platinochloride, 3 (C 10 H 19 N) 2 H 2 PtCl 6 , crystallizes in brilliant, yellow leaflets, which decompose without melting when heated above 200°. The mercuriochloride 2 forms lustrous, ortho- rhombic plates. Acid a-camphylamine oxalate, C 10 H 19 NC 2 O 4 H 2 + iH 2 O, is pre- cipitated when a solution of camphylamine hydrochloride is treated with a solution of oxalic acid ; it separates in colorless, lustrous, orthorhombic crystals, and melts with decomposition at 194°. a-Camphylamine sulphate, (C 10 H 19 N) 2 H 2 SO 4 + H 2 0, crystallizes in orthorhombic prisms, which are readily soluble. It cannot be recrystallized from hot water without decomposition. a-Camphylamine dichromate, (C 10 H 19 N) 2 H 2 Cr 2 O is precipitated from a solution of camphylamine hydrochloride by potassium dichromate. a-Camphylamine picrate forms slender, yellow needles, and melts with decomposition at 194°. Benzoyl a-camphylamine, C 10 H 17 NH-COC 6 H 6 , is obtained when an ethereal solution of camphylamine is treated with benzoyl chloride. Some camphylamine hydrochloride separates and is filtered off; the ethereal filtrate is evaporated, and the residue consisting of the benzoyl compound is washed with a soda solution, 'Goldschmidt and Koreff, Ber., 18, 1632. 2 Goldschmidt, Ber., 18, 3297. "Goldschmidt and Schulhof, Ber., 19, 708. «Tiemann, Ber., 29, 3006. FENCHYLAMINE. 347 and crystallized from ligroine. It separates in colorless prisms, melting at 75° to 77°. a-Campbyl phenylthiocarbamide, C 10 H 17 NH-CSNHC 6 II 5 , is pre- pared by the action of phenylthiocarbimide on an ethereal solution of the base ; it is crystallized from ligroine, and recrystallized from ether. It separates in compact, colorless, lustrous prisms, melts at 118°, and is readily soluble in alcohol and benzene, more sparingly in ether, and very difficultly in ligroine. a-Camphylamine dithiocampbylcarbamate, 1 C 10 H 17 NH-CS-SNH 3 -- C 10 H 17 , is obtained by the action of carbon bisulphide on cam- phylamine. a-Campbyl tbiocarbimide 2 is formed in small quantity when the preceding compound is boiled with a solution of mercuric chloride. a-Camphylamine reacts with ethyl iodide even in the cold, and, like bornylamine, it gives the isonitrile reaction. /3-Campbylamine, 2 C 10 H 17 NH 2 , is produced by the reduction of /2-campholenonitrile, C 9 H 15 CN, in alcoholic solution with sodium. It is optically inactive, and boils at 196° to 198°. 5. FENCHYL AMINE , C 10 H 17 NH 2 . Wallach 3 obtained this compound by treating fenchone with ammonium formate, and also by reducing fenchonoxime with sodium and alcohol. 4 Like fenchone, fenchylamine is known in two optically active modifications having opposite rotatory powers, as well as in an inactive form ; the derivatives of the racemic modification differ from those of its active components in melting point and in solubility. A detailed investigation of dextrorotatory fenchylamine and its derivatives was carried out by Wallach, Griepenkerl and Lührig. 5 In order to prepare fenchylamine by the ammonium formate method, five grams of pure fenchone are heated with an equal weight of ammonium formate at 220° to 230° for six hours. The resultant solid product contains unchanged fenchone, fenchylamine, formyl fenchylamine (the chief product) and ammonium salts. The fenchone is removed by distilling the acidulated reaction- product with steam. The formyl derivative remaining in the residue is saponified by boiling with concentrated hydrochloric i Goldschmidt and Schulhof, Ber., 19, 708. 2Tiemann, Ber., 30, 242. »Wallach, Ann. Chem., 263, 140. 'Wallach, Ann. Chem., 272, 105. 5 Wallach, Griepenkerl and Lührig, Ann. Chem., 269, 358. 348 THE TERPENES. acid, and fenchylamine hydrochloride is obtained on the evapora- tion of the hydrochloric acid solution ; the free base results by decomposing the hydrochloride with potash. The yield of fenchyl- amine is about ninety per cent, of the theoretical. For the preparation of fenchylamine from fenchonoxime, 1 twenty-five grams of sodium are added rather rapidly to a so- lution of twenty-one grams of the oxime in 100 cc. of absolute alcohol. Any undissolved metal is brought into solution by a further addition of alcohol, and the product is then distilled in a current of steam. The resulting amine is dried over potash, and rectified at ordinary pressure. Fenchylamine boils at 195°, and has the specific gravity of 0.9095 at 22° ; it has an odor resembling that of piperidine and of bornylamine. It absorbs carbonic anhydride from the air, forming solid fenchylamine fenchyl carbamate. 2 Fenchylamine hydrochloride, C 10 H 17 NH 2 -HC1, dissolves in water and alcohol, and by slow crystallization is obtained in transparent prisms. It is readily soluble in ether. The platinochloride, (C 10 H 17 NH 2 ) 2 H 2 PtCl 6 , crystallizes from water in long, thin, hydrated prisms, which effloresce when kept over sulphuric acid. The hydriodide is also rather soluble in water and dilute alcohol, and separates in well defined crystals. The nitrate is distinguished by its great power of crystallization. Fenchylamine sulphate forms needles or plates, which are only moderately easily soluble. The picrate differs from bornylamine picrate in that it is readily soluble in ether. The tartrate may be precipitated from an aqueous solution by alcohol. The neutral oxalate is sparingly soluble. Fenchylamine nitrite, C 10 H 17 NH 2 HNO 2 , is moderately stable, readily soluble in water, and sparingly in a concentrated so- dium nitrite solution ; hence, small lustrous needles of fen- chylamine nitrite are precipitated on the addition of a sodium nitrite solution to a concentrated, neutral solution of a fenchyl- amine salt. Formyl fenchylamine, 3 C 10 H 17 NHCHO, is obtained by the action of ammonium formate on fenchone ; it is also formed by the treat- ment of fenchylamine with chloral. It crystallizes from dilute alcohol in lustrous leaflets, and melts, for the most part, at 87°, although some portions remain solid until the temperature rises to 112°. 'Wallach, Ann. Chem., 272, 105. 2 Wallach Griepenkerl and Liihrig, Ann. Chem., 269, 358. »Wallach, Ann. Chem., 263, 140. METHYL FENCHYLAMINE. 349 Acetyl fenchylamine, 1 C 10 H 17 NH-COCH 3 , is prepared by heating the free amine with acetic anhydride ; it crystallizes from ether, and melts at 98°. It is not very characteristic. Propionyl fenchylamine, 2 C 10 H 17 NHCOC 2 H 5 , melts at 123°. Butyryl fenchylamine, 2 C, 0 H 17 NH-COC 3 H 7 , melts at 77.5°. Benzoyl fenchylamine, 1 C 10 H 17 NH-COC 6 H S , is produced by the action of benzoyl chloride on an ethereal solution of the amine. After evaporation of the ether, the syrupy residue is washed with water which dissolves the fenchylamine hydrochloride formed in the reaction. The resultant solid product is then dissolved in alcohol, and the benzoyl compound is precipitated with dilute sodium hydroxide, free benzoic acid being thus removed. It melts at 133° to 135°. Difenchyloxamide, 1 (CONHC 10 H 17 ) 2 , results on mixing oxalic ester (one molecule) and fenchylamine (two molecules); it solidifies after standing for some time. It crystallizes from alcohol in long prisms or quadratic, thin plates, melting at 188°. Fenchylcarbamide, 1 C 10 H 17 NH-CONH 2 , is prepared by boiling the solution of equal molecular proportions of fenchylamine hydro- chloride and potassium isocyanate ; it separates from the cold solution in small needles, melting at 170° to 171°. Fenchyl phenylthiocarhamide, 1 C 10 H 17 NHCSNHC 6 H 5 , is formed when the dilute ethereal solutions of equal molecules of fenchyl- amine and phenylthiocarbimide are mixed ; the reaction is rather violent. This compound is especially well adapted for the characterization of fenchylamine ; it is sparingly soluble in cold alcohol and separates from this solvent in brittle, acute crystals, while it is deposited from dilute solutions in colorless, brilliant, well defined crystals, melting at 153° to 154°. Optically inactive fenchyl phenylthiocarbamide melts at 169° to 170°. 3 Difenchylthiocarbamide, 1 CS(NHC 10 H 17 ) 2 , is obtained when carbon bisulphide is added to an ethereal solution of fenchylamine, and the resultant dithiocarbamic acid salt is boiled with alcohol for a short time. It separates from the cold solution in the form of white leaflets, melting at 210°. Methyl fenchylamine, C 10 H 17 NHCH 3 . — When an ethereal solu- tion of fenchylamine is treated with methyl iodide, a mixture of mono- and di-methyl fenchylamine hydriodides is produced and gradually crystallizes from the ethereal solution. The two salts may be readily separated by crystallizing from water in which the 1 Wallach, Griepenkerl and Ltihrig, Ann. Chem., 269, 358. 2Wallach and Binz, Ann. Chem., 276, 317; compare Zeitschr. für physik. Chem., 12, 723. 3 Wallach, Ann. Chem., 272, 105. 350 THE TERPENES. salt of the mono-methyl base is more sparingly soluble than that of the di-methyl derivative. Mono-methyl fenchylamine, derived from its hydriodide, is an oil of specific gravity 0.8950 at 20° ; it boils at 201° to 202°, has a refractive index, n^ = 1.46988, at 20°, and is a weaker base than fenchylamine. Its hydrochloride forms prismatic crys- tals, and is stable when exposed to the air ; it is insoluble in ether, whilst fenchylamine hydrochloride is easily soluble (method of separation of fenchylamine and methyl fenchylamine). Nitroso-methyl fenchylamine, /CH S C 10 H n N/ Ntro is precipitated when a solution of methyl fenchylamine hydro- chloride is treated with a solution of sodium nitrite ; it first forms an oil which solidifies in the cold. It may be purified by dissolv- ing in alcohol and precipitating with ice, and melts at 52° to 53°. Benzyl fenchylamine, 1 C 10 H 17 NH-CH 2 C 6 H 5 , is prepared by boil- ing the molecular proportions of fenchylamine and benzyl chloride in a reflux apparatus for about one hour ; benzyl fenchylamine hydrochloride separates on cooling, is washed with ether to re- move fenchylamine hydrochloride, and saponified with alkali. It is a thick oil, boils at 190° to 191° at 16 mm. pressure, has a feeble basic odor, and a sp. gr. of 0.9735 at 20°. Its hydrochloride and platinochloride form well defined crystals. Nitroso-benzyl fenchylamine, /CH 2 C 6 H 5 C 10 H n N/ crystallizes from alcohol or ether in prisms, and melts at 93°. Benzylidene fenchylamine, 1 C 10 H 17 N = CHC 6 H 5 , is formed with development of heat and separation of water when the theoretical quantities of fenchylamine and benzaldehyde are allowed to react. On cooling, the reaction-product solidifies to a hard mass which crystallizes from methyl alcohol in splendid needles, melting at 42°. Inactive benzylidene fenchylamine is obtained as an oil by combining equal amounts of the levo- and dextro-rotatory modifications. 2 The hydrochloride of the benzylidene derivative is hygroscopic, and readily decomposes with formation of benzaldehyde. 1 Wallach, Griepenkerl and Lührig, Ann. Chem., 269, 358. »Wallach, Ann. Chem., 272, 105. FENCHOLENAMINE. 351 Ortho-oxybenzylidene fenchylamine, 1 C ]0 H 17 N = CHC 6 H 4 OH, re- sults by gently warming salicylic aldehyde with fenchylamine ; it crystallizes from alcohol in yellow needles, and melts at 95°. Acids readily resolve this compound into its components. The optically inactive derivative melts at 64° to 65°. Para-oxybenzylidene fenchylamine, 2 C 10 H 17 N = CHC 6 H 4 OH, is prepared in an analogous manner to the preceding compound by condensing p-oxybenzaldehyde with fenchylamine ; it melts at 175°. Ortho-methoxybenzylidene fenchylamine, 2 C 10 H 17 N = CHC 6 H 4 0- CH 3 , is produced by the condensation of fenchylamine and o-meth- oxybenzaldehyde ; it melts at 56°. Para-methoxybenzylidene fenchylamine melts at 54° to 55°. Fenchylamine forms a solid condensation-product, C 16 H 27 N0 2 , with aceto-acetic ester; it has not been further investigated. The following table contains the mean values obtained for the specific and molecular rotatory powers of fenchylamine, prepared from dextro-fenchone, and of its derivatives in chloroform solu- tions (Wallach and Binz 2 ). Fenchonoxime Fenchylamine Formyl fenchylamine Acetyl fenchylamine Propionyl fenchylamine Butyryl fenchylamine Benzylidene fenchylamine o-Oxybenzylidene fenchylamine p-Oxybenzylidene fenchylamine o-methoxybenzylidene fenchylamine, ^-methoxybenzylidene fenchylamine Melting Point. [*h 165° +52.44° + 87.40° —24.89° — 38.00° (114°) 99° —36.56° — 66.04° —46.62° — 90.73° 123° —53.16° —110.88° 77.5° —53.11° —118.19° 42° +73.14° + 175.90° 94° +66.59° +170.77° 175° +72.00° + 184.65° 56° +59.20° + 160.09° 55° +78.05° +211.07° 6. FENCHOLENAMINE, C 9 H 15 CH 2 NH 2 . A base of the composition, C 10 H 1? NH 2 , which bears the same relation to camphylamine as fenchylamine to bornylamine, was obtained by Wallach 3 by the reduction of fenchonoxime anhydride (a-fencholenonitrile), C 9 H 15 CN. This amine was carefully studied by Wallach and Jenkel, 4 and designated as fencholenamine. It is prepared by adding fifteen grams of sodium to a solution of twenty-five grams of «-fencholenonitrile in one hundred and 'Wallach, Griepenkerl and Lührig, Ann. Chem., 269, 358. 2 Wallach and Binz, Ann. Chem., 276, 317; compare Zeitschr. für physik. Chem., 12, 723. »Wallach, Ann. Chem., 263, 138. *Wallach and Jenkel, Ann. Chem., 269, 369. 352 THE TERPENES. twenty-five grams of absolute alcohol. Toward the end of the reaction a small quantity of water is added, the liquid is heated until all sodium is dissolved, and the product is then poured into water. After acidulating with sulphuric acid, the undecomposed nitrile is distilled off in a current of steam, the free base is liber- ated from the residue by means of sodium hydroxide, is separated and fractionated in vacuum. The fencholenamine distills over at 110° to 115° under 21 mm. to 24 mm., while on continued dis- tillation a small fraction is obtained at 115° to 147°, and then, at 147° to 148°, a base, C 10 H 2l NO, is obtained (see below). Fencholenamine boils at 205° under atmospheric pressure ; it readily absorbs carbonicanhydride,and is an unsaturated compound. Fencholenamine nitrate, C 10 H 17 NH 2 «HNO 3 , is formed by dis- solving five grams of the base in eleven grams of nitric acid of sp. gr. 1.105. It may be obtained in splendid crystals by re- crystallization from twice its weight of water. Fencholenamine sulphate, (C 10 H 19 N) 2 'H 2 SO 4 , crystallizes in plates, and is sparingly soluble in water, readily in dilute sulphuric acid. Its aqueous solution is not decomposed by boiling. Like an unsaturated amine, fencholenamine combines with two molecules of hydrochloric acid. When hydrogen chloride is passed into a methyl alcoholic solution of the base and the alcohol is then allowed to evaporate, hydrochlorofencholenamine hydro- chloride, C, 0 H lg ClNH 2 -HCl, is obtained in well defined crystals. This salt yields a fencholenamine containing only a small amount of chlorine when it is treated with a solution of sodium hydroxide in the cold. Fencholenamine oxalate is sparingly soluble in water. Acetyl fencholenamine, C 10 H 17 NHCOCH 3 , is prepared by the addition of acetic anhydride to an ethereal solution of the base. It is a thick oil, and boils at 180° under a pressure of 21 mm. Benzoyl fencholenamine, C ln H )7 NHCOC 6 H 5 , is easily obtained by the Schotten-Baumann method ; it melts at 88° to 89°. The condensation-products of fencholenamine with aldehydes are oils ; the compound obtained from furfural boils at 167° under a pressure of 16 mm. When fencholenamine is treated with nitrous acid, it is con- verted into fencholenyl alcohol. The above-mentioned base, C 10 H 21 NO, formed together with fencholenamine by the reduction of a-fencholenonitrile, may be easily separated from fencholenamine by means of its very soluble oxalate. It boils at 147° to 148° under 21 mm. to 24 mm. By boiling with dilute sulphuric acid, this amine loses water and appears to be converted into fencholenamine. CAMPHOL YL PHENYLTHIOCAKBAMEDE. 353 7. CAMPHOL AMINE , C 9 H 17 CH 2 NH 2 . Campholamine is prepared by reducing campholonitrile, 1 C 9 H 17 CN, with sodium in alcoholic solution. (Campholic acid, C 9 H 17 COOH, is obtained by heating a solution of camphor in benzene with sodium.) This base is a colorless oil, lighter than water, and is only slightly soluble in water. It boils at 210°, and quickly absorbs carbonic anhydride from the air forming a crystalline salt (Errera 2 ). Campholamine hydrochloride, C 10 H 21 N-HC1, is insoluble in ether, and crystallizes from water in silvery laminae. The platino- chloride separates from alcohol in yellow plates. Campholamine nitrate, C^H^N'HNOg, is sparingly soluble in water, and may be recrystallized from boiling water. When heated rapidly, the salt melts and decomposes at 220°. Benzoyl campholamine, C 10 H 19 NH-COC 6 H 5 , is prepared by the action of benzoyl chloride on an ethereal solution of the base ; it is insoluble in water, readily soluble in the other ordinary sol- vents, and melts at 98°. Campholyl phenylthiocarbamide, C 10 H 19 NHCS-NHC 6 H 5 , is pro- duced by the action of phenylthiocarbimide on an ethereal solution of the base, the reaction being energetic. When recrystallized from dilute alcohol, it separates in colorless needles, melting at 117° to 118° ; it is sparingly soluble in petroleum ether. When a solution of campholamine hydrochloride is warmed with silver nitrite, campholyl alcohol, C 10 H 19 OH, and a hydro- carbon, C 10 H 18 , are formed. Errera 2 terms this hydrocarbon, oampholene. i Errera, Gazz. Chim., 22, I., 205; Ber., 25, 466, Ref. ^Errera, Gazz. Chim., 22, II., 109; Ber., 26, 21, Ref. 28 II. BASES WHICH MAY BE REGARDED AS DERIVA- TIVES OF THE HYDROCYMENES. A. AMINES, C 10 H 15 NH 2 , CONTAINING TWO ETHYLENE LINKAGES. 1. CARVYLAMINES, C 10 H 15 NH 2 . By the reduction of carvoxime, C 10 H 14 NOH, with sodium amalgam and acetic acid, Goldschmidt 1 obtained a base which he called carvylamine, C 10 H 15 NH 2 . The existence of this compound was subsequently questioned by Wallach, 2 since he obtained dihy- drocarvylamine, C 10 H 17 NH 2 , by reducing carvoxime with sodium and alcohol ; Wallach also found dihydrocarvylamine, C 10 H 17 NH 2 , to be identical with the base, prepared by Leuckart and Bach 3 and by Lampe 4 on the treatment of carvone with ammonium formate, which had previously been called " carvylamine," C 10 H 15 NH 2 . Although in the German edition of this book, Dr. Heusler con- siders Goldschmidt's and Leuckart's carvylamine as identical with Wallach' s dihydrocarvylamine, it appears to the translator that Goldschmidt 5 has sufficiently proved the existence of his carvyl- amine, C 10 H 15 NH 2 , and has shown it to be quite different from dihydrocarvylamine. According to Goldschmidt, 5 when an alcoholic solution of dextro- carvoxime is reduced with sodium amalgam, or zinc dust, and acetic acid, two optically active, isomeric bases are formed, which are designated as a-d- and /9-d-carvylamine, C 10 H 15 NH 2 . Levo-car- voxime likewise gives rise to two bases a-l- and /9-1-carvylamine, whose derivatives have the same melting point, solubility, etc., as those of the corresponding bases obtained from d-carvoxime, while their optical rotation is the opposite. Two racemic compounds, corresponding to the a- and /3-carvylamines, have been separated in the form of their benzoyl derivatives, so that altogether six isomeric benzoyl carvylamines have been isolated. iH. Goldschmidt, Ber., 19, 3232; 20, 486; 26, 2084. 2 Wallach, Ann. Chem., 275, 120. a Leuckart and Bach, Ber., 20, 105. «Lampe, Inaug. Diss., Göttingen, 1889. s Goldschmidt and Fischer, Ber., 30, 2069. 354 ß-D-CARVYL PHENYLCAEB AMIDE. 355 The reduction of carvoxime is accomplished as follows. An alcoholic solution of d-carvoxime is heated with zinc dust and acetic acid on the water-bath until no further precipitation of the oxime takes place on pouring a little of the reaction-mixture into water. The excess of zinc is filtered off, the filtrate is diluted with water, rendered acid with hydrochloric acid, and consider- able regenerated carvone is extracted with ether. The acid liquid is then rendered alkaline with sodium hydroxide, and again extracted with ether ; after drying over potash and distilling off the ether, the basic residue is rectified in vacuum, the product boiling at 94° under 10 mm. pressure. The liquid distillate has a basic odor, is sparingly soluble in water, and consists of two bases, whose separation is accom- plished by means of their nitrates ; the nitrate of /9-d-carvylamine is more difficultly soluble in water than its isomeride. The basic mixture is neutralized with dilute nitric acid, and the resultant salts are crystallized from a small quantity of warm water ; the /9-salt separates at first, and the filtrate may be used for the preparation of the a-derivatives. The free bases may be obtained from their hydrochlorides or nitrates by the action of alkalis ; they have a decided basic odor, and rapidly absorb carbon dioxide from the air, forming solid carbonates. a-d-Carvylamine hydrochloride, C 10 H 15 NH 2 -HC1, crytallizes from absolute alcohol in fine needles, melts with decomposition at 180°, and is readily soluble in water. a-d-Carvyl phenylcarbamide, C 10 H 15 NH*.CONHC 6 H 5 , can not be obtained entirely free of the /9-derivative ; it is crystalline, and melts at 187° to 191°. Benzoyl-a-d-carvylamine, C 10 H 15 NH-COC 6 H 5 , is produced by treating an aqueous solution of the a-d-nitrate with alkali and benzoyl chloride ; it usually contains some of the /5-derivative as an impurity, but after repeated crystallization from methyl alco- hol, it is freed from most of the /3-compound. It crystallizes from methyl alcohol in long, white needles, and melts at 169° ; it is levorotatory, [a]x> = — 91.9°. a-d-Carvyl carbamide, C 10 H 15 NH-CONH 2 , is formed by warming a solution of the hydrochloride with potassium cyanate ; it crystal- lizes from hotwater in white, miscroscopic needles,and melts atl87°. The /3-d-carvylamine may be readily obtained in a pure condi- tion, since its nitrate is much more sparingly soluble in water than the a-compound. /?-d-Carvyl phenylcarbamide, C 10 H 15 NHCONHC 6 H 5 , crystallizes in small, white needles, and melts at 138°. 356 THE TERPENES. Benzoyl-/9-d-carvylamine, C 10 H 15 NH-COC 6 H 5 , is prepared from the /?-d-nitrate by treating with alkali and benzoyl chloride ; it crystallizes from methyl alcohol in colorless needles, melts at 103°, and is more readily soluble in all solvents than the «-Com- pound. It is dextrorotatory, [a]^ = -f 176.6°. When 1 -carvoxime is reduced in alcoholic solution with zinc dust and acetic acid in a manner similar to that described above, a mixture of two isomeric bases is obtained, which boils at 94° to 95° under 10 mm. pressure. These bases are also separated by means of their nitrates, and the benzoyl derivatives are formed like the corresponding d-compounds. Benzoyl-a-l-carvylamine, C 10 H 15 NH-COC 6 H 5 , crystallizes from methyl alcohol in long, white needles, melts at 169°, and is dex- trorotatory, [a\ D = + 92.6°. Benzoyl-ß-1-carvylamine, C 10 H 15 NH COC 6 H 5 , crystallizes from methyl alcohol, melts at 103°, and is levorotatory, [a] z> = - 175.4°. Racemic benzoyl-a-carvylamine, (C 10 H 15 NH-COC 6 H 5 ) 2 , is ob- tained by crystallizing together equal weights of the a-d- and a-1- derivatives from methyl alcohol ; it forms fine, white needles, and melts at 141°. Racemic benzoyl-/2-carvylamine, (C 10 H 15 NH-COC 6 H 5 ) 2 , is pro- duced from the two /9-compounds ; it crystallizes from methyl alcohol in small prisms, and melts at 140°. It is more readily soluble in all solvents than the preceding compound. When the two isomeric racemic derivatives are rubbed together, a mixture results, which melts at about 132°. B. AMINES, C 10 H 17 NH 2 , CONTAINING ONE ETHYLENE LINKAGE. 1. DIHYDROCARVYLAMINE, C 10 H 17 NH 2 . By the treatment of carvone with ammonium formate, Leuckart and Bach, 1 and Lampe 2 obtained a base which they called " carvyl- amine," C 10 H 15 NH 2 . Wallach 3 subsequently showed that this compound could be more conveniently prepared by reducing carvoxime with sodium and alcohol, and further that its compo- sition was not expressed by the formula, C 10 H 15 NH 2 , but that it had the constitution, C 10 H 17 NH 2 , dihydrocarvylamine. Wallach has 1 Leuckart and Bach, Ber., 20, 105. 2 Lampe, Inaug. Diss., Göttingen, 1889. 3 Wallach, Ann. Chem., 275, 120; Ber., 24, 3984. DIHYDROCARVYLAMINE HYDROCHLORIDE. 357 also regarded dihydrocarvylamine as chemically identical with Goldschmidt's carvylamine, C 10 H 15 NH 2 , but more recent publi- cations 1 by Goldschmidt indicate that this view can no longer be maintained. For the preparation of dihydrocarvylamine according to Leuckart's method, ten grams of carvone are heated with eleven grams of ammonium formate in sealed tubes at 180° to 200°, for five or six hours. On cooling, the tubes contain the formyl derivative of the base as a dark, viscous mass, together with some unchanged ammonium formate. The formyl com- pound is treated with water and extracted with ether ; the ethereal solution is separated, the ether distilled off, and the resultant product saponified with alcoholic potash. After the alcohol is re- moved by distillation, the base is distilled with steam, and recti- fied in vacuum. The yield is seventy to eighty per cent, of the theoretical (Wallach 2 ). In order to prepare the base by the reduction of carvoxime, 2 twenty grams of the oxime are dissolved in one hundred and seventy-five cc. of absolute alcohol and treated gradually with twenty-five grams of sodium, the operation requiring one-half hour ; the last particles of sodium are dissolved by the addition of more alcohol. The product is distilled with steam, and the base purified by distillation in vacuum. Dihydrocarvylamine boils without appreciable decomposition at 218° to 220°; under 15 mm. pressure it boils at 93° to 95°. It has a specific gravity of 0.889 and refractive power, n^ = 1 .48294, at 20°. It is optically active ; on mixing the solutions of equal quantities of the dextro- and levo-modifications, a racemic com- pound is obtained, whose derivatives differ materially from those of the active bases in melting point and solubility. It readily absorbs carbonic anhydride from the air. Dihydrocarvylamine hydrochloride, C 1() H 17 NH 2 HCl, is precipi- tated by passing hydrochloric acid gas into a dry ethereal solution of the base ; by the long-continued action of hydrogen chloride, this salt is dissolved owing to the formation of a dihydrochloride, which is soluble in ether. The monohydrochloride melts at about 200°, and decomposes readily into ammonium chloride and terpi- nene; at a higher temperature this terpene is partially converted into cymene by the elimination of hydrogen : — C 10 H 17 NH 2 HCl = NH 4 C1 +C 10 H l6 ; Ch>H 16 = H, -f- Ci 0 H u . i Goldschmidt and Fischer, Ber., 80, 2069. 2 Wallach, Ann. Chem., 275, 120; Ber., 24, 3984. 358 THE TEKPENES. Dihydrocarvylamine sulphate crystallizes in characteristic, lus- trous leaflets, and is sparingly soluble. The oxalate is also diffi- cultly soluble. When a solution of dihydrocarvylamine hydrochloride is warmed with a solution of sodium nitrite, dihydrocarveol is formed, together with dipentene (inactive limonene) ; the forma- tion of this hydrocarbon is of interest since it indicates a trans- formation of carvone into limonene. Acetyl dihydrocarvylamine, C 10 H 17 NHCOCH 3 , is obtained by warming the free base with acetic anhydride; it separates at first as an oil which solidifies after some time, and may be crystallized from hot water. It melts at 132°. Benzoyl dihydrocarvylamine, C 10 H 17 NH-COC 6 H 5 , crystallizes from methyl alcohol in needles, and melts at 181° to 182°. Dihydrocarvyl phenylcarbamide, C 10 H 17 NH CO NHC fi rT , melts at 191°. 7 6 5 Dihydrocarvyl phenylthiocarbamide, C 10 H 17 NH-CS-NHC 6 H 5 , is prepared by mixing the methyl alcoholic solutions of the molec- ular proportions of the base and phenylcarbimide ; it forms small, transparent prisms, which melt at 125° to 126°. When equal quantities of the dextro- and levo-modifications are crystallized together from methyl alcohol, the inactive thiocarbamide is ob- tained ; it is more readily soluble, and does not form as well de- fined crystals as the active modifications, and melts at 119°. ^ Dihydrocarvyldiamine, 1 C 10 H 16 (NH 2 ) 2 , is produced on the reduc- tion of hydroxylaminocarvoxime with alcohol and sodium. It is a colorless liquid, having a basic odor, boils at 258° to 260° under atmospheric pressure, and at 122° to 123° (10 mm.); it absorbs carbon dioxide from the atmosphere. Its hydrochloride is hygroscopic, and the aurichloride crystallizes in long needles. The oxalate melts at 135° to 140°, the dibenzoyl derivative at 275° to 276°, the diphenylcarbamide at 214° to 216°, and the diphenylthiocarbamide at 179° to 180°. On the dry distillation of dihydrocarvyldiamine, a hydro- carbon, C 10 H 14 , isomeric with cymene, is formed ; it is an unsatu- rated compound, and boils at 170° to 175°. 2. CARYLAMINE, C 10 H 17 NH 2 . Carylamine is formed when one part of the oily caronoxime, Ci 0 H 16 NOH, is dissolved in twenty-oue parts of alcohol and re- duced with three parts of sodium (Baeyer 2 ). 1 Harries and Mayrhofer, Ber., 82, 1345. «Bayer, Ber., 27, 3486. DTHYDROEUCARVYLAMINE. 359 It has no characteristic odor. Its alcoholic solution is stable towards potassium permanganate, hence Baeyer assumes that the hexamethylene ring in carylamine contains either a para-linking or a trimethylene ring. . Carylamine hydrochloride, C 10 H 17 NH 2 HC1, is obtained by sat- urating an ethereal solution of the base with hydrochloric acid gas. On evaporation of the ether, the salt remains as a crystal- line mass, which is readily soluble in water, alcohol and ether. When its aqueous solution is evaporated, it is converted into the isomeric vestrylamine hydrochloride. The aqueous solution of carylamine hydrochloride gives no precipitate with platinic chloride. , , , 0 . Benzoyl carylamine, C 10 H 17 NH-COC fi H 5 , is prepared by Schot- ten-Baumann's method, and crystallizes from ethyl acetate in large, flat prisms, which melt at 123°. Caryl phenyltMocarbamide, C 10 H 17 NH-CS-NHC 6 H 5 , melts at 145° to 146°. 3. VESTRYLAMINE, C 10 H 17 NH 2 . Carylamine is readily transformed into the isomeric, unsaturated vestrylamine 1 by saturating an alcoholic solution of carylamine with hydrogen chloride, and heating the reaction-product on the water-bath for one and one-half days; the hydrochloride of vestrylamine is so obtained as a syrup, which gradually solidifies to a crystalline mass. . , . . Vestrylamine resembles carylamine in odor, but is immediately attacked by permanganate. When treated with benzoyl chloride and sodium hydroxide, it yields a resinous product from which crystals of benzoyl carylamine may be separated, hence the con- version of carylamine into vestrylamine is not quantitative.^ When vestrylamine hydrochloride is subjected to dry distilla- tion, it is decomposed into carvestrene and ammonium chloride : C 10 H 17 NH 2 HC1 = C 10 H 16 + NH 4 C1. Carylamine hydrochloride likewise forms carvestrene by distil- lation, but in this case the change is probably preceded by an intramolecular transformation of carylamine hydrochloride into vestrylamine hydrochloride. 4. DIHYDROEUC AR VYL AMINE , C 10 H 17 NH 2 . Dihydroeucarvylamine was obtained by Baeyer 2 in the reduc- tion of eucarvoxime and of dihydroeucarvoxime hydriodide with "Bayer, Ber., 21, 3486. sBayer, Ber., 21, 3487; Baeyer and Villiger, Ber., 31, 2067. 360 THE TERPENES. sodium and alcohol. It has no characteristic odor, and its alco- holic solution immediately reduces potassium permanganate. It boils at 116° to 117° under a pressure of 40 mm. 1 Dihydroeucarvylamine hydrochloride is crystalline and rather sparingly soluble. The platinochloride is also crystalline and difficultly soluble. Benzoyl dihydroeucarvylamine, C 10 H 17 NH-COC 6 H 6 , obtained by Schotten-Baumann's method, is sparingly soluble in ether, and crystallizes from ethyl acetate in long needles, melting at 155° to 156°. It is unstable towards permanganate. Dihydroeucarvyl phenylcarbamide, 1 C 10 H 17 NH • CONHC H melts at 142°, and the phenylthiocarbamide, C 10 H 17 NHCSNH- C 6 H 5> crystallizes from methyl alcohol in transparent plates, and melts at 120° to 121°. 5. THUJYL AMINE (TANACETYLAMINE), C 10 H 17 NH 2 . Tanacetylamine, C 10 H 17 NH 2 , is formed when ten parts of tanacetoxime (m. p. 51.5°) are reduced with twenty-five parts of sodium and fifty parts of alcohol (Semmler 2 ). The same base, designated by Wallach as thujylamine, is obtained by reducing thujonoxime (m. p. 54°) with alcohol and sodium (Wallach 3 ). According to Semmler, this compound boils at 80.5° under a pressure of 14 mm., has the specific gravity 0.8743 and a re- fractive power, n^ = 1.462, at 0°. According to Wallach, it boils at 195°, has a specific gravity of 0.8735 and refractive index, n B = 1.4608, at 20°. Thujylamine absorbs carbonic anhydride with great readiness forming the carbamate, which melts at 106° to 107°. The nitrate is rather difficultly soluble in water, and melts at 167° to 168°. The hydrochloride is precipitated from the ethereal solution of the base as a gelatinous mass, which melts at 260° to 261°. When dry distilled, it yields ammonium chloride and a terpene, QoH-w which Wallach calls thujene and Semmler designates as tanacetene. This hydrocarbon boils at 60° to 63° under a pres- sure of 14 mm., has the specific gravity 0.8508 and refractive power, np = 1.476, at 20° (Semmler). According to TschugaefF, 4 the dry distillation of thujylamine hydrochloride gives isothujene and not thujene. It contains two ethylene linkages. Wallach, Ann. Chem., 305, 223. 2 Semmler, Ber., 25, 3345. »Wallach, Ann. Chem., 286, 96. 'Tsehugaeff, Ber., 34, 2270. ISOMERIC THUJYLAMINE. 361 Thujyl phenylcarbamide, C 10 H 1? NH CO NHC 6 H 5 , results by the interaction of thujylaniine and phenylcarbimide ; it crystal- lizes in prisms, and melts at 120° (Wallach). Dimethylthujylamine, 1 C 10 H 17 N(CH 3 ) 2 , is formed as a by-product during the preparation of thujyl trimethyl ammonium iodide ; it boils at 213.5° to 214°, has a sp. gr. 0.8606 at 20°/4°, and \_fi\j) = -f 141 .76°. Its hydrochloride is very easily soluble in water and alcohol, the platinochloride separates from hot alcohol as an orange red, crystalline powder, and the nitrate crystallizes readily and is only sparingly soluble in water and alcohol. Thujyl trimethyl ammonium iodide, 1 C 10 H 17 N(CH 3 ) 3 I, is formed by the action of methyl iodide and potassium hydroxide on thujyl- amine ; it crystallizes from a mixture of chloroform and methyl alcohol in long, prismatic crystals, has the specific rotatory power in chloroform solution, [0:]^= -f 42.61°, and is only sparingly soluble in cold water. Thujyl trimethyl ammonium hydroxide, 1 C 10 H 17 N(CH 3 ) 3 OH, is obtained as a crystalline mass by treating the preceding com- pound with moist silver oxide ; on dry distillation it is decomposed with the formation of thujene, C 10 H 16 (b. p. 151° to 153°, sp. gr. 0.8263 at 20°/4°, n B = 1.45022 at 20°, and \a\ D = - 8.23°). It has already been mentioned that three isomeric thujonoximes are known (see page 228). These oximes yield three different amines on reduction. Thujonoxime, melting at 54°, gives the above described thujylamine ; the isomeric thujonoxime, melting at 90°, forms the isomeric thujylamine, boiling at 193°; and isothujonoxime, melting at 119°, yields isothujylamine, boiling at 200° to 201°. ISOMERIC THUJYLAMINE, C 10 H 17 NH 2 , PREPARED FROM THE ISOMERIC THUJONOXIME, MELTING AT 90°. When the isomeric thujonoxime, melting at 90°, is reduced with sodium and alcohol, it yields a base, C 10 H 17 NH 2 , which boils at 193°, and at 20° has the specific gravity 0.875 and refractive index, n^ = 1.46256 (Wallach 2 ). It absorbs carbonic anhydride slowly. Its nitrate crystallizes in needles, is readily soluble, and melts at 124°; the hydrochloride separates in tablets, and melts at 216°; the phenylcarbamide forms transparent tablets, which melt at 110°. iTscliugaeff, Ber., 3 k, 2276. «Wallach, Ann. Chem., 286, 96. 362 THE TEKPENES. Wallach 1 had previously obtained a thujylamine, boiling at 198° to 199°, by heating crude thujone with ammonium formate. When the hydrochloride of this base is submitted to dry distilla- tion, it is decomposed into ammonium chloride and thujene, C 10 H 16 ; this hydrocarbon boils at 172° to 175°, has the specific gravity 0.840 and refractive index, n^ = 1.4761, at 20°. Whether this amine is identical with the thujylamine prepared from thujonoxime (m. p. 54°), or is to be regarded as a derivative of carvotanacetone — the latter view is suggested by the high tem- perature at which the compound is formed — can only be deter- mined by a renewed investigation. 6. ISOTHU J YL AMINE , C 10 H 17 NH 2 . Isothujylamine is produced when isothujonoxime (m. p. 119° to 120°) is reduced with sodium and alcohol (Wallach 2 ). It boils at 200° to 201°, has a specific gravity of 0.865 and a refractive index, n^ == 1.468, at 20°; it absorbs carbonic anhy- dride very feebly. The nitrate is sparingly soluble, and melts at 163°. The hydrochloride is precipitated from a solution of the base in dry ether by hydrochloric acid gas ; it may be crystallized from a mixture of chloroform and petroleum ether, and melts at 180° to 181°. When this salt is submitted to dry distillation, it is de- composed into ammonium chloride and a terpene, which seems to be identical with the above-mentioned thujene ; the terpene boils at 170° to 172°, its sp. gr. is 0.836 and refractive power, n^ = 1.47145, at 22°. Isothujylcarbamide, C 10 H 17 NHC(>NH 2 , is prepared by the in- teraction of isothujylamine hydrochloride and potassium isocya- nate j it melts at 158° to 159°. Isothujyl phenylcarbamide, C 10 H 17 NH-CO-NHC 6 H 5 , forms small needles, which are readily soluble in alcohol, and melt at 178°. Isothujyl phenylthiocarbamide, C 10 H 17 NH-CS-NHC 6 H 5 , crystal- lizes in needles, dissolves sparingly in methyl alcohol, and melts at 152° to 153°. 7. PULEGYLAMINE, C 10 H 17 NH 2 . Pulegylamine is obtained by reducing the normal pulegonoxime, C ]0 H 16 NOH, in an alcoholic solution with sodium. It is a crys- talline compound, and is purified by means of its readily soluble oxalate; it melts at about 50°, boils at 205° to 210°, and com- bines with great readiness with carbonic anhydride. iWallach, Ann. Chem., 272, 109. sWallach, Ann. Chem., 286, 97. METHYL PULEGONAMINE. 363 Pulegylamine hydrochloride is insoluble in ether, and yields a carbamide, melting at 104° to 105°, when treated with potassium isocyanate. Pulegyl phenylcarbamide, obtained from the free amine and car- banile, melts at 154° to 155° (Wallach 1 ). Beckmann and Pleissner 2 obtained a base, C 10 H 19 ON, which they termed pulegonamine, by the action of hydriodic acid on the "hydrated pulegonoxime," C 10 H 19 NO 2 . According to these chemists, this amine is prepared when ten parts of "hydrated pulegonoxime " are treated with twenty parts of strong hydriodic acid and a little red phosphorus ; the mixture is warmed until the reaction commences, and is then allowed to stand for some time. Two layers are formed, a light colored aqueous solution and a dark oil. The product is diluted with water, and decolor- ized with thiosulphate, the oil being dissolved. The sulphur and phosphorus are filtered ofP, the solution is shaken with ether, and then rendered alkaline ; the resulting pulegonamine is extracted with ether. On evaporation of the ether, the base remains as a yellowish oil, having a basic odor and bitter taste ; it decomposes when distilled. This amine does not reduce Fehling's solution, and does not give the isonitrile reaction. If hydrochloric acid gas be passed through its ethereal solution an oil is precipitated, which solidifies after repeated washing with ether, and crystallizes from absolute alcohol in long needles, melting at 117°. This salt is not homogeneous, but contains more chlorine than the formula, C 10 H 19 NOHC1, demands. Pulegonamine phenylthiocarbamide, CS X NHC,H 5 is obtained by the action of phenylthiocarbimide on a solution of pulegonamine in benzene ; it crystallizes from benzene in white plates, and melts at 198°. Benzoyl pulegonamine, C 10 H 18 ON-COC 6 H 5 , is formed by treating an ethereal solution of the base with benzoyl chloride ; it sepa- rates from dilute alcohol in lustrous, feathery crystals, which melt at 100.5° to 101°. Methyl pulegonamine, C 10 H 18 ONCH 3 , is produced by boiling pulegonamine with methyl iodide and decomposing the reaction- product with potash ; it is a light yellow oil, having a penetrating, •Wallach, Ann. Chem., 289, 347. 2 Beckmann and Pleissner, Ann. Chem., 262, 13. 364 THE TERPENES. fish-like smell. Its platinochloride, (C n H 22 NOCl) 2 PtCl 4 , crystal- lizes in well defined needles. When pulegonamine is boiled with potash, it is converted into pulegone and ammonia ; under the same conditions, methyl pule- gonamine yields pulegone and methylamine ; in both cases, how- ever, the resultant pulegone apparently contains a nitrogenous substance as an impurity. The constitution of pulegonamine, therefore, differs entirely from that of the other terpene bases. Beckmann and Pleissner assume that the isonitroso-group (NOH) in pulegonoxime is changed into the NH-group by treatment with hydriodic acid. C. AMINES, C 10 H 19 NH 2 , WITHOUT AN ETHYLENE LINKAGE. 1. C AR VOMENTHYL AMINE (TETBAHYDROCARVYLAMINE), C 19 H 19 NH 2 . (Amido-%-hexahydrocymme.') When the oxime of tetrahydrocarvone (carvomenthone), C 10 H I8 NOH, melting at 105°, is reduced with sodium and alcohol by the same method which serves for the preparation of menthyl- amine from menthonoxime (see page 368), an amine isomeric with menthylamine is obtained. Wallach 1 regards this compound as having the constitution of an amido-2-hexahydrocymene ; it may be designated as carvomenthylamine or tetrahydrocarvylamine : The optically active modifications of this base are obtained, together with optically active tetrahydrocarveol and tetrahydro- carvone, when phellandrene nitrosite is reduced with sodium and alcohol (Wallach and Herbig 2 ). JWallach, Ann. Chem., 277, 137. 2Wallach and Herbig, Ann. Chem., 287, 371. MENTHYLAMINE. 365 Carvomenthylamine is a liquid, and boils at 211° to 212°, -considerably higher than menthylamine ; the other properties of both amines are very similar. It unites with carbon dioxide with great readiness, forming a solid salt. Carvomenthylamine hydrochloride, C 10 H 19 NH 2 HC1, is insoluble in ether and sparingly soluble in cold water ; its optically active modifications melt at 199° to 204°, while the inactive derivative melts at 221° to 222°. It resembles menthylamine hydro- chloride in that it may be distilled at a high temperature with only slight decomposition. The platinochloride is very easily soluble in alcohol, more sparingly in water. Formyl carvomenthylamine, C 10 H lg NHCOH, is obtained as an oil by the distillation of the formate. It solidifies gradually, but on recrystallization it separates at first from all solvents as an oil. The inactive modification melts at 61° to 62°. Acetyl carvomenthylamine, C 10 H 19 NHCOCH 3 , is formed by warming the base with acetic anhydride ; it crystallizes from dilute alcohol in small needles. The active derivatives melt at 158° to 159°, whilst the inactive modification melts at 124° to 125°. Carvomenthyl phenylthiocarhamide, C 10 H 19 NH-CS*NHC 6 H 5 , is prepared by the action of phenylthiocarbimide on carvomenthyl- amine ; it forms a viscous mass, which solidifies slowly. The pure, inactive derivative crystallizes from methyl alcohol in small, white needles, which melt at 117°. Carvomenthyl carbamide, C 10 H 19 NH-CO-NH 2 , is best adapted for the characterization of carvomenthylamine. It is precipitated by heating carvomenthylamine hydrochloride r with a solution of potassium isocyanate ; it is insoluble in water, and is not readily soluble in hot alcohol. The racemic compound crystallizes from methyl alcohol in brilliant leaflets or needles, and melts at 193° to 194° ; the active modifications melt at 201° to 203°. Carvomenthyl phenylcarb amide, 1 C )0 H 19 NHCONHC 6 H 5 .— The inactive modification melts at 145° to 150°, and the active de- rivatives at 185° to 186°. Optically active carvomenthol 1 is formed when the salts of op- tically active carvomenthylamine are treated with a solution of sodium nitrite. 2. MENTHYLAMINE, C 10 H 19 NH 2 . Menthylamine was first prepared by Moriya 2 by the reduction of a nitro-compound, obtained by the action of strong nitric acid 1 Wallach and Herbig, Ann. Chem., 287, 371. 2 Moriya, Journ. Chem. Soc, 1881, 77. 366 THE TERPENES. on menthol, with tin and sulphuric acid ; the properties of this amine were very incompletely described. Andres and Andreef 1 subsequently showed that a base having a strong levorotatory power was formed by reducing levo-menthonoxime with sodium and alcohol. Wallach and Küthe 2 then obtained the same re- sults, although Wallach 3 had previously shown that a base, C 10 H 19 NH 2 , could be produced by the treatment of menthone with ammonium formate. According to Wallach and Küthe, levo-menthylamine prepared from levo-menthonoxime is strongly levorotatory, and is chemically different from the feebly dextrorotatory menthylamine, which may be obtained, together with some of the levorotatory isomeride, by the action of ammonium formate on levo-menthone. Wallach explains the simultaneous formation of both bases by the follow- ing considerations. Levorotatory menthone contains two asymmetric carbon atoms. When menthone is converted into menthylamine, the carbonyl group is changed into the group, CH-NH 2 , and a third asym- metric carbon atom is introduced, as shown by the formulas in which the asymmetric atoms are represented by heavy type : H, H 2 (j! CH 2 h,c bo 0 3 H 7 C 3 H, Menthone. Menthylamine. If it be assumed that the two asymmetric carbon atoms in levo-menthone and levo-menthonoxime influence the levorotatory power of these compounds in the same direction although to an unequal extent, the two substances can be represented : (-, -)C 10 H 18 O and (-, -)C 10 H 18 :NOH. By the transformation into menthylamine, the third asymmetric carbon atom may increase this levorotation and a levorotatory menthylamine may be formed which would be expressed by the symbol : (— — — ) C io H i9 N H 2 ; or, the third asymmetric atom may act in the opposite direction ] Andres and Andreef, Ber., 25, 618; 24, 560, Ref. 2 Wallach and Küthe, Ann. Chem., 276, 296; compare Ber., 25, 3313. "Wallach, Ber., 24, 3992. MENTHYLAMINE. 367 to those already present, and a compound be obtained which has a weaker power of rotation, or, as in the case under consideration, it may rotate the plane of polarized light slightly to the right ; the symbol of the resultant dextrorotatory menthylamine would be : (- + )C 10 H 19 NH 2 . This hypothesis, proposed by Wallach, explains the facts that levo- and dextro-menthylamines are not related to each other in the same manner that an object is to its reflection, and, moreover, that they are chemically different. It would be expected that compounds having rotatory powers exactly opposite to those of the above-mentioned menthylamines would result if dextro-menthone were employed instead of levo- menthone. Experiments in this direction were made by Wallach and Küthe, and by Negoworoff, 1 but the preparation of such bases in a condition of purity has not succeeded. The behavior of the two menthylamines towards nitrous acid is quite characteristic. Under the influence of this reagent, 1-men- thylamine is readily converted into the ordinary, solid 1-menthol, while under the same conditions, d-menthylamine yields large quantities of menthene. Consequently d-menthol, corresponding^ to d-menthylamine, possesses a much greater tendency to lose the elements of water than the common 1-menthol ; therefore, the hy- droxyl-group in d-menthol probably stands in a closer structural relation to the tertiary hydrogen atom attached to the adjoining carbon atom than is the case in the molecule of 1-menthol. From this Wallach concludes that the isomerism in the menthyl- amine series is to be explained as a eis- and frans-isomerism ; 1 -menthylamine and 1-menthol are to be regarded as trans-com- pounds, and the dextro-isomers as cis-derivatives. The following formulas will illustrate this. ? H 3 CH S CH CH H 2 C CH 2 H 2 CJ CH 2 H a Q CH-NHj H 2 C ^CHNH, H^H, H 7 C 3 \ Trans-(l) -Menthylamine. Ois-( d) -Menthylamine. If, in the above formulas, the NH 2 group be replaced by the (OH) group, the corresponding menthols result, and* it will be iNegoworoff, Ber., 25, 162c; compare Ber., 25, 620. 368 THE TERPENES. observed that menthene can be formed more readily by the elimi- nation of water from cis-menthol than from trans-menthol. (a) l-( TRANS-) MENTH YL A MINE. 1-Menthylamine was first obtained pure by Andres and Andreef. It may be prepared by the following method. Ten grams of pure levo-menthonoxime are dissolved in seventy- five grams of absolute alcohol, and fifteen grams of sodium are added in small portions at a time to the boiling solution. The crystallization of sodium alcoholate is prevented by the occasional addition of absolute alcohol, the total amount added being about sixty cc. When the sodium is dissolved, the product is distilled with steam, and the receiving vessel is changed as soon as the distillate appears cloudy. The yield is nearly quantitative. After drying over potash, the amine boils at 209° to 210°; it has a disagreeable, strongly basic odor, and rapidly absorbs car- bonic anhydride from the air. It has the sp. gr. 0.86 and re- fractive index, n^ = 1.46058, at 20°; [a]^ = — 38.07°. 1-Menthylamine hydrochloride, C 10 H 19 NH 2 - HCl, is precipitated from ethereal solutions of the base as a white powder ; it dis- solves readily in alcohol and warm water. It does not melt at 280°, and at higher temperatures it may be distilled without de- composition. 1-Menthylamine hydrobromide, C 10 H 19 NH 2 - HBr, is more spar- ingly soluble in water than the hydrochloride, and crystallizes from water in needles. The hydriodide is more difficultly soluble than the hydrobromide. 1-Menthylamine nitrite, C 10 H 19 NH 2 - HN0 2 , is prepared from molecular proportions of the hydrochloride of the base and sodium nitrite ; on heating, it is converted into menthol, C 10 H I9 NH 2 HNO 2 = C 10 H 19 OH + H 2 0 + N 2 . 1-Formyl menthylamine, C 10 H 19 NITCOH, is best prepared by the distillation of the molecular quantities of the base and anhydrous formic acid. It is washed with water, and separates from methyl alcohol in splendid crystals, which melt at 102° to 103°. 1- Acetyl menthylamine, C 10 H 19 NH>COCH 3 , is obtained by the addition of the theoretical quantity of acetic anhydride to a solu- tion of the base in three times its volume of ethyl acetate ; a vigor- ous reaction takes place, and the acetyl derivative crystallizes from the cold solution. It is readily soluble in alcohol, ether and chloroform, but almost insoluble in petroleum ether ; it crystal- lizes from ethyl acetate, and melts at 145°. L-MENTHYXj trimethyl ammonium iodide. 369 1-Propionyl menthylamine, C 10 H 19 NH-COC 2 H 5 , is more readily soluble than the formyl and acetyl derivatives ; it crystallizes from ethyl acetate or acetone, and melts at 89°. 1-Butyryl menthylamine, C 10 H 19 NH-COC 3 H 7 , tends to separate from most solvents as an oil, but by recrystallization from acetone it is obtained in prisms, which melt at 80°. 1-Menthyl carbamide, C 10 H 19 *NH-CONH 2 , is obtained as an oil by the action of potassium isocyanate on 1-methylamine hydrochloride ; it solidifies after standing some time, and melts at 134° to 136°. 1-Menthyl phenylcarbamide, C 10 H 19 NH-CONHC 6 H 5 , results by the action of carbanile on the free base ; it crystallizes from alcohol, and melts at 140° to 141°. 1-Menthyl phenylthiocarbamide, C 10 H 19 NH-CS-NHC 6 H 5 , results when an ethereal solution of menthylamine is treated with the molecular amount of phenylthiocarbimide ; the reaction is ener- getic. It separates from ethyl acetate in lustrous crystals, and melts at 135°. 1-Benzylidene menthylamine, C 10 H 19 N=CHC 6 H 5 , is obtained by the action of benzaldehyde on menthylamine in a methyl alcoholic solution; it is crystallized from methyl alcohol, and melts at 69° to 70°. 1-Ortho-oxybenzylidene menthylamine, C 10 H 19 N = CH*C 6 H 4 OH, is produced in an analogous manner to the preceding compound ; it separates at first as an oil, which solidifies after washing with soda and cooling in a freezing mixture. It crystallizes in yellow needles, and melts at 56° to 57°. The nitroso-derivatives of the monoalkyl menthylamines are formed by treating one molecular proportion of menthylamine with one molecule of an alkyl iodide, liberating the free base from the resulting mixture, dissolving in hydrochloric acid, and treating with sodium nitrite. The resultant nitroso-derivatives of the secondary amines are distilled with steam, dried and rectified in vacuum. 1-Menthyl methylnitrosamine, C 10 H 19 N(NO) • CH 3 , is a yellow oil, boiling at 145° to 146° under 18 to 20 mm. pressure. 1-Menthyl ethylnitros amine, C^H^N^O) 1 C 2 H 5 , crystallizes from dilute methyl alcohol in colorless needles, melts at 52° to 53°, and boils at 155° to 156° (22 mm.). 1-Menthyl propylnitrosamine, C 10 H 19 N(NO)C 3 H 7 , boils at 159° to 161° (20 mm.). 1-Menthyl isobutylnitrosamine, C 10 H 19 N(NO)C 4 H 9 , crystallizes in white needles, melts at 52° to 53°, and boils at 160° to 161°. 1-Menthyl trimethyl ammonium iodide, C 10 H 19 N(CH 3 ) 3 I, crystal- lizes from water in large, colorless crystals, and melts at 190°. 24 370 THE TERPENES. Its alcoholic solution absorbs one molecule of iodine, forming a triiodide, C 10 H 19 N(CH 3 ) 3 I 3 , melting at 117° to 1 18°. 1-Menthyl trimethyl ammonium hydroxide, C 10 H 19 N(CH 3 ) 3 OH, is produced by digesting the preceding compound with moist silver oxide ; it is a colorless, crystalline, hygroscopic mass. On distil- lation under atmospheric pressure, it is decomposed into water, trimethylamine, and menthene, C 10 H 18 ; the latter boils at 170° to 171°, has the specific rotatory power, [a]^ = -f 89.307°, and does not yield a nitrosochloride. (b) d-(CIS- ) MENTH YL AMINE. When five grams of levorotatory menthone are heated with six grams of ammonium formate in sealed tubes at 190° to 200° for several hours, a mixture of the formyl derivatives of 1- and d-menthylamines is obtained. d-Formyl menthylamine is char- acterized by its great power of crystallization, and is more spar- ingly soluble than the isomeric 1-compound. Therefore, the con- tents of the tubes are washed out with ether and water, the ethereal solution is separated and allowed to evaporate slowly ; most of the d-formyl derivative separates in well defined crystals. On further evaporation of the mother-liquors, an oil is obtained, which is distilled in vacuum ; the fraction boiling at 180° to 183° at a pressure of 18 mm. to 20 mm. yields, on cooling, additional quantities of the d-formyl derivative, which may be completely freed from the mother-liquor by washing with petroleum ether. d-Formyl menthylamine is recrystallized from acetic ether. The yield amounts to fifty or sixty per cent, of the theoretical. Together with d-formyl menthylamine, of which considerable quantities remain in the oily mother-liquors, 1-formyl menthyl- amine and menthol are formed by the action of ammonium for- mate on levo-menthone ; the presence of the 1-base may be proved by its transformation into 1-menthylamine hydrochloride, which is insoluble in ether. Larger quantities of the d-base may be conveniently prepared by the following method. 1 In a 250 cc. round-bottom flask hav- ing a glass tube, one meter in length, sealed to it, ten grams of menthone and twelve grams of dry ammonium formate are heated over a direct flame for two days. The reaction-product separates into two layers, the lower, aqueous layer being light colored, the upper, a thick, brown oil. The latter is separated from the aqueous liquid, and is freed from unaltered menthone by steam distillation ; the residual oil is then distilled under reduced i Wallach and Werner, Ann. Chem., 300, 283. D-BUTYEYL MENTHYLAMINE. 371 pressure, the largest portion of which boils at 165° to 175° (20 mm.), and forms a colorless syrup ; on cooling, or after stand- ing for several days, the oil begins to solidify. The crystalliza- tion of the oil may be accelerated by rubbing up the syrupy mass with ether ; the crystals are filtered, recrystallized from ether, and consist of d-formyl menthylamine, melting at 117° to 118°. The 1-derivative is more soluble in ether, and only crystallizes after allowing the ethereal filtrate to stand during a considerable time. The formyl derivative of d-menthylamine, obtained by either of the above-mentioned methods, is saponified by heating with alcoholic potash, or better by boiling for two hours with concen- trated hydrochloric acid ; the resulting acid solution is concen- trated until crystallization commences, and the free base is sepa- rated by means of alkali. d-Menthylamine boils at 207° to 208°, has the specific gravity 0.857, the refractive index, n^ = 1.45940, and the specific rota- tory power, [0]^= -j- 14.71° ; in other properties the two men- thylamines are similar, but their derivatives differ very decidedly in melting point, solubility, etc. d-Menthylamine hydrochloride, C 10 H 19 NH 2 -HC1, can not be pre- cipitated from the ethereal solution of the base ; one hundred parts of ether at 15° dissolve twenty-two grams of this salt. It crystallizes from ether in splendid, transparent prisms, which, however, soon become opaque, and decompose. It is rather easily soluble in water and crystallizes from it in anhydrous plates, melting at 189°. d-Menthylamine hydrohromide, C 10 H 19 NH 2 -HBr, is sparingly sol- uble in ether, and crystallizes from water in fine, small needles, which melt at 225°. d-Menthylamine hydriodide, C 10 H 19 NH 2 'HI, is slightly soluble in water and ether, and melts at 270° with decomposition. d-Formyl menthylamine, C 10 H lg NH-COH, is prepared according to the above-described method ; it is also formed by heating the free base with formic acid at 200°. It separates from methyl al- cohol in very beautiful crystals, which melt at 117.5° ; it is spar- ingly soluble in ether and ethyl acetate, more difficultly in ligroine. d-Acetyl menthylamine, C 10 H 19 NH>COCH 3 , is obtained in the same manner as the corresponding 1-derivative ; it crystallizes from ethyl acetate in lustrous prisms, melts at 168° to 169°, and is readily soluble in ether and methyl alcohol. d-Propionyl menthylamine, C 10 H 19 NH COC 2 H 5 , melts at 151°. d-Butyryl menthylamine, C 10 H 19 NH COC 3 H 7 , melts at 105° to 106°, dissolves readily in methyl alcohol, sparingly in ethyl ace- tate, and very difficultly in ether and ligroine. 372 THE TERPENES. d-Menthyl carbamide, C 10 H 19 - NH • CONH 2 , crystallizes from dilute alcohol, and melts 155° to 156°. d-Menthyl phenylcarbamide, C 10 H 19 NHCONHC 6 H 5 , crystallizes from alcohol in fine needles, and melts at 177° to 178°. d-Menthyl phenylthiocarbamide, C 10 H 19 NH-CS NHC 6 H 5 , is pre- pared like the 1-derivative ; it separates from methyl alcohol in small crystals, having a diamond-like luster, and melts at 178° to 179°. d-Menthyl allylthiocarbamide, C 10 H 19 NHCSNHC 3 H 5 , is formed by the action of allylthiocarbimide on an ethereal solution of d-menthylamine ; it is very soluble in methyl alcohol, and crys- tallizes from a mixture of ether and ligroine in brilliant prisms, which melt at 110°. The analogous compound of the levo-series is an oil. d-Menthyl trimethyl ammonium iodide, C 10 H 19 N(CH 3 ) 3 I, crys- tallizes from hot water, and melts at 160° to 161°. d-Menthyl trimethyl ammonium hydroxide, C 10 H 19 N(CH 3 ) 3 OH, is prepared from the iodide by means of moist silver oxide. On heating, it is resolved into water, trimethylamine, and menthene ; the latter boils at 167°, and readily yields a nitrosochloride. d-Benzylidene menthylamine, C 10 H 19 N = CHC 6 H 5 , is obtained by the condensation of the base with benzaldehyde in an ethereal so- lution. It crystallizes in lustrous needles, which melt at 42° to 43°. d-Ortho-oxybenzylidene menthylamine, CLH.JST = CHCLILOH, ' JLU iy 6 4 * crystallizes from methyl alcohol in yellow needles, melting at 96° to 97°. When an aqueous solution of d-menthylamine hydrochloride is boiled with sodium nitrite, and the reaction-product is distilled with steam, a liquid results, which boils at 55° to 95° under a pressure of 20 mm.; on repeated fractionation, this oil is sepa- rated chiefly into low boiling portions from which menthene is obtained. It boils at 164° to 165°, has the sp. gr. 0.8175, and \a\ D = -f 55.44°. It forms a nitrosochloride, from which men- thene nitrolbenzylamine (m. p. 107° to 108°) is obtained. The higher boiling fractions contain a small quantity of menthol, and possibly a little menthone ; on oxidation with chromic acid, a product is formed which gives a semicarbazone (m. p. 184°), probably identical with 1-menthone semicarbazone. 1-Menthylamine is not converted into d-menthylamine at high temperatures, and the derivatives of the levo-base can not be transformed into those of the dextrorotatory amine. An investigation regarding the optical behavior of 1- and d-menthylamines, and of their salts and derivatives has been TERTIARY CARVOMENTHYLAMINE. 373 carried out by Wallach and Binz. 1 The following table presents the most important values obtained for the specific and molecular rotatory powers of these compounds. Solvent. [% Water a it —38.07° —35.66 —29.32 —24.72 —58.90° —68.15 —69.04 —69.77 Water <( Ether (i +14.71 +17.24 +13.83 + 11.79 + 8.34 + 5.26 +22.76 +32.94 +32.56 +33.28 + 15.94 +12.38 «Chloroform —83.37 —81.81 —76.53 —72.10 +54.03 +50.57 +45.14 +40.59 —152.27 —160.84 —161.15 —161.90 +98.68 +99.42 +95.05 +91.14 Wallach and Binz have also obtained values for the rotatory powers of these compounds in other solvents. 3. TERTIARY C AR VOMENTHYL AMINE t C 10 H 19 NH 2 . According to Baeyer, 2 tertiary carvomenthylamine results, together with regenerated carvomenthene, when tertiary carvomen- thyl iodide or bromide, formed by the addition of hydriodic acid or hydrobromic acid to carvomenthene, is treated in an ethereal solution with silver cyanide, and the resultant oil is saponified with potash. CH S CNH 2 (pH C 3 H 7 Tertiary carvomenthylamine. 1 Wallach arid Binz, Ann. Chem., 276, 317; compare Zeitschr. für physik. Chem., 12, 723. 2 Baeyer, Ber., 26, 2271. 374 THE TEKPENES. Tertiary carvomenthylamine hydrochloride is soluble in ether, and on evaporation of the solvent it remains as a syrup, which solidifies gradually. The platinochloride is a solid ; the gold double salt is precipitated as an oil, which soon solidifies, forming large, lustrous plates. The benzoyl derivative crystallizes in large needles, melting at 110° ; the phenylthiocarbamide forms prisms, which melt at 128°. 4. TERTIARY MENTH YL AMINE , C 10 H 19 NH 2 . Tertiary menthyl iodide or bromide, obtained by direct addition of hydriodic acid or hydrobromic acid to menthene, forms tertiary menthylamine when treated according to the method given under the preceding compound ; the yield is about ten per cent, of the theoretical. According to Baeyer, 1 this amine has the consti- tution : Tertiary menthylamine hydrochloride, C 10 H 19 NH a -HCl, is soluble in, and crystallizes from, ether; it melts at about 205°. The platinochloride crystallizes from alcohol in lustrous leaflets, and melts at 235°. The gold double salt forms an oil, which partially solidifies in needles. The phenylthiocarbamide crystallizes in leaflets, and melts at 118° to 119°. The benzoyl derivative separates in needles, which melt at 154.5°. AMIDO-DERIVATIVES OF PHELL ANDRENE . 1. AMIDOPHELLANDRENE, C 10 H 15 NH 2 . The so-called nitrophellandrene, C 10 H 15 NO 2 , obtained by Pesci by the action of ammonia on phellandrene nitrosite, may be con- verted into amidophellandrene by the following method (Pesci 2 ). Twenty grams of nitrophellandrene are dissolved in a mix- ture of sixty grams of glacial acetic acid and an equal volume of alcohol ; the solution is gradually treated with thirty grams 1 Baeyer, Ber., 26, 2270 and 2562. 2 Pesci, Gazz. Chim., 16, L, 228; Jahresb. Chem., 1884, 547. DIAMIDOPHELLANDRENE. 375 of zinc dust, and is heated on the water-bath at 70° after the first violent reaction has taken place. The reaction-product is diluted with water, neutralized with sodium hydroxide, and shaken with ether. The base is removed from the ethereal solu- tion by dilute hydrochloric acid, the acid solution is rendered al- kaline, and the amidophellandrene is again extracted with ether and purified by distillation with steam. It is an oily liquid, having a penetrating odor like that of conine ; it is moderately soluble in water, and absorbs carbonic anhydride with great readiness. Amidophellandrene sulphate, (C 10 H 15 NH 2 ) 2 -H 2 SO 4 , is rather spar- ingly soluble in cold water. The hydrochloride is crystalline, and easily soluble in alcohol and water. The platinochloride, (C 10 H 15 NH 2 -HCl) 2 PtCl 4 , forms yellow, hexagonal, microscopic phnWwhich are insoluble in water, but readily soluble in warm alcohol. The mercuric double salt is crystalline, and sparingly soluble. It has been mentioned that phellandrene nitrosite, and the com- pound, C 10 H 15 NO 2 , obtained by Wallach in the treatment of phellandrene nitrosite with sodium alcoholate, are both converted into optically active tetrahydrocarvylamine on reduction with sodium and alcohol. 2. DI AMIDOPHELLANDRENE , C 10 H 16 (NH 2 ) 2 . A diamine, C 10 H 16 (NH 2 ) 2 , was obtained by Pesci 1 by the reduction of phellandrene nitrosite. For the preparation of this base, phellandrene nitrosite is mixed with alcohol to form a thick paste, and is reduced by the addition of about ten per cent, of glacial acetic acid and zinc dust ; the zinc dust is added to the well cooled mixture in small por- tions at a time until the reaction is complete. The reaction- product is warmed at 40° to 50° for some time, then for one hour at 90,° and is diluted with water. The zinc is precipitated with hydrogen sulphide, filtered off, and the filtrate acidified with hydro- chloric acid ; this solution is evaporated to a small volume, made alkaline, and distilled with steam. The distillate is acidified with hydrochloric acid and evaporated, the residue is treated with potash, and the free base extracted with ether ; after drying the ethereal solution with solid potassium hydroxide, the ether is dis- tilled off, and the amine is rectified. Phellandrene diamine is a colorless, odorless liquid, having a strong refractive power; it boils at 209° to 214° with slight de- i Pesci, Gazz. Chim., 16, I., 229; Jahresb. Chem., 1885, 698. 376 THE TEKPENES. composition. It is readily soluble in water and alcohol, more sparingly in ether, chloroform and ligroine. The hydrochloride is crystalline but hygroscopic ; it yields a platinochloride, C 10 H 16 (NH 2 ) 2 -2HCl-PtCl 4 , which crystallizes in monoclinic prisms. The sulphate, acetate, nitrate and tartrate of phellandrene dia- mine are hygroscopic. OLEFINIC MEMBERS OF THE TERFENE SERIES. A. HYDROCARBONS. 1. MYRCENE, C 10 H J6 . Bay oil contains eugenol, methyl eugenol, chavicol, methyl chavicol, geranial and two hydrocarbons, C 10 H 16 . Mittmann 1 regarded these hydrocarbons as pinene and another terpene, prob- ably dipentene ; Power and Kleber, 2 however, proved that bay oil contains levorotatory phellandrene and a hydrocarbon, C 10 H 16 , which they called myrcene. This hydrocarbon has an open chain and may be designated as an aliphatic terpene. Myrcene is also found in the oil of sassafras leaves. 3 According to Power and Kleber, myrcene is obtained from the oil of bay by the following process. The oil is first shaken with a five per cent, solution of sodium hydroxide to remove phenols, and is then subjected to a fractional distillation in vacuum. (Myrcene is very readily polymerized by distillation under ordi- nary pressure.) About eighty per cent, of the oil from which the phenols are removed distills between 67° and 80° under a pressure of 20 mm. By repeated fractionation of this distillate in vacuo, a colorless liquid results, which boils at 67° to 68° under 20 mm. pressure; this liquid has a characteristic odor unlike that of the other terpenes. It has a specific gravity 0.8023 at 15°, con- siderably lower than that of the common terpenes. The coeffi- cient of refraction, n^, = 1.4673, is also remarkably small, and indicates that myrcene contains three double linkages. When a mixture of one part of myrcene, three parts of glacial acetic acid, and a small amount of dilute sulphuric acid is digested for three hours at 40°, according to Bertram's 4 method, the product contains an oil, having a lavender-like odor ; if this oil be saponi- fied with potash, and subsequently fractionated in a vacuum, a product is obtained which consists of unchanged myrcene, dipen- tene and linalool, C 10 H 17 OH. The presence of linalool is proved 1 Mittmann, Arch. Pharm., 1889, 529. 2 Pharm. Rund., New York, 1895, No. 13; Semi- Annual Report, Schim- mel & Co., April, 1895, 11. 3 Power and Kleber, Pharm. Review, 1896. «German Patent, No. 80,711. 377 378 THE TERPENES. by its conversion into the aldehyde geranial (citral), C 10 H 16 O, by careful oxidation, and by the characterization of the latter com- pound in the formation of the crystalline geranial-/9-naphthocin- chonic acid (see geranial, page 399). Since myrcene may be con- verted into linalool, C 10 H 17 OH, it bears the same relation to this alcohol as does camphene to isoborneol, and pinene or dipentene to terpineol (Power and Kleber). According to Barbier, 1 however, the alcohol, C 10 H 17 OH, ob- tained by Power and Kleber on hydrating myrcene as above men- tioned, is not identical with linalool (Barbier's " licareol "), but is isomeric with it ; Barbier designates it by the name myrcenol, C 10 H 17 OH. He describes it as a colorless, oily liquid boiling at 99° to 101° (10 mm.), and slowly undergoing polymerization ; it has the sp. gr. 0.9012 and the refractive index, n^= 1.47787, at 14.5°. Myrcenyl acetate, C 10 H 17 OOCCH 3 , is a colorless liquid boiling at 111° to 112° (10 mm.). When myrcenol is oxidized with a sulphuric acid solution of chromic acid, it yields acetone, laevulinic acid, and an aldehyde, C 10 H 16 O (not geranial), boiling at 110° (10 mm.). This aldehyde forms an oxime, C 10 H 16 vNOH, which boils at 148° to 150° (10 mm.), and is converted into the aldehyde by boiling with a solution of oxalic acid. The semi- carbazone is a crystalline powder, melting at 195° to 196°. When myrcenol is oxidized with a one per cent, permanganate solution and then with a chromic acid mixture, it yields laevulinic and succinic acids. According to Barbier, myrcene and myrcenol are to be repre- sented by the formulas, CHaS >C=CH— CH 3 — CH=C— CH=CH a . CH/ I CH 3 Myrcene. CHaN >C=CH— CH 2 — CH,— C(OH)— CH=CH 2 . CH/ I CH 3 Myrcenol. Characteristic additive products of myrcene can not be prepared because most reagents seem to polymerize it. Bromine is absorbed in a somewhat smaller quantity than corresponds to the addition of six atoms, but this is attributed to the polymerization of the hydrocarbon. Myrcene is easily oxidized by permanganate with the formation of succinic acid (Power and Kleber). iP. Barbier, Compt. rend., 182, 1048. ANHYDROGERANIOL. 379 Dihydromyrcene, 1 C 10 H 18 , is formed by reducing myrcene with alcohol and sodium ; it boils at 171.5° to 173.5°, has the specific gravity 0.7802, and the refractive index, n^ — 1.4501. On oxi- dation with permanganate, it yields laevulinic acid and a keto- glyeol, C 8 H 16 0 3 , which, on oxidation with chromic acid, gives rise to a diketone, C 7 H 12 0 2 . Cyclodihydromyrcene, 1 C 10 H 18 , is produced by treating dihydro- myrcene with a mixture of acetic and sulphuric acids ; it boils at 169° to 172°, has a sp. gr. 0.828, and a refractive index, np = 1.462. It unites with bromine, forming a dibromide (sp. gr. 1.524), and when oxidized it yields a hetonic acid, C 10 H lg O 3 . It should also be mentioned that the chemists of Schimmel & Co. 2 have isolated a hydrocarbon, C 10 H 16 , from basil oil, which boils at 73° to 74° (22 mm.), has the sp. gr. 0.794 at 22° and 0.801 at 15°, and the index of refraction, n i > = 1.4861. It is optically inactive, has an agreeable odor, and is termed ocimene. The properties of ocimene resemble those of myrcene, but it differs from the latter in its behavior towards oxygen ; it readily absorbs oxygen and becomes resinified. The examination of ocimene is not complete. 2. ANH YDRO GER ANIOL , C 10 H 16 . Anhydrogeraniol wasche first known representative of the class of olefinic terpenes. It is formed by heating geraniol, C 10 H 17 OH, in small portions at a time with twice its weight of acid potassium sulphate at 170°. When the reaction-product is distilled in a current of steam, an oil results, which, after purification by re- peated distillation over sodium, boils at 172° to 176° (uncorr.). This oil consists of anhydrogeraniol, C 10 H 16 ; it has a peculiar smell, a specific gravity 0.8232 and refractive power, n^ = 1.4835, at 20°. It yields a hydrocarbon, C 10 H 22 , by reduction, and unites with bromine, forming the compound, C 10 H 16 Br 6 (Semmler 3 ). No additional observations seem to have been made by Semmler regarding the behavior of this terpene. However, his assumption that it contains three double linkages, as indicated by its molecu- lar refraction, is in harmony with the fact that it combines with six bromine atoms or six atoms of hydrogen, forming addition- products. In the same preliminary publication, 3 Semmler mentions that similar olefinic terpenes are obtained from linalool and coriandrol by treatment with acid potassium sulphate as above described. 'Semmler, Ber., 34, 3122. 2 Schimmel & Co., Semi-Annual Report, April-May, 1901, 12. 3 Semmler, Ber., 24, 682. 380 THE TERPENES. 3. OLEFINI0 TERPENES IN OIL OF HOPS AND OIL OF ORIGANUM. Investigations of Chapman 1 on the oil of hops, and of Gilde- meister 2 on the oil of origanum from Smyrna indicate that these oils also contain olefinic terpenes. On fractional distillation both oils yield small quantities of a fraction which has the same boiling point as pinene, but is distinguished from the ordinary terpenes by its remarkably low specific gravity. Nothing further is known at present regarding these hydrocarbons. 4. LINALOLENE, C 10 H 18 . Linalolene is obtained by reducing linalool with sodium and alcohol, or better by heating equal weights of linalool and zinc dust in sealed tubes at 220° to 230° ; the resultant hydrocarbon is purified by distillation with steam, and by subsequent distilla- tion over sodium. It boils at 165° to 168°, has a specific gravity 0.7882 and a refractive power, n^ = 1.455, at 20° (Semmler 3 ). The values obtained for the specific and molecular refractive powers show that linalolene contains two ethylene linkages, and therefore belongs to the aliphatic series. When gently warmed with concentrated sulphuric acid, linalolene undergoes a trans- formation into an isomeric hydrocarbon, which boils at 165° to 167°, has the sp. gr. 0.8112 and the index of refraction, n^ = 1.4602, at 17°. Semmler considers this isomeride as a hydro- benzene derivative, and calls it cyclolinalolene. 5. HYDROCARBON, C 10 H 18 , OBTAINED FROM MENTHONYL- AMINE. When menthonylamine is treated with nitrous acid in the prep- aration of menthocitronellol, C 10 H 19 OH, a by-product is formed which contains a hydrocarbon, C 10 H 18 . It boils at 153° to 156°, has the specific gravity of 0.7545 at 15°, and a refractive power, n v = 1.4345 (Wallach 4 ). Chapman, Jour. Chem. Soc, 1894, I, 54; Ber., 28, 303, Ref. «Gildemeister, Arch. Pharm., 238, 182. 3 Semmler, Ber., 27, 2520. 'Wallach, Ann. Chem., 278, 317. LINALOOL. 381 B. OXYGENATED COMPOUNDS, (a) ALCOHOLS. 1. LINALOOL, C 10 H 17 OH. Morin 1 showed that the oil of linaloe contains an alcohol, C 1() H 17 OH, which Semmler 2 in the year 1891 identified as an aliphatic terpene alcohol ; he called it linalool. In the following year Barbier 3 submitted linalool, prepared from oil of linaloe, to a detailed investigation, and designated this alcohol as "licareol." Barbier at first doubted the identity of his " licareol " and lina- lool, but subsequently recognized that they were identical. 4 Linalool is very widely distributed in nature. Simultaneous with Semmler and Tiemann, 5 Bertram and Walbaum 6 found linalool and linaloyl acetate in the oil of bergamot. The alcohols, C 10 H 17 OH, which Semmler and Tiemann 3 called " aurantiol" and " lavendol" and which occur partially in a free condition and partially in the form of fatty acid esters in the oil of petitgrain and in lavender oil, are to be regarded as linalool (Bertram and Walbaum 6 ). In a subsequent publication, Tiemann and Semm- ler 7 assented to the views expressed by Bertram and Walbaum and added that the alcoholic constituent of the oil of neroli, the so-called "nerolol," is in all probability to be regarded as linalool. According to Reychler, linalool is also found in oil of ylang- ylang 8 and in oil of cananga 9 ; according to Gildemeister, 10 it occurs together with levorotatory linaloyl acetate in oil of limes (Citrus limetta Risso), and likewise in Smyrnan oil of origanum. Linaloyl acetate is found in sage oil (Salvia sclarea L.). 1-Linalool, partly free, partly as ester, forms a constituent of Palermo lemon oil, spike oil, thyme oil, 11 Russian spearmint oil, German 12 and French 13 basilicum oil, and sassafras leaf oil. 'Morin, Ann. Chim.Phys. [5], 25, 427. »Semmler, Ber., 24, 207. »Barbier, Compt. rend., 114, 674; Ber., 25, 463, Ref. 'Barbier and Bouveault, Compt. rend., 121, 168. 5 Semmler and Tiemann, Ber., 25, 1180. 6 Bertram and Walbaum, Journ. pr. Chem. [2], 45, 590. 'Tiemann and Semmler, Ber., 26, 2708. s Reychler, Bull. Soe. Chim. [3], 11, 407 and 576; Ber., 27, 751, Ref.; 28, 151, Ref. «Reychler, Bull. Soc. Chim. [3], ü,1045. '0 Gildemeister, Arch. Pharm., 233, 174. uLabbö, Bull. Soc. Chim., 19 [III.], 1009; Schimmel & Co., Semi-Annual Report, Oct., 1894, 57. ^Bertram and Walbaum, Arch. Pharm., 235, 176. ■ 3 Dupont and Guerlain, Compt. rend., 124, 300. 382 THE TERPENES. According to our present knowledge, linalool yields no crystal- line derivative which may be employed for the preparation of a chemically pure product from the above-mentioned ethereal oils. Therefore, linalool is separated by the fractional distillation of these oils ; but oils which contain esters of linalool, together with the free alcohol, must first be treated with alcoholic potash, and then rectified. The properties of linalool so prepared vary in certain respects according to its origin. These variations are rendered apparent by the following table. Linalool Obtained from, Lavender Oil (Bertram and Walbauni). 1 Bergamot Oil ( Bertram and Walbaum). 1 Linaloe Oil (Bertram and Walbaum). 1 Linaloe Oil (Semmler).2 Oil of Limes (Gilde- meister). 3 Oil of Origanum (Gilde- meister). 8 Boiling point. 197° to 197° to 197° to 195° to 198° to 197.8° to 199° 199° 200° 199° 199° 199° under under Specific gravity. 760 mm. 752 mm. 0.8725 at 0.8720 at 0.8770 at 0.8702 at 0.870 at 0.8704 at 15° 15° 15° 20° 15° 15° Refractive 1.4640 at 1.4629 at 1.4630 at 1.4695 at 1.4668 at 1.4633 at index, n/>. 20° 18° 20° 20° 20° 20° Angle of rotation — 10°35 / —16° —2° — 17°37 / — 15°56' (100 mm.). at 15° at 15° The difference in the properties of these various samples of lin- alool was at times explained by the supposition that they con- tained different, although closely allied, alcohols. Recently, however, all these alcohols have been regarded as identical, and the anomalies in their properties as being dependent on the pres- ence of impurities ; this view is rendered more probable by the fact that they exhibit exactly the same chemical behavior. If linalool, obtained from any of the above-mentioned oils, be oxi- dized with chromic acid, it is converted into an optically inactive aldehyde, geranial (citral), C 10 H 16 O, which is characterized by its transformation into cymene, and by the formation of the crystal- line geranial (citral)-/9-naphthocinchonic acid, melting at 198° to 199°. All alcohols of the formula, C 10 H 17 OH, having the properties given in the above table, are termed linalool if they are optically Bertram and Walbaum, Journ. pr. Chem. [2], ^5, 590. Temmler, Ber., 2Jf, 207. 3 Grildemeister, Arch. Pharm., 233, 174. LINALOOL. 383 levorotatory, and yield geranial on oxidation. If this definition of linalool be accepted, then an optically dextrorotatory alcohol, which Semmler 1 called " coriandrol" must be designated as dex- tro-linalool. This compound occurs in oil of coriander, and has the properties of linalool ; it boils at 194° to 198°, has the spe- cific gravity 0.8679 and refractive index, n^ = 1.4652, at 20°, and is converted into geranial by oxidation ; its optical rotation is reported as \a\ D = + 13° 19' and + 15° V. It is of course possible with the' increase of knowledge respect- ing this group of compounds, that the various alcohols, which we designate at present as linalool, will be distinguished from one another, and characterized as chemical individuals. Theoretic- ally, numerous isomerides of geranial may be predicted. As Tie- mann and Semmler have indicated, a transposition of the ethylene linkages may take place in such substances by treatment with certain reagents, and this has been especially observed by Fittig ; hence, the formation of the same geranial from isomeric alcohols could be explained by the acceptance of a similar hypothesis. One observation seems to point to the fact that an intramolecular change of this nature takes place in linalool. When linalool is heated with acetic anhydride, it is rendered inactive, and is con- verted into the acetyl derivative of the isomeric, inactive alcohol, geraniol. Geraniol boils 30° higher than linalool, and, there- fore, can not have the same connection with the latter compound as dipentene with limonene. In consideration of the results ob- tained by the oxidation of these alcohols, Tiemann and Semmler 2 represent the transformation of linalool into geraniol by the fol- lowing formulas : CH 3 — C =CH— CH 2 — CH S — C (OH)— CH = CH 2 CH 3 CH S Linalool (dimethyl-2-6-octadiene-2-7-ol-6 ). CH 3 — (J = CH — CH 2 — CH, — C = CH-CH 2 OH. CH S CH 3 Geraniol ( dimethyl-2-6-octadiene-2-6-ol-8 ) . According to more recent investigations by Barbier, 3 this for- mula for linalool represents the constitution of myrcenol, and 'Semmler, Ber., 24, 206; compare Kawalier, Jahresb. Chem., 1852, 624, and Grosser, Ber., 14, 2485. «Tiemann and Semmler, Ber., 28, 2126. »Barbier, Bull. Soc. Chim., 25 [III.], 828. 384 THE TERPENES. Barbier therefore suggests that linalool is stereoisomeric with geraniol ("lemonol"), and is to be represented by the formula : CH 3 -C =CH-CH 3 -CH 2 -C =CH— CH 3 OH. CH 3 CH 3 Linalool. According to Barbier, the compound previously regarded as pure linalool is a mixture of levo-terpineol, active myrcenol and unsaturated ethers of the formula, C 10 H lg O ; and since linalool has not been obtained free from these substances, the optical rota- tion of the pure alcohol is not at present known. Barbier re- gards pure linalool as inactive, and since the oxidation products of linalool are identical with those of geraniol, he considers that all the reactions of linalool are more readily explained by his formula. According to Tiemann, 1 a fairly pure linalool, free from ter- penes, may be obtained from the essential oils by the following process. Sodium is added to the crude linalool contained in a retort, and the liquid is heated under reduced pressure as long as the sodium continues to be dissolved ; after cooling, the unchanged metallic sodium is removed, the sodium salt of linalool is suspended in dry ether, and treated with succinic, or, better, phthalic anhy- dride. After standing for several days, the liquid is agitated with water, which dissolves the linaloyl sodium phthalate, while any unchanged linalool or linalolene remains in the ether ; the aqueous solution is repeatedly washed with ether, the solution is acidified, and again extracted with ether. The resulting linaloyl acid phthalate is hydrolyzed with alcoholic potash, and the puri- fied linalool is extracted with ether. An inactive linalool may be artificially prepared by heating geraniol with water in an autoclave for some time at 200° j it boils at 198° to 200° (753 mm.), and has the sp. gr. 0.877 at 15°. 2 Another method of preparing inactive linalool consists in treating geraniol with hydrochloric acid, and saponifying the re- sultant, isomeric chlorides, C I0 H 17 C1, with alcoholic potash ; some geraniol is regenerated, and about fifty per cent, of inactive linalool is obtained (Tiemann 3 ). According to Stephan, 4 a third method of converting geraniol into inactive linalool consists in 'Tiemann and Krüger, Ber., 29, 901; Tiemann, Ber., SI, 837. 2 Schimmel & Co., Semi-Annual Report, April, 1898, 27. 3 Tiemann, Ber., 81, 832. «Stephan, Journ. pr. Chem., 60 [II.], 252. LINALOOL. 385 passing steam into an aqueous solution of sodium geranyl phtha- late ; some geraniol is also regenerated. It is reported that levo-linalool may be converted into dextro- linalool by the influence of acid reagents 1 ; thus, this transforma- tion is said to take place on heating a solution of linaloyl acid phthalate, and during the preparation of linaloyl acetate by the action of acetic and dilute sulphuric acids on linalool. Linalool absorbs four atoms of bromine. When reduced with sodium and alcohol, or when heated with zinc dust at 220° or 230°, it is converted into linalolene, C 10 H 18 (Semmler). By the action of hydrochloric acid on linalool, water is eliminated, and a mixture of liquid chlorides, C 10 H 18 C1 2 , results ; they decompose when dis- tilled in vacuum (Bertram and Walbaum). According to Barbier, 2 when this mixture of chlorides is heated with potassium acetate and glacial acetic acid, terpenes, geranyl acetate and geraniol are formed. The action of dehydrating agents on linalool has been studied by Bertram and Walbaum. Water may be removed by acid potassium sulphate or by dilute sulphuric acid. When linalool is heated gently with formic acid of sp. gr. 1.22, a somewhat violent reaction takes place, and water is very readily separated with the formation of terpinene and dipentene ; this reaction is worthy of special notice, since by means of it the first transformation of an aliphatic compound into a true terpene, C 10 H 16 , was effected. Ac- cording to Semmler, aliphatic terpenes may also be obtained from linalool, but nothing definite has been published regarding such compounds. (See anhydrogeraniol.) When formic acid is allowed to act on levo-linalool at a tem- perature below 20°, fifty per cent, of the linalool is converted into dextro-terpineol ; in the same manner, formic acid converts dextro- linalool (coriandrol) into levo-terpineol (Stephan 3 ). When 1-linalool is warmed with acetic acid, some d-terpineol is produced. Cold acetic acid does not act upon it, but if a solution of linalool in three times its weight of acetic acid be treated with one half a per cent, of sulphuric acid at a temperature below 20°, about forty-five per cent, is changed into ^-terpineol, and ten per cent, into geraniol (Stephan 3 ). Hydrogen peroxide converts linalool into a crystalline com- pound, melting at 110° to 111°; this substance has been shown to 'Schimmel & Co., Semi-Annual Report, Oct., 1896, 85; compare with Charabot, Bull. Soc. Chim., 21, 549. s Barbier and Bouveault, Bull. Soc. Chim., 15 [III.], 594. »Stephan, Journ. pr. Cheiu., 58 [II.], 109. 2-5 386 THE TERPENES. be identical with terpine hydrate, the formation of which is prob- ably due to the presence of a mineral acid impurity in the reagent (Bertram and Walbaum). Terpine hydrate is almost quantitatively formed, when linalool is agitated with five per cent, sulphuric acid for several days. 1 Chromic acid oxidizes linalool into the aldehyde geranial (citral). The oxidation sometimes proceeds further, yielding oxida- tion products of geranial, as methyl heptenone, laevulinic acid, etc. Tiemann and Semmler 2 obtained rather remarkable results in the oxidation of linalool. By successive treatment with potas- sium permanganate and chromic acid, they accomplished quite readily a decomposition of this alcohol into acetone, laevulinic acid and oxalic acid. They concluded, therefore, that linalool contains the grouping, C(CH S ) 2 = CH-CH 3 -CH 2 — C(CH 3 )=; and considering that it must also contain an asymmetric carbon atom, they derived the formula of linalool which has already been presented. The alcohol obtained from coriander oil, which must be desig- nated as dextro-linalool, yields compounds, C 10 H 17 C1 and C 10 H 17 I, when treated with hydrochloric and hydriodic acids ; these sub- stances are oils which can not be distilled. When dextro-linalool is oxidized with permanganate, it is converted into a ketone, C 10 H 16 O, carbonic anhydride, acetic acid and a gelatinous acid, having the constitution C 6 H 10 O 4 (Grosser 3 ). Linaloyl acetate, C 10 H 17 OCOCH 3 , is found in many ethereal oils, especially in the oil of orange blossoms and in the oil of bergamot, whose odor is dependent on it. It is formed when myrcene is treated with a mixture of glacial acetic and sulphuric acids (Power and Kleber 4 ). In order to prepare it, linalool is boiled with acetic anhydride for several hours, the product is washed with water and soda solution, and the ester distilled with steam. The terpenes which result during its preparation are separated by fractional distil- lation in vacuum (Bertram and Walbaum). Linaloyl acetate has a strong odor of bergamot, and boils and decomposes at 220° when distilled under ordinary pressure. It boils at 105° to 108° under a pressure of 11 mm., and has the i Tiemann and Semmler, Ber., 28, 2137. «Tiemann and Semmler, Ber., 28, 2126. sGrosser, Ber., U, 2494 and 2497. "Power and Kleber, Pharm. Rundsch, 1895, No. 13; A. Hesse, Journ. pr. Chem., 64 [IL], 245. GrEBANIOL. 387 specific gravity 0.912 at 15° ; [a]^ = - 6° 25'. Alcoholic pot- ash changes it into linalool. Pure linaloyl acetate may be prepared from sodium linaloolate and acetic anhydride; it boils at 96.5° to 97° under 10 mm. pressure (Hesse). If the acetate be prepared from levo-linalool by means of a mixture of glacial acetic and sulphuric acids, dextro-Iinaloyl acetate is obtained; this yields dextro-linalool when saponified (Gildemeister Linaloyl propionate, C 10 H 17 OCOC 2 H 5 , is a fragrant oil, which boils at 115° under 10 mm. pressure. It occurs naturally in lavender oil. Linaloyl butyrate occurs in lavender oil, and the valerianate is contained in lavender oil and sassafras oil. It is to be noted that the esters of linalool, which are prepared synthetically by heating linalool with acid anhydrides, are not chemically pure compounds ; they consist largely of the esters of linalool, together with some esters of geraniol and terpineol, and are usually optically inactive or slightly dextrorotatory. The naturally occurring esters are levorotatory. 2. GERANIOL, C 10 H 17 OH. Geraniol is an alcohol closely related to linalool, but is distin- guished from it by its optical inactivity and by its higher boiling point (linalool boils at 197° to 200°, geraniol at 229° to 230°). The conversion of linalool into geraniol was first observed by Barbier. 2 This chemist found that the boiling point of linalool increases and its optical rotatory power decreases when it is heated with acetic anhydride at 120° for a long time ; the resultant alco- hol, having a rose-like odor, was thought to be different from geraniol, and was called " licarhodol." Bouchardat 3 at once ex- pressed the opinion that this licarhodol was identical with geraniol. The correctness of Bouchardat's statement was conclusively proved by Bertram and Gildemeister 4 by the isolation of the cal- cium chloride compound of geraniol from Barbier' s licarhodol. i Gildemeister, Arch. Pharm., 233, 174; German Patent, No. 80,711; com- pare with Tiemann and Semmler, Ber., 25, 1184 and 1187; Bertram and Walbaum, Journ. pr. Chem., 45 [II.], 598. 2 Barbier, Compt. . rend., 116, 1200; Ber., 16, 490, Ref. 3 Bouchardat, Compt. rend., 116, 1253; compare Barbier, Compt. rend.. Ill, 122. 'Bertram and Gildemeister, Journ. pr. Chem. [2], 49, 185; compare Stephan, Journ. pr. Chem. [2], 58, 109; Schimmel & Co., Semi-Annual Re- port, April, 1898, 33. 388 THE TERPENES. Tiemann and Seramler 1 also confirmed Bouchardat's view, and Barbier and Bouveault 2 have admitted its accuracy. Geraniol is widely distributed in nature. Indian oil of geran- ium and palmarosa oil contain ninety-two per cent, of geraniol as shown by the experiments of Jacobsen 3 and, more recently, by those of Semmler. 4 It has also been found in pelargonium oil (African geranium oil) by Gintl, 5 and in the oil of citronella by Schimmel & Co. 6 It occurs in the oil of Eucalyptus maculata, var. citriodora, and occurs, together with linalool, in lavender oil, lemon grass oil and ylang-ylang oil. It is also found in small quantities in neroli and petitgrain oils, oil of spike, lignaloe oil, and sassafras oil. According to Smith, 7 the oil from the fresh leaves and branchlets of Eucalyptus macarthuri contain sixty per cent, of geranyl acetate, 10.64 per cent, of free geraniol, as well as some eudesmol. Of especial interest, however, is the fact that the greatest part of the alcoholic constituents of Turkish and German oil of rose consists of geraniol (Bertram and Gildemeister 8 ). In an investigation of the oil of rose, Eckart 9 discovered an alcohol, CLH lo 0, to which he gave the name " rhodinol." Mark- ownikoff and Iieformatzky 10 examined rose oil and came to the conclusion that it contained an alcohol, C 10 H 20 O, which they called "roseol " ; Barbier 11 rejected this conclusion, and confirmed Eckart's observations. Tiemann and Semmler 1 further de- termined that "rhodinol" C 10 H 16 O, which is obtained by the oxidation of Eckart's "rhodinol," C 10 H 18 O, is identical with garanial, C 10 H 16 O. The conclusive proof that rose oil contains geraniol was given by Bertram and Gildemeister by the isolation of the calcium chloride compound of geraniol from rose oil. More recent investigations have proved that rose oil 12 and the ethereal 'Tiemann and Semmler, Ber., 26, 2708. Barbier and Bouveault, Compt. rend., 121, 168. sjacobsen, Ann. Chem., 157, 232. «Semmler, Ber., 23, 1098. sGintl, Jahresb. Chem., 1879, 941. e Semi-Annual Report of Schimmel & Co., Oct., 18.9.?, and German Patent, No. 76,435; Ber., 27, 953, Ref.; compare Journ. pr. Chem. [2], 49, 191, and Dodge, Amer. Chem. Journ., 18S9, 456; Ber., 23, 175, Ref. 'H. G. Smith, Chem. News, 83, 5. »Bertram and Gildemeister, Journ. pr. Chem. [2], 49, 185; Gildemeister and Stephan, Arch. Pharm., 234, 321. s Eckart, Arch. Pharm., 229, 355. luMarkownikoff and Reformatzky, Journ. pr. Chem. [2], 48, 293; Ber., 27, 625, Ref. ii Barbier, Compt. rend., 117, 177 and 1092. i*Dupont and Guerbain, Compt. rend., 123, 700. GERANIOL. 389 oils of the genus Pelargonium contain geraniol, C 10 H 18 O, together with considerable quantities of another alcohol, citronellol, C 10 H 20 O. The terpene alcohol " reiiniol," prepared by A. Hesse 1 from Reunion geranium oil by means of its camphoric acid ester, has been shown to be a mixture 2 of geraniol, C 10 H l8 O, and citronellol, C 10 H 20 O - Erdmann and Huth 3 suggested that the name " rhodinol " be substituted for that of geraniol ; this suggestion, however, can not be accepted. Barbier and Bouveault 4 obtained an alcohol from the volatile oil of Andropogon schcenanthus; they considered it an individual chemical compound, and called it " lemonol." Bertram and Gil- demeister 5 have proved that this " lemonol " is a mixture, contain- ing considerable quantities of geraniol. Very different opinions have been expressed from time to time by different chemists regarding the constituents of the above-men- tioned essential oils, and the nature of the alcohols obtained from them. The use of different names for geraniol and citronellol, or for mixtures of these two alcohols has led to considerable con- fusion in the study of these compounds and their derivatives. It must suffice here merely to note that the recent investigations, especially those of Bertram and Gildemeister, 6 chemists of Schim- mel & Co., Leipzig, have practically proved that geraniol, C 10 H 18 O, is identical with " lemonol " (Barbier and Bouveault), and with " rhodinol " (Erdmann and Huth, and Poleck) ; citronellol, C 10 H 20 O (Tiemann and Schmidt) is identical with "rhodinol" of Barbier and Bouveault and with " r6uniol " (Hesse, Naschold) ; Eckart's " rhodinol " is a mixture of geraniol and citronellol, and the same may be said of " roseol " (Markownikow) ; " licarhodol " (Barbier) is a mixture of about eighty-five parts of geraniol and fifteen parts of dextro-terpineol. ■A. Hesse, Journ. pr. Chem., 50 [IL], 474; 53 [IL], 23; Wallach and Naschold, Naschold's Inaug. Diss., Göttingen, 1896. 2 Schimmel & Co., Semi- Annual Report, April, 1895, 37 and 63; Tiemann and Schmidt, Ber., 29, 903. s Erdmann and Huth, Journ. pr. Chem., 53 [II], 42; 56 [II], 1; Poleck, Ber., 31, 29; Journ. pr. Chem., 56 [IL], 515; Bertram and Gildemeister, Journ. pr. Chem., 56 [IL], 506. «Barbier and Bouveault, Compt. rend., 118, 1154 and 1208; 119, 281 and 334; 122, 393; Bull. Soc. Chim., 15 [III.], 594; Barbier, Compt. rend., 126, 1423; Tiemann, Ber., 31, 2989; Barbier, Bull. Soc. Chim., 21 [IL], 635. 5 Bertram and Gildemeister, Journ. pr. Chem., 53 [IL], 225; Schimmel & Co., Semi-Annual Report, April, 1898, 33. 6 Schimmel & Co., Semi- Annual Report, April, 1896, .37; Oct., 1896, 85, 87 and 90; April, 1897, 32; Oct., 1897, 67; Oct., 1898, 55. 390 THE TERPENES. In order to prepare geraniol, the oils which contain large quan- tities of this alcohol are treated with alcoholic potash to remove esters, and are then fractionated in vacuo. The resulting gera- niol, however, generally contains impurities. The method for the purification of this product depends on the property observed by Jacobsen 1 that geraniol combines with calcium chloride. Ac- cording to Bertram and Gildemeister, 2 the crude geraniol is care- fully dried and intimately mixed with an equal amount of freshly dried and finely pulverized calcium chloride ; the mixture is al- lowed to stand in a desiccator at a temperature of — 4° to — 5° for twelve to sixteen hours. The resultant, more or less tough, mass is rubbed up with anhydrous benzene or petroleum ether, and filtered with the pump. The substance remaining on the filter is again mixed with benzene and filtered, the same process being repeated for a third time; the product is then decomposed with water. The oil which separates is washed with water and distilled, the geraniol boiling at 228° to 230°. As a rule the separation of geraniol by this method is only applicable when the ethereal oil contains at least twenty-five per cent, of geraniol. Chloride of magnesium, and calcium or magnesium nitrate also form crystalline additive compounds with geraniol, and may be used in place of calcium chloride. Several other methods 3 have been proposed for the separation of geraniol from mixtures with terpenes, etc., depending on the pro- duction of an acid geranyl ester by the action of succinic, or, pref- erably, phthalic anhydride on the sodium salt of crude geraniol, or by heating geraniol with phthalic anhydride on the water- bath. This acid ester or its sodium salt (prepared from the pure silver salt) is saponified with alcoholic potash, and a very pure geraniol is obtained. These methods have no great superiority over the calcium chloride process. Properties. — Geraniol is an optically inactive alcohol, which has a very pleasant odor of roses, and boils at 229° to 230° under atmospheric pressure and at 120.5° to 122.5° under a pressure of 17 mm. Its specific gravity at 15° is 0.8801 to 0.8834, according to its origin ; the refractive power is n^ = 1.4766 to 1.4786. The specific gravity of geraniol increases rapidly when it is allowed to stand in the air (Tiemann and Semmler 4 ). Jacobsen, Ann. Chem., 157, 232. 2Semi-Annual Report of Schimmel & Co., 1895, 38. "Tiemann and Krüger, Ber., 29, 901; Haller, Compt. rend., 122, 865; Erdmann, Journ. pr. Chem., 56 [II.], 17; Flatau and Labb6, Compt. rend., 126, 1725; Bull. Soc. Chim., 19 [III.], 635. 4 Tiemann and Semmler, Ber., 26, 2711. GERANYL. BEOMIDE DIHYDROBROMIDE. 391 Jacobsen recognized geraniol as an alcohol, and prepared ger- anyl chloride, C 10 H 17 C1, geranyl bromide and iodide by the action of the halogen hydrides on geraniol ; he described these com- pounds as oils which could not be distilled, and further stated that their halogen atoms could be replaced by sulphur, oxygen and acid radicals. According to Reychler, 1 when geraniol is saturated with hy- drogen chloride, the compound, C 10 H 18 C1 2 , is formed ; when this substance is boiled with water, it yields a product intermediate be- tween C 10 H 18 C1 2 and C 10 H 18 O. Isomeric chlorides, C 10 H 17 C1, are probably produced by the action of hydrogen chloride on geraniol ; they are converted into geraniol and linalool by the action of alcoholic potash. 2 Geranyl bromide dihydrobromide, 3 C 10 H 17 Br-2HBr, is formed by the action of hydrobromic acid on geraniol in glacial acetic acid solution ; it decomposes on distillation. Silver acetate converts it into geranyl acetate and a diacetate of a glycol, C 10 H 18 (OH) 2 . According to Semmler, geraniol absorbs four atoms of bromine or iodine. The conversion of geraniol into the isomeric linalool was men- tioned under linalool. On the other hand, linalool may be con- verted into a mixture of geraniol and dextro-terpineol or its ace- tate (Barbier's " licarhodol" ) by heating with acetic anhydride. 4 On heating geraniol with water in an autoclave at 240° to 250°, it is decomposed into hydrocarbons (dipentene). 3 Geraniol is more stable towards acids than linalool. Boiling acetic anhydride converts it quantitatively into geranyl acetate; no terpineol is formed during this reaction. Acetic acid con- taining one to two per cent, of sulphuric acid converts it into terpineol. 5 Formic acid acts on geraniol at 0° to 5° yielding geranyl formate; on warming, terpinene is produced; at 15° to 20°, however, the product consists chiefly of terpinyl formate, which yields terpineol (m. p. 35°) on hydrolysis (Stephan). When geraniol is shaken with a five per cent, sulphuric acid for several days, terpine hydrate is formed. 6 1 Reychler, Bull. Soc. Chem., 15 [III.], 364; Barbier and Bouveault, Bull. Soc. Chim., 15 [III.], 594. «Tiemann, Ber., SI, 808. »Naschold, Inaug. Diss., Göttingen, 1896. H. Erdmann, Journ. pr. Chem., 56 [IL], 1; Flatau and Labbe\ Compt. rend., 126, 1725. GERANIAL. 397 an aldehyde, C 10 H 16 O, and that the characteristic odor of oil of lenon is due to this aldehyde, which was termed citral. 1 Semmler 2 had also obtained an aldehyde, C 10 H 16 O, in the oxida- tion of geraniol ; he then made a careful investigation of citral and showed that his aldehyde, called geranial, was identical with citral, heice the two names, citral and geranial, have been employed to designate this compound. Although the name citral is historically correct, nevertheless geranial is to be preferred in most instances since it indicates that this compound is the aldehyde correspond- ing to geraniol. . Geranial has been found in bay oil (Power and Kleber ), in citronella fruit oil, in cedro oil, in eucalyptus oils of Backhousia citriodora and Eucalyptus staigeriana, in lemongrass oil, Japanese pepper oil of Xanlhoxylum piperitum DC. (Schimmel & Co.), and in the oil of orange peel (Semmler). It also occurs in mandarin oil, West Indian limette oil, verbena oil, balm oil, pimenta oil, and the oil of sassafras leaves. Geranial may be isolated from the ethereal oils by means of its crystalline acid sodium sulphite compound. It is prepared from geraniol by the following method (Semmler 4 ). Fifteen grams of geraniol are added, all at once, to a solution often grams of potassium dichromate in 12.5 grams of concen- trated sulphuric acid and one hundred cc. of water ; the mixture is at first well cooled, and afterwards allowed to become warm, and vigorously shaken for half an hour. The reaction-product is then made slightly alkaline and distilled in a current of steam ; the resulting oil is mixed with a solution of acid sodium sulphite, and allowed & to remain for twenty-four hours. The crystals are then collected, pressed between filter-paper, and decomposed with soda. Properties.— Geranial has a specific gravity of 0.8972 at 15° or 0 8844 at 22° ; at the same temperatures its refractive index is n»= 1.934, and = 1.486116. It boils at 110° to 112° at 12 mm. pressure, 117° to 119° at 20 mm., and 120° to 122° at 23 mm. Under atmospheric pressure it boils with slight decom- position at 228° to 229°. Geranial is a mobile, slightly yellowish oil, having a penetrating lemon-like odor ; it is optically inactive (Tiemann and Semmler *). It has the characteristic properties of an aldehyde, reducing a sil- ver solution, and coloring a fuchsine-sulphurous acid solution. !For the history of citral, compare Tiemann, Ber., 31, 3278. i Semmler, Ber., 23, 2965; U, 201. sPower and Kleber, Pharm. Rundsch., 1895, No. 13. 'See also Tiemann, Ber., 31, 3311. ^Tiemann and Semmler, Ber., 26, 2708. 398 THE TERPENES. . Ifc has been mentioned that, on oxidation with chromic acid, hnalool suffers an intramolecular transformation into geraniol, and then yields geranial. The latter compound has also been syn- thetically prepared by Tiemann 1 by the distillation of a mixture of the calcium salts of formic and geranic acids. Geranial forms a liquid, additive compound with four atoms of bromine.^ It is very sensitive towards acids. According to Semmler, 2 geranial is characterized by the great readiness with which it loses water and is converted into cymene, when heated with twice its weight of potassium bisulphate for twenty minutes at 170° ; dilute sulphuric acid also changes it into cymene. Al- kalis 3 also decompose geranial ; when treated with caustic soda, it suffers a partial decomposition into methyl heptenone, CH o' acetaldehyde, and resinous substances. Geranial is converted into the corresponding primary alcohol, geraniol, on reduction. 4 The behavior of geranial towards sodium bisulphite has been studied by Tiemann and Semmler. 5 The normal additive com- pound of geranial and sodium bisulphite, C 9 H 15 -CH(OH)-SO.Na is formed when geranial (100 parts), sodium thiosulphate (100 parts), water (200 parts), and acetic acid (25 parts) are shaken at a low temperature ; it is decomposed by dissolving in water, but may be recrystallized from methyl alcohol containing some acetic acid ; a quantitative yield of geranial is never obtained from this compound on treatment with sodium carbonate or caustic soda. A stable dihydrosulphonie acid derivative of geranial is produced when the normal compound is submitted to steam distillation, or is boiled with chloroform, one-half of the geranial being regener- ated. A labile dihydrosulphonie acid derivative, C 9 H 17 (S0 3 Na) • CHO, results when geranial is agitated with sodiun/sulphite, and the sodium hydroxide, which is liberated, is neutralized. It is also formed when the normal crystallized compound is allowed to stand for some time with an excess of an acid sulphite solution. It is readily soluble in water, and does not yield geranial on treatment with alkali carbonates, but is converted into the aldehyde by an excess of caustic alkalis. It reacts with semicarbazide, formino- sodium geranial semicarbazone dihydrodisulphonate. In the puri- fication of geranial, it is sufficient to form the labile disulphonic derivative in solution, and then to decompose it with alkali. Sodium geranial hydrosulphonate results on shaking the labile di- 1 Tiemann, Ber., 31, 827. Temmler, Ber., 28, 2965; 24, 201; Tiemann, Ber., 32, 107 aVerley, Bull. Soc. Chim., 17 [III.], 175; Tiemann, Ber., 82, 107. 4 Tiemann, Ber., 31, 828. sTiemann and Semmler, Ber., 26, 2708; Tiemann, Ber., 31, 3297. GERANYL PHENYLHYDRAZONE. 399 hydrosulphonate with geranial ; it is soluble^ in methyl alcohol, and is readily decomposed by sodium hydroxide. This peculiar behavior of geranial towards sodium bisulphite solution is obviously similar to the reactions which have been ob- served with various unsaturated aldehydes and ketones, and which have been studied in detail by Müller 1 in the case of acrolein, and by Heusler 2 and by Tiemann 3 regarding cinnamic aldehyde. Geranial- (citral-) /3-naphthocinchonic acid, C^H^NO^ — This de- rivative of geranial, first prepared by Doebner, 4 is very charac- teristic, and especially well adapted for the detection of small amounts of geranial in ethereal oils. According to this chemist, aldehydes may be condensed with pyroracemic acid and /9-naph- thylamine, yielding alkyl-/9-naphthocinchonic acids ; the geranial derivative is obtained according to the equation : C 9 H 15 CHO + CH3COCOOH + C 10 H 7 NH 2 = 2H 2 O + H 3 + [ CC 9 H 15 C COOH. It is prepared by boiling an alcoholic solution of twenty grams of geranial, twelve grams of pyroracemic acid and twenty grams of /3-naphthylamine for three hours ; fourteen grams of the compound are produced. It crystallizes from dilute alcohol in lemon-yellow leaflets, which contain one-half molecule of water of crystallization, and melt at 197°. 5 The hydrochloride of geranial- /?-naphthocinchonic acid crystallizes from alcohol in orange-yellow needles. Geranyl phenylhydrazone, C 10 H 16 N 2 HC 6 H 5 , is an oil, which de- composes when distilled in a vacuum (Tiemann and Semmler). The anilide, C 10 H 16 = NC 6 H 6 , is formed by heating geranial and aniline at 150°; it is a yellow liquid, boiling at 200° under a pressure of 20 mm. 'Müller, Ber., 6, 1441. «Heusler, Ber., 2J h 1805. «Tiemann, Ber., 31, 3297. «Doebner, Ber., 27, 352 and 2020; 31, 1888 and 3195; compare also Ber., 31, 3331; 32, 115. sThe melting point is frequently reported at 200° or slightly above this point. 400 THE TEßPENES. Dry ammonia also reacts with geranial, yielding an oil which can not be distilled without decomposition in a vacuum. Geranialoxime, C 10 H 16 NOH, is formed by the action of the molecular amounts of hydroxylamine hydrochloride and soda on an alcoholic solution of geranial. It is a yellow oil, boils at 143° to 145° under 12 mm. pressure, has a specific gravity of 0.9386 at 20° and an index of refraction, n^ = 1.51433. When the oxime is distilled at atmospheric pressure, water is removed and the nitrile of geranic acid is produced, together with an amine which has not been carefully investigated (Tiemann and Semmler). Geranial semicarbazones, C 10 H X = N • NHCONH . — A number of isomeric semicarbazones appear to have been obtained from geranial by dhTerent investigators. Wallach 1 mentions two such derivatives, melting at 150° and 160°; Tiemann and Semmler 2 describe a semicarbazone, melting at 130° to 135°. Barbier and Bouveault 3 state that the fraction of the oil of lemongrass (b. p. 107° to 110° at 10 mm.) yields a semicarbazone, melting at 171° ; it forms white crystals and is very sparingly soluble in boiling alco- hol. The fraction of the same oil, boiling at 110° to 112° (10 mm.), gives three isomeric derivatives, melting at 171°, 160° and 135° respectively. According to more recent investigations by Tiemann,* ordinary geranial yields two isomeric semicarbazones ; one is produced in large amount and melts at 164°, and the other is formed in small quantity and melts at 171°. A mixture of the low melting derivative with six to ten per cent, of the other melts at 135°. Geranial- (citral-) a. — According to Tiemann, 5 ordinary geranial consists of two geometrical isomerides termed geranial a and gera- nial b. These compounds are separated by converting geranial into the sodium bisulphite compound, decomposing it with sodium carbonate, and repeatedly agitating with ether ; a portion of the geranial is changed into the hydrosulphonic acid compound, while the remainder, about one-half of the total quantity, is dissolved by the ether. The fraction dissolved in the ether yields exclusively the semicarbazone, melting at 164°. It is called geranial a. It boils at 118° to 119° (20 mm.), has the sp. gr. 0.8898, and a 1 Wallach, Ber., 28, 1957. 2 Tiemann and Semmler, Ber., 28, 2133. 3 Barbier and Bouveault, Compt. rend., 121, 1159. ♦Tiemann, Ber., 32, 115; 31, 3324. sTiemann, Ber., 32, 115; 33, 877. GERANIC ACID. 401 refractive index, 112,= 1.4891. Its chemical properties are pre- cisely like those of ordinary geranial. Geranial- (citral-) b. — The geranial produced on decomposing the hydrosulphonic acid derivative referred to under geranial a yields large amounts of the semicarbazone, melting at 171°, together with small quantities of the lower melting compound ; it consists, there- fore, chiefly of geranial 6, and some geranial a. Geranial b is separated from the mixture by means of its compound with cyano- acetic acid (b-geranialidene cyanoacetic acid, see below) ; the latter is formed less rapidly than the corresponding a-derivative. Geranial b has the same chemical properties as geranial a ; it boils at 102° to 104° (12 mm.), sp. gr. = 0.888 and n^ = 1.49001, at 19°. Its oxime boils at 136° to 138° (11 mm.), its semicarba- zone melts at 171°, and its ß-naphthocinchonic acid melts at 200°. Geranionitrile, C 9 H 15 C]S", is obtained almost quantitatively by boiling one part of geranialoxime with two and one-half parts of acetic anhydride for half an hour ; the nitrile is separated by frac- tionally distilling the reaction-product in vacuum. It boils at 1 10° under 10 mm. pressure, has the specific gravity 0.8709 and the refractive index, n^ = 1.4759, at 20° (Tiemann and Semmler). Geranie acid, C 9 H 15 COOH, is prepared by warming geranial with moist silver oxide (Semmler 1 ). It may be more conveniently obtained by boiling geranionitrile with alcoholic potash until am- monia is no longer eliminated (Tiemann and Semmler 2 ). It is a colorless liquid, and is readily soluble in alcohol, ether, benzene, and chloroform ; its odor resembles that of the higher fatty acids. It boils at 153° (13 mm.), has the specific gravity 0.964 and index of refraction, n^ = 1.4797, at 20°. A partial synthesis 3 of this acid consists in the condensation of methyl heptenone with ethyl iodoacetate in the presence of zinc ; the product is decomposed with water, yielding a colorless oil, C 10 H 17 O 2 • OC 2 H 5 . When this compound is boiled with acetic acid and some zinc chloride, the ethyl ester of geranic acid is formed ; or, if the acid, C 10 H 17 O 2 • OH, corresponding to the com- pound, C 10 H 17 O 2 • OC 2 H 5 , is boiled with acetic anhydride, it is con- verted into geranic acid. Geranic acid is converted into citronellic acid, C 10 H lg O 2 , when it is reduced with sodium and amyl alcohol. 1 Semmler, Ber., 23, 2965; 2k, 201. 2 Tiemann and Semmler, Ber., 26, 2708; 28, 2137. »Barbier and Bouveault, Compt. rend., 122, 393; compare Tiemann, Ber., 33, 559. 26 402 THE TERPENES. Geraniolene, C 9 H 16 . — "When geranic acid is distilled at the or- dinary pressure, it decomposes into carbonic anhydride and geranio- lene ; this hydrocarbon is a liquid, boiling at 142° to 143°, has the sp. gr. 0.757 and the refractive power, n^, = 1.4368, at 20°. It forms a liquid tetrabromide, C 9 H 16 Br 4 . Geranic acid, geraniolene, and other compounds of the geranial series may be very readily converted into a mixture of two isomeric cyclic compounds by the action of dilute acids. The isomerism of these two classes of compounds is explained by the difference in position of the double linkage in the ring. They are designated as a- and /2-cyclo-compounds ; the a-cyclo-geranial derivatives may be regarded as derived from isogeronic acid or ß, /9-dimethyl adipic acid, while those of the /9-series may be referred back to geronic acid and a, a-dimethyl adipic acid. 1 a- and /3-Cyclo -geranic acids, 1 C 9 H 15 COOH. — When geranic acid is shaken with sixty-five to seventy per cent, sulphuric acid at 0° for several days, a mixture of the two cyclo-acids, together with some other products, is formed. After two or three days, a- cyclo-geranic acid separates from the reaction-product in crystals, which are filtered, pressed on a plate, and recrystallized from petroleum ether; the pure acid melts at 106°. When the liquid filtrate from the crystalline a-acid is extracted with ether, the ether evaporated, and the resulting oil repeatedly distilled under atmospheric pressure, a mixture of a- and /9-cyclo-geranic acids is obtained ; the /9-acid can not be separated from this liquid mixture in a crystalline condition, but its presence may be proved by its characteristic oxidation products. A larger yield of /3-cyclo-geranic acid is obtained if geranic acid is introduced into four parts of concentrated sulphuric acid at 0°, and the mixture is then gradually warmed to 50° and poured into water. This method, however, does not give a crystalline ß- acid,but that it is formed in considerable quantity is shown by its oxidation products. a-Cyclo-geranic acid crystallizes from water or ligroine in needles, melts at 106°, and boils at 138° (11 mm.); it may also be distilled without decomposition under atmospheric pressure. It unites directly with bromine, producing a dibromide which melts at 121°. Oxidation with potassium permanganate con- verts the a-acid into dioxydihydrocyclogeranic acid, C 9 H 15 (OH) 2 .- COOH, melting at 198° to 200°, and keto-oxydihydrocyclogeranic Niemann and Krüger, Ber., 26, 2693; Tiemann and Semmler, Ber., 26, 2725; Tiemann, Ber., 83, 3703, 3710, 3713, 3719 and 3726; Tiemann and Schmidt, Ber., 31, 881. a- AND /3-CYCLO-GERANIONITRILES. 403 add, C 10 H 16 O 4 , melting at 145° ; the latter acid yields a semi- carbazone, melting at 216°. On oxidizing either the dioxy-acid or the keto-oxy-acid with one molecular proportion of chromic acid, isogeronic acid, C 8 H 15 0-COOH, is formed ; this is an open- chain, ketonic acid, which forms a sernicarbazone, melting at 226°. When the ethyl ester of dioxydihydrocyclogeranic acid is oxi- dized with chromic acid, it yields the hydrogen ethyl ester of a- acetyl-ß, ß,-dimethyl adipio add, /COOH C 8 H u O< \COOC 2 H 5 ; this is an oil, which gives a sernicarbazone melting at 157°. When this ester is heated with an aqueous solution of potassium hydroxide, it undergoes a ketone hydrolysis and forms isoger- onic acid. # These oxidation products of cc-cyclo-geranic acid indicate that it is a ß, ^-unsaturated acid, and that it may be termed methyl-1- dimethyl-5-cyclohexene-l-methyl-acid-6. ß-Cyclo-geranic acid is formed, as above mentioned, during the inversion of the aliphatic geranic acid by means of sixty-five to one hundred per cent, sulphuric acid ; this method, however, does not give a pure product. The pure acid may be readily formed by the careful oxidation of ß-cyclo-geranial with air or with the calculated quantity of permanganate in the cold. It crystallizes from ligroine in large, transparent prisms or plates, and melts at 93° to 94° ; it distills undecomposed at atmospheric pressure. It decolorizes bromine very slowly, yielding hydrogen bromide. Its behavior towards oxidizing agents is quite different from that of the a-cyclo-acid. Oxidation with alkaline potassium perman- ganate converts /?-cyclo-geranic acid into an oxy-add, C 10 H 16 O 3 , which melts with decomposition at 186°, a ketonic acid, C 9 H 12 0 3 , which melts at 189° and yields a sernicarbazone melting at 240°, and, as chief product, a, a-dimethyl glutaric acid. a- and /3-Cyclo-geranionitriles, 1 C 9 H 15 CN. — A mixture of the two nitriles is produced by shaking geranionitrile with seventy per cent, sulphuric acid ; a separation of the two nitriles has not yet been accomplished, but their presence in the reaction-product is proved by their conversion into the a- and /9-cyclo-acids and their derivatives. The mixture of the two nitriles boils at 87° to i Tiemann and Semmler, Ber., 26, 2725; Tiemann and Schmidt, Ber., SI, 881; Tiemann, Ber., 33, 3705; compare Barbier and Bouveault, Bull. See. Chim., 15 [III.], 1002. 404 THE TERPENES. 88° (11 mm.), has the sp. gr. 0.9208 and the refractive index, n^, == 1.4734, at 20°. It forms an amidoxime, melting at 165°, whilst the corresponding compound of the aliphatic geranionitrile is a liquid. a- and /?-Cyclo-geraniolenes, C 9 H 16 , cannot be obtained by the distillation of the corresponding cyclo-geranic acids, but a mixture of the two hydrocarbons may be prepared by shaking geraniolene with ten parts of sixty-five per cent, sulphuric acid for three days ; the yield is sixty to seventy per cent. It boils at 138° to 140°' has the sp. gr. 0.7978 and refractive index, n^ = 1.4434, at 22°! Oxidation with permanganate converts this mixture of a- and /?-cyclo-geraniolenes into isogeronie acid, C 8 H 15 O.COOH, which gives a semicarbazone melting at 198° and insoluble in ethyl ace- tate, and geronic acid, C 8 H 15 O.COOH, which yields a semicar- bazone melting at 164° and readily soluble in ethyl acetate ; geronic acid 1 is an open-chain compound and is also a product of the oxi- dation of ionone with permanganate. a- and ß-Cyclo-geranials, 2 C 10 H 16 O. — While the compounds of the geranial series in general yield cyclo-derivatives on the action of acids, by the union of the carbon atoms in positions 1 and 6 geranial itself is converted into cymene. If, however, the sensitive aldehyde group in geranial be protected, as in geranialidene cyano- acetic acid, the normal cyclo-derivatives may be obtained. Thus, when either a- or b-geranialidene cyanoacetic acid is boiled for twenty hours with dilute sulphuric acid (1 part of acid to 8 parts of water), it is converted into the solid cyclo-geranialidene cyano- acetic acid (a mixture of the a- and /2-cyclo-derivatives) ; when the latter is hydrolyzed with potash, a mixture of a- and /?-cyclo- geranial is formed, of which only the /9-compound has so far been obtained in a pure condition. /9-Cyclo-geranial is a colorless oil, having the odor of carvone ; it boils at 88° to 91° (10 mm.) or 95° to 100° (15 mm.), has the sp. gr. 0.959 at 15° and 0.957 at 20°, and the refractive index, n^ = 1.49715, at 15°. Its semicarbazone crystallizes from methyl alcohol in large prisms containing methyl alcohol and melting at 165° to 166°; it separates from ethyl acetate in thin leaflets melting at 166° to 167°. By the action of acids, it is quantita- tively converted into /2-cyclo-geranial. /9-Cyclo-geranial forms an additive compound, C n H 21 0 2 N 3 , with semicarbazide, which crystallizes from a mixture of ethyl acetate and benzene in needles, and melts with decomposition at 250°. iTiemann, Ber., SI, 808. «Tiemann, Ber., 33, 3719; Schmidt, Ber., 34, 2451. GERANIALIDENE BISACETYLACETONE. 405 When /2-cyclo-geranial is condensed with acetone, ß-ionone is formed. /?-Cyclo-geranial is readily oxidized into /3-cyclo-geranic acid on exposure to the air. On oxidation with potassium permanganate, /3-cyclo-geranial yields /3-cyclo-geranic acid and oxidation products of this acid, together with geronic add, 0 9 H 16 O 3 , the methyl ketonic acid corresponding to a, oc-dimethyl adipic acid. Geranialidene cyanoacetic acid, 1 C 9 H 15 • CH = C(CN) • COOH, is formed when cyanoacetic acid is shaken with geranial in the pres- ence of aqueous sodium hydroxide ; on acidifying the reaction- mixture, the product separates as an oil which soon solidifies. The crude product melts at 85° to 90°, but after repeated crys- tallizations from benzene, it melts at 122°. It is probable that this compound consists of a mixture of the cyanoacetic acid derivatives of geranial a and geranial 6. By the action of dilute sulphuric acid it is converted into the eyclo- derivative. ^-Geranialidene cyanoacetic acid crystallizes from petroleum ether in yellowish needles, and melts at 94° to 95°. Geranialidene bisacetylacetone 2 is formed by the condensation of geranial and acetyl acetone in the presence of a few drops of piperidine ; it crystallizes from a mixture of alcohol, ether and ligroine, and melts at 46° to 48°. Labbe 3 mentions a polymeride of geranial, (C 10 H 16 O) x , which results by the action of alcoholic potash on geranial. It melts at 81° to 82°. It should be mentioned that, according to Stiehl, 4 lemongrass oil contains three isomeric aldehydes which he terms " oitriodoral- dehyde," " allolemonal " (" 1-licarhodol "), and " geranial" Sub- sequent investigations by other chemists seem to have indicated that Stiehl's three aldehydes are all identical with geranial (citral). When geranial is carefully oxidized with a chromic acid mix- ture or with a glacial acetic acid solution of chromic anhydride at a very low temperature, methyl hexylene ketone (methyl hepte- none), C 8 H u O, is formed (Tiemann and Semmler 5 ). This ketone is identical with the compound previously prepared by Wallach by the distillation of cineolic anhydride. The identity of these two » Tiemann, Ber., SI, 3324; 83, 877 and 3720; Verley, Bull. Soc. Chim., 21 [in.], 413 and 414. *K. Wedemeyer, Inaug. Diss., Heidelberg, 1897. sLabbe, Bull. Soc. Chim., 21, 407. *W. Stiehl, Journ. pr. CI em., 58, 51. s Tiemann and Semmler, Ber., 26, 2708. 406 THE TERPENES. ketones, C g H 14 0, has been determined by Tiemann and Semmler by the formation of tribromo-methyl hexylene carbinol (tribromo- heptanonol), C 8 H 12 Br 3 OOH ; this substance is produced by the action of bromine and sodium hydroxide on methyl hexylene ke- tone, and melts at 98° to 99°. The ketone, C 8 H 14 0, is likewise obtained by the oxidation of geraniol, and is also formed as a by-product during the prepara- tion of geranic acid from geranionitrile by the action of alcoholic potash. Methyl hexylene carbinol, C 8 H 15 OH, results, together with geranic acid and methyl hexylene ketone, in the hydrolysis of geranionitrile. It should be especially noted that methyl heptenone, C 8 H 14 0, occurs, together with geraniol and geranial, in many ethereal oils. Its constitution has been explained by Tiemann and Semmler's 1 investigations, according to which the ketone is almost quantitatively converted into acetone and laevulinic acid by successive oxidation with potassium permanganate and chromic acid. When geranial is carefully oxidized with chromic anhy- dride, an uncrystallizable acid, C 9 H 15 (OH) 2 COOH, is obtained which gives methyl hexylene ketone on distillation (Tiemann and Semmler). According to Barbier and Bouveault, 2 when geranial is oxidized with sodium dichromate and sulphuric acid at a low temperature, it yields formic acid, acetic acid, and a methyl hep tenon carboxy lie acid ; this acid is probably identical with the acid, C 9 H 15 (OH) 2 COOH, obtained by Tie- mann and Semmler. By more vigorous oxidation with boil- ing chromic acid mixture, geranial is converted into carbon dioxide, formic acid, acetic acid and terebic acid (Barbier and Bouveault). In this connection it should be mentioned that some of the derivatives of geranial described in the preceding were prepared by different chemists before Tiemann and Semmler obtained them, but such compounds were generally designated by different names. Thus, Barbier 3 first prepared geranialoxime, and con- verted it into geranionitrile and then into geranic acid. Geranic acid was previously described by Eckart 4 under the name " rho- dinolic acid." From the results of their experiments, Tiemann and Semmler 1 Niemann and Semmler, Ber., 28, 2126. »Barbier and Bouveault, Compt. rend., 118, 1050; 122, 393. 3 Barbier, Compt. rend., 116, 883. * Eckart, Arch. Pharm., 229, 355. Ct-IONONE. 407 regard the following formulas as expressing the true constitution of geranial and its derivatives : CH — C=CH— CH a -CH— C=CH— CHO, CH S CH 3 Geranial (citral) ( dimethyl-2, 6-octadiene-2, 6-al-8). CH 3 -C=CH-CH 2 -CH-C=CH-COOH CH 3 CH 3 Geranie acid (dimethyl-2, 6-octadiene-2, 6-acid-8). CH 3 — C=CH — CH 2 — CH S — CO — CH 3 CH 3 Methyl hexylene ketone (methyl-2-heptene-2-on-6). It should further be mentioned that geranial undergoes con- densation with acetone, yielding a ketone, pseudoionone, 1 its constitution is represented by the formula, CH 3 -C=CH-CH 3 -CH J -C=CH-CH=CH-CO-CH s . CH S CH 3 Pseudoionone, C 13 H 20 O, boils at 143° to 145° under a pressure of 12 mm., has the specific gravity 0.9044, and the refractive power, n D = 1.5275. When it is boiled with dilute sulphuric acid and ^ a little glycerol, it is converted into a mixture of two isomeric, cyclic ketones, a- and ß-ionone. This mixture was at first thought to be an individual chemical compound and was called ionone, 1 C 13 H 20 O. It boils at 126° to 128° (12 mm.), has the sp. gr. 0.9351 and the refractive index, n^ = 1.507, at 20°. a-Ionone, 2 C 13 H 20 O, is prepared from a mixture of the a- and /9-ionones (" commercial ionone ") by conversion into its oxime, crystallizing this compound from petroleum, and regenerating the ketone with dilute sulphuric acid. It boils at 123° to 124° (11 mm.) or 134° to 136° (17 mm.), has the sp. gr. 0.932 and the refractive index, n^ = 1.4980. Its oxime crystallizes from petro- leum and melts at 89° to 90°, while the oxime of /9-ionone is a liquid, hence a separation of the two ketones is rendered possible. The semicarbazone dissolves more readily than the /3-derivative in petroleum, and melts at 107° to 108°. Other characteristic de- rivatives have been prepared. iTiemann and Krüger, Ber., 26, 3691. Niemann, Ber., 81, 808 and 867; 88, 3704 and 3726; compare Lemme, Chem. Centrl., 1900 [I.], 576. 408 THE TERPEJSTES. /9-Ionone, C 13 H 20 O, is obtained from the mixture of the isomeric ketones by means of its semicarbazone, which crystallizes more readily than the corresponding a-derivative. The ketone boils at 127° to 128.5° (10 mm.) or 140° (18 mm.), has the sp. gr. 0.946 and the refractive index, n^ = 1.521. Its oxime is an oil, and its semicarbazone melts at 148° to 149°. Oxidation with permanganate converts a-ionone into isogeronie acid, C 9 H 16 0 3 , and oxidation products of the latter, while /?-ionone gives rise to geronic acid and its oxidation products. The con- stitutional formulas of the two ketones are : CH 3 CH 3 CH3CH3 X /H X H 2 C (V H 2 C 0 — CH = CH — CO — CH, I X CH = CH— CO-CH3 3 HjC C-CH, H 2 C C-CH, Q CH 2 H a-Ionone. /3-Ionone. Commercial ionone has the characteristic odor of violets, and for this reason it is of considerable practical importance. 1 Irone, 1 C 13 H 20 O, is a structural isomeride of ionone, and is the fragrant constituent of violets. It is an oil which is readily solu- ble in alcohol, boils at 144° (16 mm.), has the sp. gr. 0.939 and refractive index, n D = 1.50113, at 20° ; it is dextrorotatory. Since it is impracticable to introduce into this book the results of many investigations on geranial, reference may be made to the following publications : Bouveault, Bull. Soc. Chim., 21 [III.], 419 and 423. Barbier, Bull. Soc. Chim., 21 [III.], 635. Corie, C. and D., 5£, 650. Doebner, Ber., 31, 3195. Flatau, Bull. Soc. Chim., 21 [III.], 158. Flatau and Labbe, Bull. Soc. Chim., 19 [III.], 1012. Ipatieff, Ber., Sj., 594. Labbe, Bull. Soc. Chim., 21 [III.], 77, 407 and 1026. Semmler, Ber., 31, 3001. Stiehl, Jo urn. pr. Chem., 58, 51. iTiemann and Krüger, Ber., 26, 2675; 28, 1754; Barbier and Bouveault, Bull. Soc. Chim., 15 [III.], 1002; Tiemann, Ber., 31, 808, 867, 1736, 2313, and 3324; 32, 115; 33, 877, 3704 and 3726; Ziegler, Journ. pr. Chem., 57 [II.], 493. * CITKONELLAL. 409 Tiemann, Ber., 31, 2313, 3278, 3297 and 3324; 32, 107, 250, 812, 827 and 830. Verley, Bull. Soc. Chim., 21 [III.], 408, 413 and 414. Ziegler, Journ. pr. Chem., 57 [II.], 493. 2. MENTHOCITRONELLAL, C 10 H 18 O. This aldehyde, 1 previously termed menthonyl aldehyde, results on the oxidation of menthocitronellol (menthonyl alcohol) with chromic acid. It has an odor like that of sweet orange, boils at 86° to 88° (16 mm.), and at about 200° under atmospheric pressure ; it has the specific gravity 0.8455 and the refractive index, n D = 1.43903, at 20°. Menthocitronellal-/?-naphthoeinchonic acid is formed by the con- densation of the aldehyde with /?-naphthylamine and pyroracemic acid; it melts at 214° to 215° (the corresponding derivative of natural citronellal melts at 225°). Menthocitronellal semicarbazone melts at 89°, and is optically inactive. 3. CITRONELLAL, C 10 H 18 O. This compound was formerly called " eitronellone " ; it has, how- ever, been characterized as an aldehyde, and, in order to indicate the aldehydic nature, is now termed citronellal. It derives its name from its occurrence in oil of citronella (from Andropogon nardus) ; this oil has been carefully studied by Gladstone, 2 Wright, 3 Kremers, 4 and Dodge. 5 It has been found by Schimmel & Co. in the oils of Eucalyptus maculata and Eucalyptus maculata var. citriodora, and, according to Döbner, it also accompanies geranial in the oil of lemon. In order to prepare citronellal from citronella oil or eucalyptus oil, the ethereal oil is shaken with a solution of acid sodium sul- phite, and the resulting crystalline, additive compound is decom- posed with sodium carbonate ; pure citronellic aldehyde is then obtained by distilling the reaction-product in a current of steam. The citronellal so obtained from the ethereal oils is dextrorotatory ; it is possible, however, that the specimens of citronellal having low rotatory powers will prove to be mixtures of the two optically active modifications. i Wallach, Ann. Chem., 278, 313; 296, 120. 2 Gladstone, Journ. Chem. Soc, 1872, 7. a Wright, Journ. Chem. Soc, 1875, 1. *Kremers, Proc. Amer. Pharm. Assoc., 1887; Amer. Chem. Journ., 14, 203 ; Ber., 25, 644, Ref. »Dodge, Amer. Chem. Journ., 11, 456; 12, 553; Ber., 28, 175, Ref.; 2*, 90, Ref. 410 THE TERPENES. Citronellal may also be prepared by the oxidation of citron ellol with chromic acid ; the yield, however, is small. By means of this method a levo-citronellal may be obtained from the 1-citronellol of rose oil. Citronellal is a colorless liquid, boils at 205° to 208° at ordi- nary pressure, and at 103° to 105° under a pressure of 15 mm.; the specific gravity is 0.8538 at 17.5°, and the refractive index, np = 1.4481. Its optical rotation was found by Kremers to be [a]j) = -f 8.18°, and by Tiemann and Schmidt, 1 -f 12°30'. Pure citronellal is very unstable ; when allowed to stand for several months, it is almost entirely converted into isopulegol ; 2 the same isomeric change is effected much more rapidly by the action of acids. 3 When citronellal is treated with alkalis, it is completely resinified. When it is reduced in alcoholic solution with glacial acetic acid and sodium amalgam, it yields citronellol, C 10 H 19 OH (Dodge, Tiemann and Schmidt). On oxidizing citronellal with silver oxide, citronellic acid, C 10 H 18 O 2 , is obtained (Semmler). Oxidation with potassium per- manganate, followed by chromic and sulphuric acids, converts citronellal, like citronellol and citronellic acid, into acetone and /3-methyl adipic acid. The aldehyde is, therefore, to be regarded as dimethyl-2, 6-octene-2-al-8 (Tiemann and Schmidt): CH,— C=CH— CHj— CH a — CH— CH 2 — CHO. CH 3 CH 3 It unites with two atoms of bromine, forming a liquid additive product (Dodge, Semmler). According to Barbier, 4 menthoglycol, C 10 H 18 (OH) 2 , is formed by agitating citronellal with dilute sulphuric acid. The normal addition-product of citronellal and sodium bisul- phite, 5 C 10 H 18 O-NaHSO 3 , is a crystalline compound, and is formed by shaking a cold solution of sodium bisulphite (free from sul- phurous anhydride) with citronellal ; it is soluble in water, but may be precipitated by the addition of a saturated salt solution. Sodium carbonate or hydroxide converts it into citronellal. A mono- and dihydrosulphonio acid are also described. 5 'Tiemann and Schmidt, Ber., 29, 905. 2 Labb6, Bull. Soc. Chim., 21 [III.], 1023; compare Tiemann, Ber., 32, 825. »Tiemann and Schmidt, Ber., 29, 913 ; 80, 22. 4 Barbier and Leser, Compt. rend., 124, 1308. 5 Tiemann, Ber., 31, 3297. CITRONELL A L-/3-N APHTHOCI NCHONIC ACID. 411 Citronellylidene cyanoacetic acid, 1 C n H 18 (CN)COOH, is formed by shaking citronellal with an aqueous solution of cyanoacetic acid and sodium hydroxide ; it crystallizes from benzene or alcohol, and melts at 137° to 138°. Its sodium salt is sparingly soluble, and is especially characteristic. Citronellal dimethylacetal, 2 C 10 H 18 (OCH 3 ) 2 , is obtained by treat- ing citronellal with a one per cent, solution of hydrogen chloride in methyl alcohol. It boils at 110° to 112° (12 to 13 mm.), and has the specific gravity 0.885 at 11.5°. Phosphoric anhydride converts citronellal into a mixture of a terpene (b. p. 175° to 178°), and citronellal phosphoric acid; the latter crystallizes from water in prisms, melting at 203°. It is a monobasic acid, forms crystalline salts, and has the formula (Dodge) : was discovered by Döbner. It is especially valuable for the characterization of this alde- hyde, and is prepared by heating an alcoholic solution of an excess of citronellal with the molecular proportions of pyroracemic acid and /?-naphthylamine, for three hours. On cooling, citronellal-/?- naphthocinchonic acid separates in crystals ; these are washed with ether, and recrystallized from alcohol containing hydrochloric acid. The resultant hydrochloride is dissolved in ammonium hydroxide, and the pure acid is precipitated from the ammoniacal liquid by acetic acid ; it is again crystallized from dilute alcohol, and forms colorless needles, melting at 225°. When heated above its melting point, this compound loses car- bonic anhydride and yields citron ellal-/9-naph thy 1 quinoline ; this amine crystallizes from dilute alcohol or petroleum ether in bright needles, which melt at 53°. C 9 H n CH^CAP=0. H— 0/ Citronellal-/9-naphthocinchonic acid, COOH iTiemann, Ber., 32, 824. a Harries, Ber., 38, 857; 34, 1498 and 2981. 412 THE TERPEJSTES. Citronellaloxime, 1 C 10 H lg NOH, was obtained by Kremers, and subsequently by Semmler, 1 by the action of hydroxylamine on an alcoholic solution of citronellal. It is an oil, which boils at 135° to 136° (14 mm.), has a specific gravity of 0.9055 and refractive index, n^ = 1.4763, at 20°. Citronellonitrile, 1 C 9 H 17 CN, results on boiling the oxime with acetic anhydride. It boils at 94° under 14 mm. pressure, has the specific gravity 0.8645 and the index of refraction, n^ = 1.4545, at 20°; the molecular refraction is 47.43. Citronellic acid, C 9 H 17 COOH, was prepared by Dodge, 2 Semm- ler, 3 and Kremers 4 by the oxidation of citronellal with moist silver oxide. It is more readily formed by the saponification of the corresponding nitrile with alcoholic potash (Semmler 5 ). It boils at 143.5° (10 mm.) and at 257° under atmospheric pres- sure ; its specific gravity is 0.9308 and the refractive power, np = 1.4545, at 20°. The molecule of citronellic acid appears to contain one double linkage. Citronellic acid is further obtained from geranic acid, C 9 H 15 COOH, by reduction with sodium and amyl alcohol. 6 A small amount of citronellal is formed by strongly heating a mixture of calcium citronellate and formate. 6 ^ Citronellamide, 6 C 9 H 17 CONII 2 ,is produced by boiling citronello- nitrile with a fifteen per cent, alcoholic potash solution during five or six hours. It crystallizes from petroleum ether in colorless needles, melts at 81.5° to 82.5°, is sparingly soluble in water, but dissolves readily in most organic solvents. _ Dioxycitronellic acid, C 9 H 17 (OH) 2 COOH, is formed by oxidizing citronellic acid with a very dilute solution of permanganate at 0°. It is a viscous liquid, and appears not to yield a lactone. On further oxidation with a chromic acid mixture, it yields /9-methyl adipic acid, C 7 H 12 0 4 (Semmler's citronellapimelic'acid). Citronellal semicarbazone, 7 C 10 H 18 = N • NHCONH 2 , is obtained by shaking an alcoholic solution of citronellal with a solution of semicarbazide hydrochloride and sodium acetate ; it crystallizes from chloroform and ligroine in white leaflets, and melts at 84°. Temmler, Ber., 26, 2254; compare Tiemann and Krüger, Ber., 29, 926; Tiemann and Schmidt, Ber., SO, 33. 2 Dodge, Amer. Chem. Journ., 11, 456; 12, 553. 3 Semmler, Ber., 24, 208. «Kremers, Amer. Chem. Journ., 1^, 203. 5 Semmler, Ber., 26, 2254; compare Tiemann and Schmidt, Ber., SO, 33; Barbier and Bouveault, Compt. rend., 122, 673, 737, 795 and 842. sTiemann, Ber., SI, 2899. 'Tiemann and Schmidt, Ber., SO, 34; SI, 3307; compare Barbier and Bouveault, Compt. rend., 122, 737. OXYHYDROMENTHONYLAMINE. 413 C. AMINES. 1. MENTHONYLAMINE, C 10 H 19 NH 2 . According to Wallach, 1 menthonylamine, C 10 H 19 NH 2 , is formed, together with oxyhydromenthonylamine, C 10 H 20 (OH)NH 2 , by the reduction of menthonitrile with sodium and alcohol. Thirty grams of sodium are gradually added to the solution of fifty grams of the nitrile in two hundred and fifty grams of abso- lute alcohol ; when the reaction is complete, the product is dis- tilled in a current of steam, the distillate is treated with a solution of thirty-five grams of oxalic acid, and the non-basic impurities are removed from the oxalic acid solution by redistillation with steam. On cooling, the sparingly soluble menthonylamine oxalate crystallizes in leaflets, whilst the oxalate of the base, C^H^NO, remains in solution. Menthonylamine, obtained from its oxalate, boils without decom- position at 207° to 208°; it resembles the isomeric menthylamine in readily absorbing carbonic anhydride from the air. It has the specific gravity 0.8075 at 20° (the sp. gr. of menthylamine is 0.8600), and the index of refraction, n^, = 1.4500. It is feebly dextrorotatory. Menthonylamine hydrochloride, C 10 H 19 NH 2 -HC1, is a crystalline salt, stable in the air, and forms a sparingly soluble platinochloride. The acid oxalate is slightly soluble in water, and separates from it with one-half molecule of water of crystallization. Acetyl menthonylamine is a liquid. The oxamide, is very soluble in alcohol, and melts at 82° to 83°.' Menthocitronellol (menthonyl alcohol) and a hydrocarbon, C 10 H 18 , are produced on treating menthonylamine oxalate with sodium nitrite. Oxyhydromenthonylamine, C 10 H 20 (OH)NH 2 , boils at 252° to 255°, and forms very soluble salts. On treatment with nitrous acid, this amine yields dimethyloctylene glycol (2, 6-dimethyloc- tane-2, 8-diol), C 10 H 20 (OH) 2 '; it is non-volatile with steam, and boils at 153° to 156° under 19 mm. pressure. i Wallach, Ann. Chem., 278, 313; 296, 120. SESQUITERPENES AND POLYTERPENES. SESQUITERPENES, C 15 H 24 , AND SESQUITERPENE ALCOHOLS, C 15 H 25 OH. 1. OADINENE, C 15 H 24 . Cadinene resembles limonene in its behavior and in its distribu- tion in ethereal oils. Like limonene it yields solid additive prod- ucts with two molecules of halogen hydrides, but these compounds are optically active, and, by elimination of the hydrogen chloride, etc., may be reverted into optically active cadinene. Although cadinene has been recognized in many ethereal oils, it is, nevertheless, doubtful whether this hydrocarbon is actually the most widely distributed of the sesquiterpenes, since reactions by which cadinene can be definitely identified are, as a rule, unknown for the other sesquiterpenes. The name cadinene was introduced by Wallach 1 owing to the oc- currence of this sesquiterpene in large quantities in the oil of cade (Oleum eadinum). This oil is the most convenient and cheap- est source for its preparation. The investigations of Wallach, 2 Schmidt, 3 Oglialoro, 4 Soubeiran and Capitaine 5 have shown that cadinene occurs in the oil of cubeb. Wallach 2 also proved that it occurs in patchouly oil, galbanum oil and oil of savin ; Wallach and Rheindorf 6 subsequently discovered it in the oil of paracoto bark, and Wallach and Walker 7 detected it as a constituent of oil of olibanum. Bertram and Gildemeister 8 found cadinene in the oil of betel leaves and in camphor oil ; Bertram and Walbaum 9 recognized it in pine needle oil from Picea excelsa and Pinus montana, and in the German oil of Pinus silvestris. Schimmel = - 47 ° 54' (Rousset 2 ). Cedrene unites with bromine and the halogen hydrides, forming very unstable, liquid addition-products. On oxidation with an excess of chromic acid in a sulphuric acid solution, cedrene yields an acid, C 12 H lg 0 3 , which boils at 220° to 230° (9 mm.). Cedrene is not converted into an alcohol, C 15 H 25 OH, on treat- ment with glacial acetic and sulphuric acids. The solid compound, C 15 H 25 OH, occurring with cedrene in cedar wood oil, is termed cedrol or " cedar camphor." It forms a lus- trous, crystalline mass, melts at 74° and boils at 282° (Walter 3 ). It crystallizes from dilute methyl alcohol in colorless needles, and, after repeated crystallizations, it softens at about 78°, and melts at 85° to 86°. 4 It is optically active. i Wallach, Ann. Chem., 271, 299. ^Rousset, Bull. Soc. China., 17 [III.], 485. 3 Walter, Ann. Chem., 89, 247; 48, 35. * Schimmel & Co., Semi- Annual Report, Oct., 1897, 14; compare Rousset, Bull. Soc. Chim., 17 [III.], 485; Chapman and Burgess, Chem. News, 74, 95. 424 THE TERPENES. Walter observed that, when " cedar camphor " is heated with phosphoric anhydride, it is decomposed into water and a sesqui- terpene, C 15 H 24 , which he called cedrene. Rousset reports that cedrol is dehydrated with formation of a sesquiterpene by the action of benzoyl chloride, and by chromic acid, and partially by acetic anhydride ; however, on heating with the latter reagent at 100°, a part of the cedrol is converted into an acetate, Q H O - COCH3, which boils at 157° to 160° (8 mm.). According to Schimmel & Co., water is very readily eliminated from cedrol by the action of concentrated formic acid at the ordi- nary temperature ; the hydrocarbon, C 15 H 24 , thus obtained boils at 262° to 263°, and is levorotatory, [0]^== —80°. It appears to be identical with the cedrene occurring in cedar wood oil. Cedrol reacts like a tertiary alcohol since it does not give rise to an aldehyde or ketone on oxidation. Cedrone, C 15 H 24 0, is a ketone which is formed on the oxidation of natural cedrene with an acetic acid solution of chromic anhy- dride ; it boils at 147° to 151° (7.5 mm.), does not form a crys- talline derivative with sodium bisulphite, but yields iodoform on treatment with sodium hypobromite and potassium iodide. Its oxime boils at 175° to 180° (8 mm.), and is converted into an acetate (b. p. 185° to 190° at 9 mm.) by acetic anhydride. Isocedrol, C 15 H 25 OH, results on reducing cedrone in an ethereal solution with sodium. This alcohol, isomeric with " cedar cam- phor," boils at 148° to 151° (7 mm.), and yields a benzoate, boil- ing at 221* to 223° under 6 mm. pressure. 6. CUBEB CAMPHOR, C 15 H 25 OH. The oil of cubeb, prepared from oldcubebs, contains the sesquiter- pene cadinene, and a sesquiterpene alcohol, C 15 H 25 OH ; this alcohol has been the subject of investigations by Blanchet and Sell, 1 Wink- ler, 2 Schaer and Wyss, 3 and Schmidt. 4 Cubeb camphor separates from a mixture of ether and alcohol in large, odorless, rhombic crys- tals, melts at 65°, and boils at 248° with the elimination of a small quantity of water. It is optically levorotatory. It loses water when it is heated at 200° to 250° or allowed to remain in a desic- cator over sulphuric acid ; the nature of the resultant sesquiter- pene, cubebene has not been explained. •Blanchet and Sell, Ann. Chem., 6, 294. »Winkler, Ann. Chem., 8, 203. 3 Schaer and Wyss, Jahresb. Chem., 1875, 497. «Schmidt, Zeitschr. für Chem., 1870, 190; Ber., 10, 189. PATCHOULY ALCOHOL AND PATCHOULENE. 425 7. LEDUM CAMPHOR, C 15 H 25 OH, AND LEDENE, C 15 H 24 . Ledum camphor 1 occurs in the oil of Labrador tea, obtained from the leaves of Ledum palustre. When purified by recrys- tallization from alcohol, it melts at 104° to 105°, and boils at 282° to 283°. It sublimes in long, white needles, and its solution in alcohol is feebly dextrorotatory, [«] y = -f 7.98°. It is a powerful poison, affecting the central nervous system. Ledum camphor readily loses water by warming with acetic anhydride or dilute sulphuric acid and yields ledene, C 15 H 24 , which is an oil boiling at 255°. The chloride, C 15 H 25 C1, is obtained as a yellowish oil by the careful action of phosphorus pentachloride on a solution of the camphor in petroleum ether. Ledum camphor must be considered as a tertiary sesquiterpene alcohol, since it is not attacked by potassium permanganate (Hjelt 2 ). 8. PATCHOULY ALCOHOL, C 15 H 25 OH, AND PATCHOULENE, The oil of patchouly contains liquid substances, together with a solid compound which was investigated by Gal, 3 and Montgolfier, 4 and named "patchouly camphor." More recently, Wallach and Tuttle 5 recognized the alcoholic nature of this compound and called it patchouly alcohol. It forms hexagonal prisms, melting at 56°, boils at 206°, and is optically levorotatory. It has long been known that patchouly alcohol can be decom- posed by the action of acetic anhydride into water and a sesqui- terpene, C 15 H 24 . According to Wallach and Tuttle, the same hydrocarbon, patchoulene, is obtained by the action of feeble de- hydrating agents on the alcohol. The best method for preparing this sesquiterpene is by heating patchouly alcohol with acid potassium sulphate at 180°, for one and one-half hours. Patchoulene boils at 254° to 256°, has the specific gravity of 0.939 at 23°, and the index of refraction, n^ = 1.50094. It has an odor recalling that of cedrene, and apparently contains one ethylene linkage. ^izza, Journ. Russ. Chem. Soc, 19, 319; Iwanow, Jahresb. Chem., 1879, 909; Trapp, Ber., 8, 542; Hjelt and Collan, Ber., 15, 2501; Hjelt, Ber., 28, 3087. 2 Hjelt, Ber., 28, 3087. »Gal, Zeitschr. für Chem., 1869, 220. *Montgolfier, Bull. Soc. Chim., 28, 414. «Wallach and Tuttle, Ann. Chem., 279, 394. 426 THE TEEPENES. 9. GUAIOL, C 15 H 25 OH. The sesquiterpene alcohol obtained by Schimmel & Co. 1 from the oil of guaiac wood is identical with a product subsequently obtained from the so-called Champaca wood oil by distillation with steam. This compound, which is called guaiol or champacol according to its source, has been investigated by Wallach and Tuttle. 2 Guaiol is purified by distillation in vacuum, and then washing with ether. It boils at 155° to 165° under a pressure of 13 mm. When recrystallized several times from alcohol, it forms lustrous, transparent prisms, which melt at 91°, boil at 288°, and are levorotatory. The brilliant colors which are formed by the action of dehy- drating agents on guaiol are especially characteristic. When heated with zinc chloride at 180° and then distilled with steam, a blue oil is obtained. This is a sesquiterpene, and boils at 124° to 132° under 13 mm. pressure ; its specific gravity at 20° is 0.910 and the refractive index, n B = 1.50114. The blue color of this hydrocarbon is due to impurities consisting of oxidation products of* the sesquiterpene (Wallach and Tuttle). According to Schimmel & Co., acetic anhydride reacts with guaiol forming a liquid acetate, which boils at 155° under a pres- sure of 10 mm. 10. SANTALOL, C 15 H 25 OH, AND SANTALENE, C 15 H 24 . East Indian sandalwood oil consists chiefly of a mixture of two sesquiterpene alcohols, C 15 H 25 OH, which are called a- and /?-san- talol ; the two isomeric santalenes also occur in the oil, together with other compounds. A mixture of the two alcohols is fre- quently called " mntalol," and is known commercially as " gonorol." a-Santalol, 3 C 15 H 25 OH, is a colorless, oily liquid, having a faint odor; it boils at 300° to 301°, has the sp. gr. 0.9854 at 0°, and the specific rotatory power, [0]^= — 1.2°. Its acetate boils at 308° to 310°. /9-Santalol, C 15 H 25 OH, resembles its isomeride, boils at 309° to 310°, has the sp. gr. 0.9868 at 0°, and [a] i) =- 56°. Its acetate boils at 316° to 317°. These alcohols are probably primary alcohols, and, when treated 1 Schimmel & Co., Semi-Aimual Report, April, 1892, 42; April, 1893, 33. 2 Wallach and Tuttle, Ann. Chem., 279, 394. sGuerbet, Compt. rend., ISO, 417 and 1324; Soden and Müller, Pharm. Zeit., U, 258; compare Parry, C. and D., 53, 708; 55, 1023; Schimmel & Co., Semi- Annual Report, April, 1899, 38 and 40; April, 1900, 42 and 43. SANTALIC ACID. 427 with dehydrating agents, are converted into two isomeric sesqui- terpenes, a- and ß-isosantalene, C 15 H 24 . These compounds are colorless liquids, having an odor of turpentine ; the a-isosantalene boils at 255° to 256°, and has [a\ D = + 0.2°, while the /3-deriv- ative boils at 259° to 260°, and has [a]^ = + 6.1°. a-Santalene, C 15 H 24 , boils at 252° to 252.5°, has the sp.gr. 0.9134 at 0°, and [a] J) = — 13.98°. When heated in a closed tube with glacial acetic acid at 180° to 190°, it forms an acetate, C 15 H 24 • C 2 H 4 0 2 , boiling at 164° to 165° (14 mm.). When dis- solved in ether and treated with dry hydrogen chloride, it forms a dihydrochloride, C 15 H 24 • 2HC1, which decomposes on distillation in vacuum; its specific rotatory power is [a] D -= + 6°. a-Santalene forms a nitrosochloride, C 15 H 24 ■ NOC1, which crys- tallizes from benzene in prisms, and melts and decomposes at 122° ; the nitrolpiperidide crystallizes from alcohol in needles, and melts at 108° to 109°. /9-Santalene, C^H^, boils at 261° to 262°, has the sp. gr. 0.9139 at 0°, and the rotatory power, [a] D = — 28.55°. Its acetate, C 15 H 24 • C 2 H 4 0 2 , boils at 167° to 168° (14 mm.); its dihy- drochloride, C 15 H 24 • 2HC1, is decomposed on distillation, and has the rotatory power [«]# = + 8°. /?-Santalene yields a mixture of two nitrosochlorides, C 15 H 24 • - NOC1, on heating its solution in petroleum ether with nitrosyl chloride; they are separated by fractional crystallization from alcohol. The less soluble derivative melts at 152°, and the other, which is formed in larger quantities, melts at 106° ; the cor- responding nitrolpiperidides melt at 101°, and 104° to 105°, respectively. According to Soden and Müller, when santalene (/?-santalene) is treated with glacial acetic and sulphuric acids by Bertram's method, it yields a sesquiterpene alcohol, C 15 H 25 OH, which has a strong odor of cedar; it boils at 160° to 165° (6 mm.), and has the sp. gr. 0.9780 at 15°. In addition to the santalols and santalenes, East Indian sandal- wood oil contains the following compounds (Guerbet 1 ). Santalal, C I5 H 24 0. — This substance has the properties of an aldehyde, and boils at 180° (14 mm.); it is a colorless, oily liquid, having a strong odor of peppermint. It yields a semicar- bazone, which crystallizes in small needles, and melts at 212°. Santalic acid, C 15 H 24 0 2 , is a liquid, boiling at 210° to 212° under 20 mm. pressure. 1 Guerbet, Compt. rend., ISO, 417; compare Chapoteant, Bull. Soc. Chim., 37 [II.], 303; Chapman and Burgess, Proc. Chem. Soc, 1896, 140; Chap- man, Journ. Chem. Soc, 79, 134. 428 THE TERPENES. Teresantalic acid, C 10 H u O 2 , crystallizes from alcohol in prisms, melting at 157°. When West Indian sandalwood oil is saponified with alcoholic potash, and fractionally distilled in a vacuum, a sesquiterpene alco- hol, amyrol, C 15 H 25 OH, is obtained. It is a colorless, viscous liquid, having a faint odor and bitter taste; it boils at 299° to 301° (748 mm.) and at 151° to 152° (11 mm.). Its sp. gr. is 0.981 at 15°, and [a] i) = +27°. When heated with phthalic anhy- dride at 110°, it loses water and yields a sesquiterpene. 1 It is possible that amyrol, like santalol, may consist of two similar alcohols, having different rotatory powers. In a more recent publication, Soden 2 states that a-santalol is probably a sesquiterpene alcohol having the formula, C 15 H 23 OH, and not C 15 H 25 OH ; it forms the chief constituent of " santalol " and East Indian sandalwood oil. /9-Santalol may also have the formula C 15 H 23 OH. 11. GALIPOL, C 15 H 25 OH, AND GALIPENE, C 15 H 24 . According to investigations by Beckurts and Troeger, 3 the oil of angostura bark contains about fourteen per cent, of a sesqui- terpene alcohol, C 15 H 25 OH, called galipol. It boils at 264° to 265°, has the specific gravity 0.9270 at 20°, and is optically in- active ; its refractive index is n^ = 1.50624. The sesquiterpene, C 15 H 21 , galipene, is also contained in angos- tura bark oil ; it is further obtained by treating galipol with phos- phoric anhydride. It boils at 255° to 260°, has the specific grav- ity 0.912 at 19°, and is optically inactive. It yields a liquid, unstable additive product with hydrogen bromide. 12. C AP ARB APIOL , C 16 H 25 OH, AND CAPARRAPENE, C 16 H 24 . The acid-free oil obtained from the essential oil of caparrapi con- tains a sesquiterpene alcohol, caparrapiol, 4 which boils at 260° (757 mm.); it has the specific gravity 0.9146, the refractive index, np = 1.4843, and the rotatory power, [a] D = — 18.58°. When distilled with phosphoric or acetic anhydride, it is converted into the sesquiterpene, caparrapene. This sesquiterpene is a colorless liquid, which boils at 240° to 250°, has the sp. gr. 0.9019 at 16°, i Soden, Pharm. Zeit., 45, 229 and 878 ; compare Parry, C. and D., 58, 708. «Soden, Arch. Pharm., 288, 353; compare Müller, Arch. Pharm., 238, 366 ; Schimmel & Co., Semi-Annual Report, April, 1900, 43. "Beckurts and Troeger, Arch. Pharm., 235, 518 and 634; 236, 392; com- pare Beckurts and Nehring, Arch. Pharm., 229, 612; Herzog, Arch. Pharm., 143, 146. *Tapia, Bull. Soc. Chim., 19 [III.], 638. ZINGIBERENE NITEOSITE. 429 the refractive index, = 1.4953, and a rotatory power, [a]^ = — 2.21°. Its glacial acetic acid solution gives a rose coloration, changing to deep violet, on the addition of a few drops of sulphuric acid. The commercial "white oil" of caparrapi oil also contains a monobasic acid, C 15 H 26 0 3 , which crystallizes in white needles, melts at 84.5°, and has the specific rotatory power, \a~\ D = + 3°. It is sparingly soluble in cold water, soluble in hot water, and readily soluble in alcohol. Its calcium salt, Ca(C 15 H 25 0 3 ) 2 -f- 5H 2 0, crys- tallizes in needles, melting at 250° ; the silver, sodium, and am- monium salts are crystalline. 13. ZINGIBERENE, C 15 H 24 . The sesquiterpene, C 15 H 24 , which is the chief constituent of the oil of ginger, has been studied by Soden 1 and by Schreiner and Kremers. 2 It is obtained by the repeated fractional distillation of ginger oil under reduced pressure, and is a colorless and almost odorless oil ; it boils at 134° (14 mm.), 160° to 161° (32 mm.) and at 269° to 270° under atmospheric pressure. It has the sp. gr. 0.-872 at 15° or 0.8731 at 20°, the refractive index, n^ = 1.49399, at 20°, and the specific rotatory power, \ol] d = — 69° to — 73.38° (100 mm. tube). Zingiberene dihydrochloride, 2 C 15 H 24 -2HC1, is obtained by satur- ating a solution of zingiberene in an equal volume of glacial acetic acid, cooled to 0°, with dry hydrochloric acid gas, and allowing to stand during one or two days ; it crystallizes from hot alcohol in fine, white needles, which melt at 168° to 169°. Zingiberene nitrosochloride, 3 C 15 H 24 *NOCl, is formed when a mixture of zingiberene, glacial acetic acid and ethyl nitrite is cooled in a freezing mixture and is treated gradually with a satur- ated solution of hydrogen chloride in glacial acetic acid ; the nitrosochloride is precipitated by shaking the reaction-product with alcohol and is purified by dissolving in ethyl acetate and reprecipitating with alcohol. It forms a white powder and melts with decomposition at 96° to 97°. Zingiberene nitrosite, 3 C 15 H 24 -N 2 0 3 , results when the sesquiter- pene is dissolved in ten times its volume of petroleum ether, the solution well cooled and treated with a solution of sodium nitrite and glacial acetic acid. It crystallizes from hot methyl alcohol in fine needles and melts at 97° to 98°. »H. von Soden and Rojahn, Pharm. Zeit., 45, 414. s Schreiner and Kremers, Pharm. Arch., 4, 141 and 161. 'Schreiner and Kremers, Pharm. Arch., 4, 161- 430 THE TERPENES. Zingiberene nitrosate, C 15 H 24 *N 2 0 4 , is prepared by dissolving zingiberene in an equal volume of glacial acetic acid and ethyl nitrite, cooling in a freezing mixture, and carefully treating with a mixture of nitric and glacial acetic acids ; the product is pre- cipitated by shaking with cold alcohol. The nitrosate is purified by dissolving in acetic ether and precipitating with alcohol ; it forms a yellow powder, which melts and decomposes at 86° to 88°. Zingiberene unites with bromine, forming a liquid tetrabromide (Soden). 14. OLEFINIO SESQUITERPENE, C 15 H 24 , FROM THE OIL OF CITRONELLA. According to Schimmel & Co., 1 citronella oil contains a "light sesquiterpene" which appears to bear the same relation to the sesquiterpenes proper, as do the olefinic terpenes to the cyclic terpenes. This sesquiterpene boils at 157° (15 mm.), has the sp. gr. 0.8643 and index of refraction, n^ = 1.51849, at 15° ; it is dex- trorotatory, \_ol\d — + 1° 28'. Under ordinary pressure, it boils with decomposition at 270° to 280°. It is readily decomposed by the action of the halogens or halo- gen hydrides. It has an odor similar to that of cedar wood, and is oxidized by dilute permanganate solutions, yielding carbon dioxide, oxalic acid and a glycol. It is acted upon by a mixture of glacial acetic and sulphuric acids, forming a product having a saponification-number of 43.6. During the year 1901, Kremers 2 suggested a classification of the sesquiterpenes according to which these hydrocarbons, C^H^, may be separated into five groups as follows. Group I. Sesquiterpenes having an open-chain of carbon atoms and containing four double linkages. An example of this class is possibly to be found in the " light sesquiterpene " obtained by Schimmel & Co. from citronella oil. Group II. Monocyclic sesquiterpenes having three double link- ages. This group probably includes zingiberene and the sesqui- terpene obtained by Semmler from the oil of Carlina acaulis. Group III. Dicyclic sesquiterpenes having two double linkages. This class embraces most of the sesquiterpenes, including cadinene, caryophyllene and probably humulene. 1 Schimmel & Co., Semi-Annual Report, Oct., 1899, 23. 2 Schreiner and Kremers, Pharm. Arch., 4, 141. METATEREBENTENE. 431 Group IV. Tricyclic sesquiterpenes having one double linkage. Clovene belongs to this group. Group V. Tetracyclic sesquiterpenes without a double linkage. Eepresentatives of this class are not at present known. A further division of Group II. may be made according to whether the ring contains three, four, five or six carbon atoms. Groups III., IV. and V. may likewise be subdivided according to the number of carbon atoms contained in the ring. Many sesquiterpenes are known which have not been mentioned in the preceding pages ; but they probably consist, in part at least, of mixtures of the above described hydrocarbons, although they may also contain chemical individuals which have not yet been characterized as such. Such sesquiterpenes are found in the prod- ucts of the distillation of caoutchouc/ and in the polymerization- products of valerylene, 2 C 5 H g . Many ethereal oils also contain sesquiterpenes of an unknown nature. DITERPENES, C 20 H 32 . Very many diterpenes are known, but they have never been thoroughly characterized. Hence, only a brief enumeration of a few of these compounds which have been investigated will be given in the following. Colophene is formed by the action of concentrated sulphuric acid 3 or phosphoric anhydride 4 on oil of turpentine, and also by heating turpentine oil with benzoic acid, 5 and by the distillation of colophonium. 6 It is an oily, viscid liquid, 4 boils at 318 p to 320°, and unites with hydrogen chloride, producing a very un- stable compound. Metaterebentene 7 is produced by heating turpentine oil at 300°. It is an oily, viscous liquid, is optically levorotatory, and boils above 360° ; it has a specific gravity of 0.913 at 20°, and absorbs hydrogen chloride. Meta-australene is prepared from dextro- pinene in the same manner that metaterebentene is obtained from levo-pinene. iBouchardat, Bull. Soc. Chim., 24, 108; compare Himly, Ann. Chem., 27, 40; Williams, Jahresb. Chem., 1860, 495. 2Bouchardat, Bull. Soc. Chim., S3, 24; Reboul, Ann. Chem., US, 373. sDeville, Ann. Chem., 37, 192. «Deville, Ann. Chem., 71, 350. sBouchardat and Lafont, Compt. rend., 113, 551; Ber., 1891, 904, Kef. sRiban, Ann. Chim. Phys. [5], 6, 40; Armstrong and Tilden, Ber., 1879, 1755. 'Berthelot, Ann. Chim. Phys. [3], 39, 119. 432 THE TERPENES. Dicinene 1 is obtained by the action of phosphoric anhydride on wormseed oil ; it boils at 328° to 333°. Diterpilene 2 is formed when oil of turpentine is heated with crystalline formic acid for twelve hours, or when limonene is allowed to remain in contact with formic acid at the ordinary temperature for some time. It is a thick oil, is optically inactive, and has an odor like that of balsam of copaiba; it boils at 212° to 215° under 40 mm. pressure, and has the sp. gr. 0.9404 at 0°. It readily changes into a resinous mass on exposure to the air ; it combines with hydrogen chloride, forming a semi-solid of the com- position C 20 H 32 -HC1. Paracajeputene 3 is produced by the action of phosphoric anhy- dride on the oil of cajeput ; it boils at 310° to 316°, dissolves in ether, but is insoluble in alcohol and turpentine oil. Diterpene 4 is obtained by heating terpine hydrate with phos- phoric anhydride or hydriodic acid ; it is a thick, oily liquid, which boils at 320° to 325°, and has a specific gravity of 0.9535 at 0°. It unites with hydrogen bromide and chloride, forming additive compounds, and also yields a yellow, amorphous nitro-product. TRITERPENES, C^. Several well characterized compounds which occur in elemi-resin belong to the class of triterpenes. When elemi-resin is washed with alcohol, the resinous substances are dissolved, and a crystal- line compound is obtained ; this has been investigated by many chemists, and is called amyrin. Vesterberg's 5 detailed investiga- tion showed that amyrin, purified by recrystallization from alcohol, consists of a mixture of two isomeric triterpene alcohols, C^H^OH. The separation of these alcohols is effected by boiling amyrin, which is obtained from elemi-resin in a yield of 16.5 per cent., with acetic anhydride, and crystallizing the resultant acetyl com- pounds from ligroine ; the crude acetyl derivative melts at about 200°. By fractional crystallization of the crude acetyl compound, two substances of different crystalline form are obtained, the one, ß-amyrin acetate, consisting of aggregates of prisms, the other, a-amyrin acetate, separating in single leaflets. Both acetates may be obtained in a condition of chemical purity by repeated recrystal- iHell and Stiircke, Ber., 1894, 1973. 2Lafont, Compt. rend., 106, 140; Ber., 1888, 138; Bull. Soc. Chim., 49, 17; Ber., 1888, 605, Ref.; Bouchardat and Lafont, Compt. rend., 107, 916; Ber., 1889, 9, Ref. sSchmidt, Jahresb. Chem., 1860, 481. * Berkenheim, Ber., 1892, 686. sVesterberg, Ber., 20, 1242; 28, 3186; 24, 3834 and 3836. TRITERPENES. 433 lization from petroleum ether or benzene. Pure a- and /?-amyrin are secured by the saponification of the pure acetates. The total amount of a-amyrin in the crude amyrin is about sixty-six to seventy-five per cent. a-Amyrin, C 30 H 49 OH, crystallizes in long, lustrous, elastic needles, which are quite readily soluble in ethyl acetate, ether, benzene and hot alcohol, but are sparingly soluble in cold alcohol and ligroine. It melts at 181° to 181.5°, and is optically dextro- rotatory, 0]^,= + 91.59°. /?-Amyrin, C 30 H 49 OH, shows a striking resemblance to the a- modification, but is more difficultly soluble in alcohol, and melts at 193° to 194°. It is dextrorotatory, [a\ D = + 99.81°. The acetates of a- and /9-amyrin have already been men- tioned. Both a- and /9-amyrin are apparently secondary alcohols. "When oxidized with chromic acid, they yield the corresponding ketones (or, possibly, aldehydes), a- and ß-amyrone, which, on treat- ment with hydroxylamine, are readily converted into oximes, C 30 H 48 :NOH. When a- or /9-amyrin is dissolved in petroleum ether and treated with phosphorus pentachloride, a- or ß-amyrilene, C 30 H 48 , is formed ; both modifications are optically dextrorotatory. Levo- rotatory a-amyrilene is obtained by treating a solution of a-amyrin in benzene with phosphorus pentoxide. By the action of bromine on a- or /9-amyrin, or their acetates, substitution products are produced. When a-amyrin acetate is subjected to the action of chromic anhydride in glacial acetic acid solution, it yields oxy-a-amyrin acetate, C 30 H 47 O(OCOCH 3 ) ; this is converted into oxy-a-amyrin, C 30 H 47 O(OH), by hydrolysis. The analogous compound of the /9-series has not been isolated in a condition of purity (Vester- berg 1 ). The properties of a- and /9-amyrin and their derivatives are given in the following table. Almost all amyrin derivatives give characteristic colors with Liebermann's Cholesterine reagent (acetic anhydride and concen- trated sulphuric acid), the bromine compounds giving a blue, and the others a violet or purple-red coloration. These colors are best shown by dissolving about one milligram of the substance in a few drops of chloroform, adding five to ten drops of acetic anhy- dride and one or two drops of concentrated sulphuric acid, and then warming very gently. i Vesterberg, Ber., 24, 3836. 28 434 THE TERPENES. According to O. Hesse/ /9-amyrin occurs as the palmitic acid ester in the wax obtained from Trujillo coca and Java coca. Palmityl-/?-amyrin, C 46 H g0 O 2 , melts at 75°, and has the specific rotatory power, [a\ D = -f 54.5°. Amyrin, C SO H W OH. Amyrin acetate, CsoH^OCOCHg. Amyrin benzoate, caococ^. Bromoamyrin, C 3 oH l8 BrOH. Bromoamyrin acetate, C 30 H 48 BrOCOCH 3 . Amyrilene, CgoH^g, pre- pared by means of phos- phorus pentachloride. Levo-o-amyrilene, C 3 o H *8) prepared by means of phosphoric oxide. o-Series. Melting point, 181° to 181.5°; slender needles ; one part of a-amyrin dissolves in 21.36 parts of 98. 3 per cent, alcohol at 19° to 19.5°. [a] D = +91.6°. Melting point, 221°; large plates. [a] fl = + 77.0°. Melting point, 192°; needles or flat prisms. Melting point, 177° to 178°; slender needles. [a] D = + 72.8°. Melting point, 268°; tab- lets or flat prisms. Melting point, 135°; very sparingly soluble in al- cohol; crystallizes from ether in splendid, thick, rhombic prisms, and sometimes separates in sphenoidal hemihedral crystals. Axial ratio, a : b : c = 0.66733 : 1 : 0.40489. [o] D = + 109.5°. Melting point, 193° to 194° ; sparingly soluble in ether, more readily in hot ligroine, and quite easily in hot ben- zene ; at 5°, however, only one part of the hy- drocarbon is soluble in fifty-nine parts of ben- zene. It separates in rhombic crystals. a: b:c = 0.789:1:0.505. [q] g = — 104.9°. /3-Series. Melting point, 193° to 194°; slender needles; one part of ^-amyrin dissolves in 36.44 parts of 98. 3 per cent, alcohol at 19° to 19.5°. [a] z ,= + 99.8°. Melting point, 236°; long prisms. [a] D = + 78.6°. Melting point, 230°; leaflets. Melting point, 182° to 186° (?); gelatinous. Melting point, 238°; prisms. Melting point, 175° to 178°; crystallizes from benzene in long, slender, rhombic prisms. a:b :c = 0.91655:1 : 0.54032. [a]„=4- 111.3°. »Hesse, Ann. Ghem., 271, 216. TETRATEREBENTENE HYDROCHLORIDE. 435 Amyrone, CäoH^O. Amyronoxime, C^H^NOH. Oxyamyrin, C 30 H 17 O(OH)+2H 2 O. Oxyamyrin acetate, C M H 17 0(OCOCH 3 ). a-Series. Melting point, 125° to 130° ; it separates from a mixture of alcohol and glacial acetic acid in crystals containing one molecule of water of crystallization; dissolves readily in ether, hot benzene and glacial acetic acid, sparingly in cold benzene and glacial acetic acid and more dif- ficultly in alcohol. Melting point, 233° to 234° ; needles, readily soluble in hot benzene, sparingly in alcohol and ether, insoluble in petroleum ether and pot- ash. Melting point, 207° to 208°; contains two mole- cules of water of crystal- lization which are slowly evolved at 100° ; readily soluble in benzene, ether and alcohol, spar- ingly in petroleum ether. [a] D = + 108.6°. Melting point, 278° ; crystallizes from ben- zene in six-sided plates, which belong to the sphenoidal - hemihedral division of the ortho- rhombic system. /3-Series. Melting point 178° to 180° ; forms nodular aggregates of small prisms which do not contain water of crystal- lization, and are readily soluble in chloroform, ether, benzene and gla- cial acetic acid, spar- ingly in ligroine and alcohol. Melting point, 262° to 263° ; leaflets, insoluble in alcohol, sparingly soluble in ligroine and ether, quite readily in hot benzene. Melting point, 240° (?). TETRATERPENES, C 40 H 64 . Tetraterebentene is formed, together with colophene, when French oil of turpentine is shaken with twenty to twenty-five per cent, of an- timony chloride at a temperature not exceeding 50° (Riban 1 ). It is a transparent, amorphous mass, and has a specific gravity of 0.977 ; it is optically levorotatory, has a conchoidal fracture, and is soluble in ether, carbon bisulphide, ligroine, benzene and turpentine oil, in- soluble in alcohol. It melts above 100°, is not volatile at 350°, and yields colophene and a terpene, C 10 H 16 , when it is distilled. Tetraterebentene hydrochloride, C 40 H 64 . HCl, is formed when hydro- chloric acid gas is led over pulverized tetraterebentene. The dihy- drochloride, C 40 H 64 *2HC1, is obtained when hydrogen chloride is passed into a well cooled, ethereal solution of tetraterebentene. The latter compound and the corresponding dihydrobromide are amorphous (Riban 1 ). iRiban, Ann. Chim. Phys. [5], 6, 40. INDEX. Absinthol=Thujone, 225 Acetaldehyde, 398 Acetic acid, 71, 129, 158, 200, 224, 264, 265, 277 Acetone, 218, 243, 392, 406 Acetoxylene, 158 oxime, 158 Acetyl bornylamine, 341 carvonienthylamine, 358, 865 dihydrocarvylamine, 358 o-Acetyl-j3, /3-dimethyladipic acid, 403 hydrogen ethyl ester, 403 semicarbazone, 403 Acetyl fencholenamine, 352 fenchylamine, 349 menthonylamine, 413 d- Acetyl menthylamine, 371 Z- Acetyl menthylamine, 368 Acetyl neobornylamine, 345 pinylamine, 337 Acid, C7H10O2, 183 dibromide, 183 C8H12O4, 47 C8H12O5, 196 CsHu02, 214 C9H16O4, 289 C10H16O2, 246 amide of, 246 CioHieO*, 233 CioHisOs, 401 C10H18O4, 264, 406 C10H15O5N, 64 C10H19O4N, 306 C12H18O3, 423 Ci5H260s, 429 calcium salt of, 429 Acid a-camphylamine oxalate, 346 Acrolein, 399 Addition-product of cineole and iodol, 326 Alcohol, C10H19OH, 316 Aldehyde, C10H16O, from camphene gly- col, 151 from myrcenol, 378 oxime of, 378 semicarbazone of, 378 Allolemonal, 405 Amidocamphene, 66 camphor, 152 2-hexahydrocymene = Carvomenthyl- amine, 290, 864 menthol, 306 menthone, 241, 305 menthonoxime, 306 hydrochloride, 306 phellandrene, 111, 874 hydrochloride, 375 mercuriochloride, 375 platinochloride, 375 sulphate, 375 Amidoterebentene, 338 hydrochloride, 339 oxalate, 339 platinochloride, 339 sulphate, 339 _p-Amidothymol, 188, 189, 211 Amine, C9H13NH2, 232 derivatives of, 232 C9H17NH2, 232 carbamide of, 232 C10H17NH2, 115 derivatives of, 115 C10H15ON, 181 C10H15O.NH2, 115 C10H21ON, 352 CioHieBr.NHOH, 270 nitroso-derivative of, 270 CioHnBr2.NHOH, hydrobromide, 270, 271 C20H35CIN2, 302 hydrochloride, 302 Aminodecoic acid, 289, 808 Ammonium a-fencholenate, 164 o-Amyrilene, 433 /3-Amyrilene, 433 Z-a-Amyrilene, 433 Amyrin, 432 derivatives, table of, 434 a- Amyrin, 433 acetate, 432 benzoate, 434 /3-Amyrin, 433 acetate, 432 benzoate, 434 palmitate, 434 Amyrol, 428 a-Amyrone, 433 /3-Amyrone, 433 a- and /3-Amyronoximes, 433 Anethol ; 156 Anhydride of cis-pinole glycol, 278, 280 of triisonitroso-methyl-cyclohex- anone, 242 Anhydrocamphenilic acid, 64 camphoic acid, 63 dimethyltricarballylic acid, 52, 55 fenchocarboxylic acid, 169 geraniol, 379, 392 hexabromide, 379 Aurantiol = Linalool, 381 Australene, 34 Auto-oxidation of carvone, 193 B Beckmann and Pleissner's " hydrated Sulegonoxime," C10H19NO2, and its erivatives, 240 Beckmann's reagent, 113 Benzoyl bornylamine, 341 campholamine, 353 437 438 INDEX. Benzoyl a-camphylamine, 346 carvoxime, 191 ■i-Benzoyl-a- carvylamine, 356 /3-carvylaniine, 356 Benzoyl-a-d-carvylamine, 355 a-l-carvylamine, 356 /3-d-carvylamine, 356 j8-l-carvylamine, 356 carylamine, 359 dlhydrocarvylamine, 358 dihydroeucarvylamine, 360 dipentene nitrosochloride, 96 fencholenamine, 352 fenchylamine, 349 hydrochlorocarvoxime, 192 limonene nitrosochloride, 76 menthylamine, tertiary, 374 neobornylamine, 345 pinylamine, 338 pulegonamine, 363 Benzyl bornylamine, 342 hydrochloride, 342 methiodide, 342 platinochloride, 342 dihydrocarveol, 211 fenchylamine, 350 hydrochloride, 350 nitroso-derivative of, 350 platinochloride, 350 Benzylidene bornylamine, 342 hydrochloride, 342 platinochloride, 342 carvone, 193 dihydrocarvone, 211 dihydrocarvoxime, 211 dihydroisocamphor, 252 eucarvone, 200 fenchylamine, 350 hydrochloride, 350 menthone, 306 hydrobromide, 306 hydrochloride, 306 menthonoxime, 306 menthylamine, 306 d-Benzylidene menthylamine, 372 Z-Benzylidene menthylamine, 369 Benzylidene menthyl carbamate, 312 nopinone, 54 pinylamine, 338 pulegone, 342 Benzyl menthol, 306 menthone, 307 menthonoxime, 307 menthylamine, 307 pulegol, 243 Bisnitroso-4-bromotetrahydrocarvone, 208 Bisnitrosocarvone, 209, 220 menthone, 304 pulegone, 342 pulegonoxime, 342 tetrahydrocarvone, 288 Bispulegone, 243 Borneo-camphor, 142 Borneol, 141 bromal derivative of, 144 chloral derivative of, 144 derivatives, table of, 149 Bornyl acetate, 143 Bornylamine, 135, 340, 343, 344 Bornylamine, acetyl derivative of, 341 acid sulphate, 341 benzoyl derivative of, 341 benzylidene derivative of, 342 derivatives, tables of, 345 formyl derivative of, 341 hydrobromide, 341 hydrochloride, 340 picrate, 341 platinochloride, 341 tartrate, 341 Bornylamines, 340 Bornyl butyrate, 143 carbamide, 342 methyl derivative of,[342 phenyl derivative of, 342 chloride, 144 Bornylene, 121 oxidation of, 121 Bornyl esters, table of, 143 ethyl ether, 144 formate, 143 iodide, 40, 145 methylcarbamide, 342 methylene ether, 144 methyl ether, 143 phenylcarbamide, 342 phenylthiocarbamide, 342 phenylurethane, 144 propionate, 143 thiocarbamide, 342 valerate, 143 xanthic acid, 144 Brominated lactone, 164, 166 Bromoamyrin, 433, 434 acetate, 433, 434 Bromocamphene, 62 2-Bromocymene, 184 Bromofenchone, 159 nitrocamphane, 66, 123 S - Bromo-a-oxyisopropyl hexenoic acid. 332 Bromopernitrosocamphor, 153 pinic acid, 56 l-Bromo-A 4 ( 8 >-terpene, 93, 271 nitrosobromide, 93, 271 A (8)-terpene, 93 nitrosobromide, 93 Bromotetrahydrocumic acid, 53 Butyryl fenchylamine, 349 d-Butyryl menthylamine, 371 Z-Butyryl menthylamine, 369 C Cadinene, 4U, 424 dihydriodide, 416 dihydrobromide, 416 dihydrochloride, 416 nitrosate, 417 nitrosochloride, 416 oxidation of, 415 Cajeputene, 85 Cajeputol = Cineole, 323 Calcium cineolate, 327 Camphane = Dihydrocamphene, 123 Camphenamine, 253 Camphene, 56, 341 alcoholate, 65 aldehyde, 60, 65 INDEX. 439 Camphene, bromo-derivative of, 62 chloro-derivative of, 62 dibromide, 62 a-dichloro-derivative of, 62 glycol, 63, 151 glycol, aldehyde from, 151 hydriodide, 61 hydrobromide, 61 hydrochloride, 61 nitrates, 65 nitronitrosite, 60 nitrosite, 60 oxidation of, 63 a-Camphene phosphorous acid, 59 ß-Camphene phosphorous acid, 59 Camphene, tribromo-derivative of, 62 Camphenilanaldehyde, 60, 65, 152 Camphenilanic acid, 65, 151 Camphenilene, 64 Camphenilic acid, 63, 65 Camphenilic nitrite, 60, 64 Camphenilone, 61, 64 alcohol, 64 alcohol, chloride of, 64 oxime, 64 semicarbazone, 64 Camphenol = Carvenone, 62 Z-Camphenol = Borneol, 142 Campnenone, 152 dibromide, 153 hydrobromide, 153 monobromo-derivative of, 153 oxime, 153 pernitroso-deriyative of, 153 dibromide = Dibromoperni- trosocamphenone, 153 Camphenylnitramine, 251 Camphenylone = Camphenilone, 61, 64 Camphocenic acid, 64 Camphocenic nitrile, 64 Camphoceonic acid, 64 Camphoic acid, 63 Camphol alcohol, 152 Campholamide, 141 Campholamine, 141, 353 benzoyl derivative of, 353 hydrochloride, 152, 353 nitrate, 353 platinochloride, 353 a-Campholenamide, 136 ß-Campholenamide, 139 o-Campholenamidoxime, 136 Campholene, 137, UO, 353 a-Campholenic acid, 136 0-Campholenic acid, 139 a-Campholenic amide, 136 ß-Campholenic amide, 139 o-Campholenonitrile, 135, 346 0-Campholenonitrile, 139, 347 Campholic acid, 141, 353 Campholic amide, 141 Camphol, instable = Isoborneol, 146 Campholonic acid, 139 Campholonitrile, 141, 353 Camphol, stable = Borneol, 146 Campholyl phenylthiocarbamide, 353 Camphopyric acids, 64, 69, 71 Camphopyric anhydride, 63, 64, 69, 71 Camphor, 133 Camphor, artificial = Pinene hydrochlor- ide, 38 condensation-products of, 141 derivatives, optical properties of, 150 Camphor dioxime, 135 Camphor, oxidation of, 134 liquid, 83 Camphoric acid, 64, 134 Camphoronic acid, 134 Camphoroxime, 135 action of nitrous acid on, 135 anhydride = a-Campholenonitrile,1^5, 346 ethyl ether of, 135 phenyl cyanate derivative of, 135 sodium salt of, 135 Camphor pinacone, 141 Camphor semicarbazone, 140 Camphoylic acid, 63 Camphrene, 134, 217 Camphydrene = Dihydrocamphene, 39, 123 o-Camphylamine, 136, 346 acid oxalate, 346 benzoyl derivative of, 346 dichromate, 346 dithiocamphylcarbamate, 347 hydrochloride, 346 mercuriochloride, 346 oxalate, 346 picrate, 346 platinochloride, 346 sulphate, 346 ß-Camphylamine, 139, 347 Campnylamines, 346 a-Camphyl phenylthiocarbamide, 347 thiocarbimide, 347 Caoutchin, 85 hydrate — Terpineol, 258 Caoutchouc, distillation of, 31, 87 Caparrapene, 428 Caparrapiol, 428 Carbanilido-carvoxime, 191 isocarvoxime, 191 Carbofenchonone, 169 dioxime, 169 monoxime, 169 Carboxyl-apocamphoric acid, 63 Caronbisnitrosylic acid, 209, 220 Carone, 219 bisnitroso-derivative of, 220 dibromide, 220 oxidation of, 222 Carone semicarbazones, 220 cis-Caronic acid, 222 anhydride, 222 trans-Caronic acid, 222 Caronoxime, 220 Caro's reagent, 300 Carvacrol, 44, 134, 179, 189, 191, 199, 207, 221 Carvacrylamine, 190, 191, 228 hydrobromide, 210 Carvanol, 219, 293 Carvanone = Tetrahydrocarvone, 219, 291, 293 Carvene = (Z-Limonene, 71, 72 Carvenol = Carvenone, 62, 219, 293 2)-cZ-Carvenolic acid, 182 440 INDEX. Z-Z-Carvenolic acid, 182 Carvenolic acid, inactive, 182 Carveuolic acids, 182 dibromides of, 183 monobasic acid, C 7 H 10 O 4 , from, 183 Carvenolides, 182 dibromides of, 182 Carvenone, 62, 134, 207, 216 benzylidene derivative of, 218 nitroso-derivative of, 217 oxidation products of, 218 semicarbazones, 217 Carvenonoxime, 217 Carveol = Carvenone, 212, 216 Carveoloxime = Carvenonoxime, 210 Carveol methyl ether, 73, 178, 197, 260 addition products of, 198 Carvestrene, 103, 359 dihydrobromide, 104 dihydrochloride, 104 ortho-, 104 pseudo-, 104 Carvol = Carvone, 178 Carvomenthene, 124, 292 hydrobromide, 125 hydrochloride, 125 Carvomenthol = Tetrahydrocarveol, 291, 365 tertiary, 293, 316 Carvomenthone= Tetrahydrocarvone,238, 254, 287 Carvomenthyl acetate, 293 Carvomenthylamine = Tetrahydrocavyl- amine, 111, 290, 864 acetyl derivative of, 365 formyl derivative of, 365 hydrochloride, 365 platinochloride, 365 tertiary, 373 benzoyl derivative of, 374 chloroaurate, 374 hydrochloride, 374 platinochloride, 374 Carvomenthyl bromide, 293 tertiary, 317 carbamide, 365 chloride, 293 iodide, tertiary, 316 phenylcarbamide, 365 phenylthiocarbamide, 365 tertiary, 374 Carvone, 74, 178, 279 and derivatives, table of, 197 benzylidene derivative of, 193 compound with acetoacetic ester, 194 dichloride, 183 dihydrodisulphonate of sodium, 193 dioxime, 193 diketone from, 193 hydrobromide, 180, 198 hydrochloride, 180 hydrogen sulphide, 179 oxymethylene derivative of, 194 pentabromides, 183 phenylhydrazone, 184 reduction products of, 194 semicarbazones, 193 semioxamazone, 193 Carvone sodium]dihydrodisulphonate, 193 semicarbazone, 193 tetrabromides, 183 tribromide, 181 Carvotanacetone, 236 hydrogen sulphide, 237 Ortho-, 237 oxaminoxime, 237 oxidation of, 237 pseudo- = Terpenone, 237 semicarbazone, 237 Carvotanacetoxime, 237 Carvoxime, 184 and derivatives, table of, 187 benzoyl derivative of, 191 carbanilido-, 191 derivatives of, 184 hydrobromide, 192 hydrochloride, 191 _ benzoyl derivatives of, 192 Carvoxime, inactive, 190 iso- 190 Carvylamines, 354, 355, 356 derivatives of, 355, 356 Carylamine, 220, 358 benzoyl derivatives of, 359 hydrochloride, 103, 859 Caryl phenylthiocarbamide, 359 Caryophyllene, 417 acetate, 420 alcohol, 417, 419 bisnitrosate, 419 bisnitrosite, 418 bisnitrosochloride, 418 bromide, 420 chloride, 420 _ dihydrochloride, 417 iodide, 420 isonitrosite, 418 nitrate, 421 nitrolamines, 419 benzylamines, 418, 419 piperidide, 419 nitrosate, 418 nitrosite, 418 nitrosochlorides, 418 Caryophyllene phenylurethane, 420 Cedar camphor = Cedrol, 423 Cedrene, 423, 424 Cedrol, 423 acetate, 424 Cedrone, 424 oxime, 424 acetate, 424 Champacol = Guaiol, 426 Chavicol, 377 Chlorhydrins, 40, 282 Chloride, C10H15CI, 208, 223 a-Chlorocamphene, 62 hydrochloride, 62 sulphonic chloride, 62 Chlorocamphydrene, 39 3-Chlorocymene, 298 2-Chlorocymene, 184 Chlorodihydrocymene, 298 fenchene, 159 phosphoric acid, 158 fenchone hydrochlorides, 158 ketones, 281, 288 INDEX. 441 Chloromethyl menthyloxide, 311 2- Chloropulegone, 242 3- Chloro-A 2 ( 48 )-terpadiene, 243 tetrabromide, 243 Chlorotetrahydrocymene, 298 Cholesterine reagent, 433 Cinene, 85 Cinenic acids, 332 derivatives of, 332 Cineole, 323 addition-product with iodol, 324, 326 with naphtol, 324 compound with phosphoric acid, 324 dibromide, 326 diiodide, 326 hydrobrontide, 325 hydrochloride, 324, 325 oxidation of, 326 Cineolic acid, active, 333 anhydride of, 834, 405 derivatives of, 333 inactive, 326, 333 amides, 328, 331 anhydride of, 328 derivatives of, 327, 328, 333 esters of, 327 oxidation of, 331 Cineolic allylamide, 328 anhydride, 328 anilide, 328 diethylamide, 328 ethyl ester, 327 methyl ester, 327 para-toluidide, 329 phenylhydrazide, 329 piperidide, 328 silver salt of, 328 Cinnamic aldehyde, 399 Cinogenic acid, 332 Citral = Geranial, 396 a = Geranial a, 400 b = Geranial b, 401 Citralidene (geranialidene) bisacety lace- tone, 405 Citrene, 71 Citriodoraldehyde, 405 Citronellal, 409 acid sodium sulphite, 409 dibromide, 410 dimethyl acetal, 411 disulphonic acid derivative, 410 monosulphonic acid derivative, 410 /3-naphthocinchonic acid, 411 hydrochloride, 411 /3-naphthyl quinoline, 411 normal sodium bisulphite, 410 oxidation of, 410 oxime, 412 phosphoric acid, 411 semicarbazone, 412 sulphonic acids, 410 Citronellamide, 412 Citronella pimelic acid, 412 Citronellic acid, 401, 410, 412 dioxy-, 412 Citronellol, 389, 394, 410 acetate, 396 chlorinated phosphoric acid ester, 395 Citronellol diphenylurethane, 396 formate, 396 hydrogen phthalate, 395, 396 oxidation of, 396 Citronellone = Citronellal, 409 Citronellonitrile, 412 Citronellylidene cyanoacetic acid, 411 Clovene, 417, 418, 421 Coca wax, 434 Colophene, 431 hydrochloride, 431 Colophonium, 35, 87 Compound, C5H9CI.OH, 33 C7H10O4N2, 111 CioHieO or CioHisO, 343 CioHieOa, 159 CloHisBr, 159 C10H22O3, 293 CioHisCh, 391 CioHsOBre, 299 C10H16N2O2, 193 C10H20N2O2, 217 CioHuBr(OCHs), 197 C10H18O.H3PO4, 324 C10H17O2.OC2H5, 401 CioHi6.2Cr02Cl2, 65 CiiHiaO, 41 C11H20NO2CI, 98 C11H17NO, 169 C12H22NO2CI, 98 Ci2H2oBrOs, 279 C16H25CIO4, 194 C20H34O, 248 C20H34O2, 254 C20H35N.HBr.Br2, 343 C24H24O2, 200 C24H26O2, 218 Condensation-product, CnHisO, 83, 98 C16H27NO2, 351 C24H28O2, 290 of eucarvone and benzaldehyde, 200 Copal resin, 35, 87 Coriandrol = Dextro-linalool, 383 m-Cresol, 246 Cubeb camphor, 424 Cubebene, 424 Cumic acid, 122 Cuminaldehyde, 122 Cuminyl alcohol, 122, 205 Cupric menthylxanthate, 312 Cuprous menthylxanthate, 312 Cyclodihydromyrcene, 379 dibromide, 379 ketonic acid from, 379 Cyclogeranial, 403, 404 derivatives of, 404 Cyclogeranialidene cyanoacetic acids, 404, 405 Cyclogeranic acids, 402, 403, 405 derivatives of, 402 Cyclogeraniolenes, 404 Cyclogeranionitriles, 403, 404 Cycloheptylenamine, formyl derivative of, 244 Cyclolinalolene, 380, 130 Cymene, 85, 160, 398 Cymylhydroxylamine, 189, 190 442 INDEX. D Decenoic acid = Menthonenic acid, 289, 302, 303 Decoic acid, 303 amide, 303 Dextro-linalool, 383 menthone, 315 Dextrorotatory menthone, 297 Diacetate of glycol, CioHi8(OH) 3 , 391 Diamidophellandrene, 375 hydrochloride, 376 platinochloride, 376 salts of, 376 Diamine, 306 hydrochloride, 306 Diaterpenylic acid, 196 Diaterpenylic lactone = Terpenylic acid, 196 Diazo-camphor, 152 Dihasic acid, C9H16O4, 295 Dibenzoyl dihydrocarvyldiamine, 358 Dibenzylidene menthenone, 251 alcohol from, 251 Diborneolic formal, 146 Dihornylaminej 343 hydrochloride, 343 isomeride of, 343 nitrate, 343 nitrite, 343 platinochloride, 343 Dibornylthiocarbamide, 342 Dibromide from fenchyl alcohol, 173 1, 6, 2, 8-Dibromodioxyhexahydrocymene, 277 Dihromomenthone, 299 oxime, 299 Dibromopernitrosocamphor, 153 4, 8-Dibromoterpen-l-ol, 270 acetate, 93, 270 1, 8-Dibromotetrahydrocarvone, 221 Dicarboxylic acid, CnHisOi, 169 Dicarvelones, 194, 195, 212 dihydrobromides, 195 oximes, 195 acetyl derivatives of, 195 phenylhydrazones, 195 Dichloride from fenchyl alcohol, 173 a-Dichlorocamphene, 62 Dichlorocarvone, 183 Dichlorodipentene, 91 dibromide, 91 dihydrochloride, 91 hydrochloride, 90 nitrolanilide, 91 piperidide, 91 nitrosochloride, 91 Dichlorotetrahydrocarvone, 221 Dicinene, 432 Diethyl hexamethylene, 132 alcohol, 132 iodide, 132 ketone, 132 Dieucarvelone, 196, 200 isomeride of, 196 oxime, 196 phenylhydrazone, 196 Difenchone, 170 Difenchyloxamide, 349 thiocarbamide, 349 Dihydriododipentenes, 94 Dihydrobromodipentenes, 91 Dihydrocamphene, 123 Dihydrocampholene, 138 Dihydrocampholenimide, 139 Dihydrocampholenolactone, 136, 140 Dihydrocarveol, 184, 212, 358 acetic acid, 211 ethyl ester, 211 hydrobromide, 214 oxidation of, 214 Dihydrocarvone, 155, 194, 206 acid sodium sulphite, 206 benzylidene derivative of, 211 dibromide, 207, 208, 221 dichloride, 209, 221 ketone-glycol from, 212 semicarbazone, 212 hydrobromide, 207, 220 hydrochloride, 208 oxidation of, 212 oxymethylene derivative'of, 211 semicarbazone, 211 tribromide, 209 Dihydrocarvoxime, 209 hydrobromide, 210 isomeride of, 210 Dihydrocarvyl acetate, 214 hydriodide, 214 Dihydrocarvylamine, 112, 184, 188, 213, 856 acetyl derivative of, 358 benzoyl derivative of, 358 dihydrochloride, 357 formyl derivative of, 357 hydrochloride, 213, 857 oxalate, 358 sulphate, 358 Dihydrocarvyldiamine, 358 derivatives of, 358 Dihydrocarvyl methyl xanthate, 213 phenylcarbamide, 358 phenylthiocarbamide, 358 phenylurethane, 213 Dihydrochlorodipentenes, 89 dichloride, 91 Dihydrocuminyl alcohol, 122 Dihydrocumic acid, 54 Dihydrocymene, 22, 27 Dihydrodicamphene, 123 Dihydroencarveol, 200, 223, 224 acetate, 224 chloride, 224 Dihydroeucarvone, 223 nitroso-derivative of, 223 oxidation of, 223 semicarbazone, 223 Dihydroeucarvoxime, 223 hydriodide, 223, 293, 359 Dihydroeucarvylamine, 223, 359 benzoyl derivative of, 360 hydrochloride, 360 platinochloride, 360 Dihydroeucarvyl phenylcarbamide, 360 thiocarbamide, 360 Dihydrofencholene, 164 Dihydrofencholenamide, 167 Dihydrofencholenic acid, 167 Dihydrofencholenic lactam = ß- Isofen- chonoxime, 168 INDEX. 443 Dihydrofencholenonitrile, 167 Dihydroisocamphor, 252 acid sodium sulphite, 252 benzylidene derivative of, 252 semicarbazone, 252 Dihydroisothujol = Thujamenthol, 236, 295 Dihydromyrcene, 379 cyclo-, 379 diketone from, 379 keto-glycol from, 379 Dihydropseudocumene, 231 Dihydroxylene, meta-, 330 Diisonitroso-methyl-cyclohexanone, 242 diacetate, 242 Diisoprene, 85 Diketone, CsHuOz, 211, 212 dioxime of, 211, 212 semicarbazone of, 212 CioHuOa, 193 1, 3-Diketone, C10H16O2, 310 dioxime of, 310 Dimentholic formal; 310 Dimenthyl, crystalline, 313 liquid, 313 methylal, 310 a, a-Dimethyl adipic acid, 402 ß, j8-Dimethyl adipic acid, 402 gem-Dimethyl adipic acid, 294 1, 2, 4-Dimethyl ethyl benzene, 120 Dimethyl fenchylamine hydriodide, 349 a, a-Dimethyl glutaric acid, 403 2, 6-Dimethyl heptan-5-onic acid, 218 oxime, 218 Dimethyl heptenol, 392 isopropyl butylene oxide, 232 S-Dimethyl laevulinic acid, 231 to-Dimethyl laevulinic acid, 231 oxime, 231 5- or w-Dimethyl laevulinic methyl ketone, 230, 233 oxime, 231 Dimethyl malonic acid, 158, 163, 294 2, 6 - octadiene-2, 6 - acid-8 = Geranie acid, 407 2, 7-ol-6 = Linalool, 383 2, 6-al-8 = Geranial, 407 2, 6-0I-8 = Geraniol, 383, 892 2, 6-Dimethyl octane-2, 8-0I, 894, 413 3-onoic acid, 310 Dimethyl-2, 6-octene-2-al-8 = Citronellal, 410 0I-8 = Citronellol, 396 octylene glycol, 303, 394, 413 2, 6-oximido-3-octanic acid = Menth- oximic acid, 304, 305, 310 as-Dimethyl succinic acid, 55, 64 gem-Dimethyl succinic acid, 120, 200, 223, 224, 294 Dimethyl thujylamine, 361 hydrochloride, 361 nitrate, 361 platinochloride, 361 tricarballoylformic acid, 55 tricarballylic acid, 51, 55, 64, 158 gem - Dimethyl trimethylene - 1, 2-dicar- boxylic acid, 222 Dinitroeudesmole, 286 Diosphenol, 315 Dioxime, C<)Hh(NOH)2, 211 CioHu(NOH) 2 , 193 Dioxycamphoceanic acid, 64 Dioxycitronellic acid, 412 a-Dioxydihydrocampholenic acid, 136, 138 jS-Dioxydihydrocampholenic acid, 139 Dioxydihydrocyclogeranic acid, 402 Dipentene, 85, 213, 358, 377 derivatives, table of, 100 dichloride, 91 dihydriodides, 94 dihydrobromides, 91 dihydrochlorides, 89 hydrochloride, 89 nitrolamines, 96 a-Dipentene nitrolanilide, 96 nitroso-derivative of, 97 P-Dipentene nitrolanilide, 97 nitroso-derivative of, 97 a-Dipentene nitrolbenzylamine, 97 nitrolpiperidide, 96 0- Dipentene nitrolpiperidide, 96 Dipentene nitrosochlorides, 95 benzoyl derivatives of, 96 Dipentene nitrosate, 96 tetrabromide, 94 tetrachloride, 91 tribromo-derivative of, 92 trichloro-derivative of, 90 Diterpene, 432 Diterpenes, 431 Diterpilene, 432 hydrochloride, 432 Dryobalanops camphora, 142 E Elemi resin, 87, 108, 432 Essence of resin, 87 Ethoxybromocarvacrol, 227 Ethyl bornyl ether, 144 camphene, 65 Ä-chloro-o-methoethylol-5-hexoate,332 cineolic ester, 327 hydrogen cineolate, 327 isobornyl ether, 148 menthane, 314 Eucalyptene, 34 Eucalyptol, 324 Eucarvone, 181, 198 benzylidene derivative of, 200 oxidation of, 200 phenylhydrazone, 199 semicarbazone, 200 Eucarvoxime, 199 Eudesmol, 285 dibromide, 286 dinitro-derivative of, 286 oxidation of, 286 Eugenol, 377 Euterpene, 120, 224 dihydrobromide, 120 F Fenchelene, 120 Fenchene, 66, 171 X>--methoxybenzylidene derivative of, 351 neutral oxalate, 348 nitrate, 348 nitrite, 348 oxalate, 348 o-oxybenzylidene derivative of, 351 p-oxybenzylidene derivative of, 351 picrate, 348 platinochloride, 348 propionyl derivative of, 349 sulphate, 348 table of compounds, 351 tartrate, 348 Fenchyl acetate, 172 benzoate, 172 benzylamine, 350 nitroso-derivative of, 350 bromide, 173 carbamide, 349 Z>-c£-Fenchyl chloride, 173 D-l- Fenchyl chloride, 173 Fenchyl chloride, secondary, 173 tertiary, 67, 172 formate, 171 hydrogen phthalate, 172 iodide, 173 o-methoxybenzylidene amine, 351 p-methoxybenzylidene amine, 351 methylamine, 349 nitroso-derivative of, 350 oxamide, 349 o-oxybenzylidene amine, 351 p-oxybenzylidene amine, 351 phenylthiocarbamide, 349 phenylurethane, 172 thiocarbamide, 349 Formyl bornylaminej 341 carvomenthylamine, 365 dihydrocarvylamine, 357 d-Formyl menthylamine, 371 Z-Formyl menthylamine, 368 neobornylamine, 345 Furfuro-pinylamine, 338 -fencholenamine, 352 G Galipene, 428 hydrobromide, 428 Galipol, 428 Geranial, 377, 396, 405 acid sodium sulphite, 397 anilide, 399 -(citral-) a, 400 a, semicarbazone, 400 b, 401 b, naphthocinchonic acid, 401 b, oxime, 401 b, semicarbazone, 401 dihydrosulphonic acid derivatives,398 Geranialidene bisacetylacetone, 405 cyanoacetic acid, 404, 405 INDEX. 445 6-Geranialidene cyanoacetic acid, 405 Geranial-P-napthocinchonic acid, 399 hydrochloride, 399 Geranial, oxidation of, 405, 406 oxime, 400 phenylhydrazone, 399 polymeride of, 405 semicarbazones, 400 sodium bisulphite, normal, 398 hydrosulphonate, 398 tetrabromide, 398 Geranie acid, 401 a- and ß-cyclo-, 402 Geraniol, 383, 387 _ calcium chloride derivative of, 387, 388, 890 oxidation of, 392 Geraniolene, 402 tetrabromide, 402 Geranionitrile, 401 amidoxime of, 404 Geranyl acetate, 392 anilide, 399 bromide, 391 dihydrobromide, 391 Chloride, 891, 395 diphenylurethane, 393 tetrabromide, 393 hydrogen phthalate, 390, 893 silver salt of, 393 tetrabromide, 393 succinate, 390 iodide, 391 phenylhydrazone, 399 Geronic acid, 402, 404, 405, 408 semicarbazone, 404 Glycerol, C 9 Hi 7 (OH)3, 233 Glycol, C6H 8 Brj(OH)i, 32 C 1 oHi 6 (OH)2, 263 diacetate, 263 CioHi 8 (OH)2, 207, 214, 220, 391 diacetate, 214 K 391 C10H20O2, crystalline, 315 liquid, 315 Gonorol, 426 Guaiol, 426 acetate, 426 Guttapercha, distillation of, 31 H Hemiterpenes, 17, 31 Heptylenamine, cyclo-, 244 Hesperic acid, 83 Hesperidene, 71 trans-Hexahydro-1, 3, 5-carvacrol, 315 Hexahydrocymene, 18, 130, 131, 309, 322 Hexahydro-meta-toluidine, formyl de- rivative of, 244 Homocamphoric acid, 133 Homolimonene, 211 Homoterpenoylformic acid, 54 oxime of, 55 Homoterpenylic acid, 54, 55 Humulene, 421 bisnitrosite, 422 isonitrosite, 422 nitrolamines, 422, 423 nitrolbenzylamine, 422, 423 hydrochloride, 422 Humulene nitrolpiperidide, 422, hydrochloride, 422 platinochloride, 422 nitrosate, 422, 423 nitrosite, 422, 423 nitrosochloride, 422, 423 Hydrated pulegonoxime = Pulegone hy- droxylamine, 239, 240 acetyl derivative of, 241 benzoyl derivative of, 241 hydrochloride, 241 oxalate, 241 Hydrazocamphene, 65 Hydriododihydroeucarvoxime, 223, 293, 359 Hydriodofenchonoxime anhydride, 162 Hydro-aromatic acids, behavior of, 215 Hydrobromocarvone, 180, 198 dibromide, 181 keto-amine of, 181 phenylhydrazone, 181 Hydrobromocarvoxime, 181, 192 dihydrocarveol, 214 dihydrocarvone, 207 dihydrocarvoxime, 210 dipentene dibromide, 92 fencholenic acids, 164, 166 fenchonoxime anhydride, 162 pinole dibromide, 278 pulegone, 239 pulegonoxime, 239 Hydrocarbon, C9H16, 245 nitrosochloride of, 245 CioHu, 358 CioHie, 379 CioHis, 130, 380 C10H20, 131, 315 C10H22, 379 C15H28, 416 C17H22, 211 C30H50, 421 Hydrocarbons, CioHis, 123 C10H20, 130 Hydrochlorocarvone, 180 phenylhydrazone, 180 Hydrochlorocarvoxime, 191 benzoyl derivative of, 192 Hydrochlorodihydrocarvone, 208 Hydrochlorodipentene, 89 dichloride, 90 nitrolamines, 97 anilide, 97 benzylamine, 98 p-toluidide, 98 nitrosate, 97 nitrosochloride, 97 Hydrochlorofencholenamide hydrochlor- ide, 352 fencholenic acid, 164 fenchonoxime, 161 anhydride, 162 Hydrochlorolimonene, 80 nitrolamines, 82 anilide, 82 benzylamine, 82 nitrosate, 81 nitrosochloride, 81 Hydrochloronitrosodipentene ethyl ether, 446 INDEX. Hydrochloronitrosodipentene methyl ether, 98 Hydrochloropulegone, 239 Hydrocyanic acid, 158 Hydroxycamphene, 66 Hydroxycamphoronic acid, 51 Hydroxylammocarvoxime, 192 dibenzoyl derivative of, 192 diphenylcarbamide, 193 diphenylthiocarbamide, 193 picrate, 192 I Inactive carvoxime, 96, 190 menthol, 312, 315 pulegone, 239 Instable camphol = Isoborneol, 146 Ionone, commercial, 407 o-Ionone, 407 oxime, 407 semicarbazone, 407 /3-Ionone, 405, 408 oxime, 408 semicarbazone, 408 Irone, 408 Isoamidocamphor, 136, 139 Isoborneol, 146 bromal derivative of, 149 chloral derivative of, 149 derivatives, table of properties, 149 Isobornyl acetate, 148 chloride, 150 Isobornylene, 121 Isobornyl ethyl ether, 148 formate, 148 methylene ether, 148 methyl ether, 148 phenylurethane, 149 Isobromopernitrosocamphor, 153 Isobutyl camphene, 65 Isobutylidene diaceto-acetic ester, 27 Isobutyric acid, 158 Isobutyryl ethyl methyl ketone, 230 ketoxime, 231 methyl ketopentamethylene, 310 y-Isobutyryl ß-methyl valeric acid = Oxy- menthylic acid, 129, 310 Isocamphenilanic acid, 65 Isocamphenol, 171 Isocamphenone, 153 oxime, 153 Isocamphol, 58, 146 Isocamphopyric acid, 63 Isocamphor, 166, 251 bisnitrosochloride, 252 dihydro-, 252 oxime, 166, 252 semicarbazone, 166, 252 tetrahydro-, 252 J3-Isocamphor, 253 phenylurethane, 253 Isocamphoranic acid, 52 Isocamphorenic acid, 52 Isocamphorone, 139 Isocamphoronic acid, 51, 55, 158 Isocamphoroxime = a-Campholenamide, 136 Isocarveol = Pinocarveol, 201, 202 Isocarvone = Pinocarvone, 201 Isocarvoxime, 190 benzoyl derivative of, 191 carbanilido-, 191 Isocedrol, 424 benzoate, 424 Isodihydrocamphene, 124 Isofencholenyl alcohol, 163, 176 a-Isofenchonoxime, 162 /3-Isofenchonoxime = Dihydrofencholenic acid lactam, 163 ß-Isofenchonoxime, salts of, 163 Isofenchyl alcohol, 68, 174 acetate, 174 derivatives, table of, 175 formate, 175 hydrogen phthalate, 175 ketone from, 175 alcohol from, 175 oxime, 175 phenylurethane, 175 Isogeronic acid, 402, 403, 404, 408 semicarbazone, 403, 404 Isoketocamphoric acid, 51 Isomenthol, 309, 314 Iso-Z-menthonoxime, 301 Isomenthyl benzoate, 314 Isomeric terpineol, m. p. 69° to 70° = A4(8)_Terpen-l-ol, 269 m. p. 32° to 33° = A 8 < 9 >-Terpen- l-ol, 273 nitrolamines, 274 piperidide, 274 nitrosochloride, 274 oxy-ketone from, 274 phenylurethane, 274 thujonoxime, m. p. 90°, 228 thujylamine, 361 Isonitrosocamphor, 152 menthone, 307 pulegone, 242 Isopernitrosofenchone, 166, 252 Isopinole dibromide, 253, 279 Isoprene, 31 dibromhydrin, 33 dibromide, 32 dichlorhydrin, 32 dihydrobromide, 32 dihydrochloride, 32 hydrobromide, 32 alcohol from, 32 • hydrochloride, 32 alcohol from, 32 dibromide, 32 tetrabromide, 32 a-Isopropyl glutaric acid, 252 anhydride, 253 anilide, 253 5-Isopropyl heptan-2-onic acid, 288 oxime, 288 a-Isopropylidene-AV-hexenoic acid, 333 /3-Isopropyl laevulinic acid, 236, 295 Isopropyl succinic acid, 236, 237, 288, 289 Isopulegol, 247, 410 acetate, 247 Isopulegone, 247, 248 a-Isopulegone, 249 ß-Isopulegone, 248 INDEX. 447 Isopulegone derivatives, table of, 250 semicarbazones, 249 Isopulegonoximes, 249 Isosantalenes, 427 Isoterebentene, 85 a-Isotetrahydrocarvoxime, 289 0-Isotetrahydrocarvoxime, 290 Isothujaketonic acid, 236 oxime, 236 semicarbazone, 236 Isothujamenthonoxime, 294 Isothujene, 119, 360 Isothujolacetic acid, 235 Isothujone, 157, 235 oxidation of, 236 oxime, 228, 235 semicarbazones, 235 Isothujylamine, 362 hydrochloride, 362 nitrate, 362 Isothujyl carbamide, 362 phenylcarbamide, 362 phenylthiocarbamide, 362 Isovaleric acid, 392 K Keto-amine, 181 derivatives of, 181 Ketodihydrocymenes, 22 Ketohexahydrocymeue, 19, 24 «-Keto-isocamphoronic acid, 55 Keto-lactone, CioHi 6 03, = Methoethylhep- tanonolide, 263 oxime, 264 semicarbazone, 264 = Methyl ketone of homoter- penylic acid, 221, 267 CioHieOs, 48, 49, 52, 295 oxime, 295 Ketomenthone, 307 oxime, 308 Ketone, CioHuO, 212 CioHisO, 155, 212, 253 oxime, 253 Ketone alcohol, C10H16O2, 47 oxime, 47 C10H17O.OH, 129 acetate, 207 oxime, 129 phenylurethane, 129 Ketone glycol, 212 semicarbazone, 212 Ketonic acid, C8H12O3, 71 derivatives of, 71 C9H12O3, 403 semicarbazone, 403 C10H18O3, 294, 295 oxime, 294 semicarbazone, 294, 295 Keto-oxydihydrocyclogeranic acid, 402 semicarbazone, 402 Ketopentamethylenes, 133 pinic acid, 39 hydrazone, 39 oxime, 39 Ketotetrahydrocymenes, 20 Keto-terpine, 209 L Lactone, C7H12O3, 230 C10H16O2, 169, 246 ^-Lactone, C10H18O2, 300 derivatives of, 300 Lactonic acid, C7H10CU, 243 C10H16O4, 218 Laevulinic acid, 392, 406 Laurene, 34 Lavendol = Linalool, 381 Ledene, 425 chloride, 425 Ledum camphor, 425 Lemonal = Geranial, 396 Lemonol = Geraniol, 384, 389, 392 Levo-camphenol, 58, 142 Levorotatory menthone, 297 Licareol = Linalool, 381 Licarhodol = Geraniol, 387, 389 Z-Licarhodol, 405 Liebermann's Cholesterine reagent, 433 Limonene, 71, 213 chloro-derivative of, 80 derivatives, optical properties of, 85. 86 hydrochloride, 80 nitrolamines, 76 anilides, 77 table of, 78 benzylamines, 79 piperidides, 79 nitrosate, 76 nitrosobromide, 76 nitrosochlorides, 74 and compounds derived from them, table of, 186 nitrosochlorides, benzoyl derivatives of, 76 ortho-, 84 oxidation products of, 83 pseudo-, 84, 85, 114 tetrabromide, 72, 73, 197] Limonenol, 83, 203 tetrabromide, 203 Limonenone, 204 oxime, 204 Limonetrol, 84, 334 Linalolene, 380, 385 cyclo-, 380 Linalool, 377, 381 dextro- = Coriandrol, 383 oxidation of, 386 properties, table of, 382 sodium salt of, 384 Linalyl acetate, 386 butyrate, 387 d-Linalyl chloride, 386 Linalyl chlorides, 385 d-Linalyl iodide, 386 Linalyl propionate. 387 sodium phthalate, 384 valerianate, 387 M Massoyene, 34 Matricaria camphor, 133 Mentha camphor, 308 Menthadienes, 24 Menthandiol-3, 8, 248 448 INDEX. Menthane = Hexahydrocymene, 24, 130, 131 cis-Menthane-1, 2-dichlor-6, 8-diol, 40, 282 Menthane, meta-, 131 Menthan-2-ol = Carvomenthol, 291 3-ol= Menthol, 308 2- one = Carvomenthone, 287 3- one = Menthone, 295 1, 2, 6, 8-tetrol, 277, 282 triol, 266 Menthene, 24, 126, 308, 313, 315, 370, 372 A8(9)-Menthene-1, 2-diol, 263 diacetate, 263 A^Menthene-ö^-diol = Pinole hydrate, 277 A 6 -Menthene-2,8-diol= Pinole hydrate, 277 Menthene glycol, 129, 323 diacetate, 129 monoacetate, 129 terpene, CioHi6, from, 129 Menthene hydriodide, 314 hydrobromide, 314 hydrochloride, 313 meta-, 130 nitrolbenzylamine, 128 nitrosate, 128 nitrosochloride, 128 A 6 -Menthene-2-one, 181, 253 dioxime, 254 hydrogen sulphide, 254 oxaminoxime, 254 oxalate, 254 oxime, 254 semicarbazone, 254 Menthenone, 129, 250, 304 alcohol from, 251 _ dibenzylidene derivative of, 251 hydrogen sulphide, 251 nitroso-derivative of, 251 phenylhydrazone, 251 pinacone from, 251 Menthobisnitrosylic acid, 304 Menthocitronellal, 303, 409_ ß-naphthocinchonic acid, 409 semicarbazone, 409 Menthocitronellol, 303, 380, 393, 413 acetate, 394 nitrous acid ester, 394 Menthoglycol, 248, 410 monoacetate, 248 Menthol, 239, 308, 368, 370, 372 cis-symmetrical, 315 inactive, 312, 315 iso-, 309, 814 liquid, 308 oxidation of, 309 sodium salt of, 310 solid, 308 benzoate, 308 sym-, 315 tertiary, 317 Menthonaphthene, 131, 309 Menthone, 238, 239, 295, 372 a-Menthone, 307 Menthone amine, 307 Menthone, benzylidene derivative of, 306 bisnitroso- derivative of, 304 bisnitrosylic acid, 304 carboxylic acid, 307 chloro-derivative, C10H17CI, 298 Menthone, chloro-derivative, CioHisCh, 298 dextro-, 315 dextrorotatory, 297 dibromo-derivative of, 299 dicarboxylic acid, 307 inactive, 297 levorotatory, 297 Menthonenic acid = Decenoic acid, 289, 302, 303 amide, 302 Menthone, oxidation of, 299 oxymethylene derivative of, 305 pernitroso-derivative of, 304 pinacone, 307, 308 a-Menthone semicarbazone, 307 Menthone semicarbazones, 303 semioxamazone, 303 sym-, 308 semicarbazone, 308 sodium bisulphite, 308 Menthonitrile, 302, 393, 413 cZ-Menthonoxime, 301 Z-Menthonoxime, 300 d-Menthonoxime hydrochloride, 301 Z-Menthonoxime hydrochloride, 300 Menthonyl acetate, 394 alcohol = Menthocitronellol, 393, 394, 413 aldehyde=Menthocitronellal, 303, 409 amine, 303, 380, 393, 418 acetyl derivative of, 413 acid oxalate, 413 hydrochloride, 413 oxalate, 394, 413 oxamide, 413 oxyhydro-, 303, 393, 413 platinochloride, 413 Menthoximic acid, 304, 310 Menthyl acetate, 311 acetoacetate, 311 phenylhydrazone, 311 cZ-Menthyl allylthiocarbamide, 372 d- (eis-) Menthylamine, 370 Z- (trans-) Menthylamine, 301, 368 d- (eis-) Menthylamine, acetyl derivative of, 371 benzylidene derivative of, 372 butyryl derivative of, 371 formyl derivative of, 370, 371 hydriodide, 371 hydrobromide, 371 hydrochloride, 371 o-oxybenzylidene derivative of, 372 propionyl derivative of, 371 Z-(trans-) Menthylamine, acetyl deriva- tive of, 368 benzylidene derivative of, 369 butyryl derivative of, 369 formyl derivative of, 368, 370 hydriodide, 368 hydrobromide, 368 hydrochloride, 368 nitrite, 368 o-oxybenzylidene derivative of, 369 propionyl derivative of, 369 Menthylamines, 298, 365 and derivatives, optical properties of, 373 INDEX. 449 Menthylamine, tertiary, 374 benzoyl derivative of, 374 chloroaurate, 374 hydrochloride, 374 platinochloride, 374 Menthyl benzoyl ester, Sil, 314 bromide, 314 tertiary, 317 butyrate, 311 carbamate, 312 benzylidene derivative of, 312 d-Menthyl carbamide, 372 Z-Menthyl carbamide, 369 Menthyl carbonate, 312 chloride, 313 dixanthate, 127, SIS ethyl ether, 311 Z-Menthyl ethyl nitrosamine, 369 Menthyl iodide, 314, 315 inactive, 315 tertiary, 317 Z-Menthyl isobutyl nitrosamine, 369 Menthyl methyl ether, tertiary, 317 Z-Menthyl methyl nitrosamine, 369 Menthyl methyl xanthate, 312 phenyl carbamate, 312 d- Menthyl phenyl carbamide, 372 Z-Menthyl phenyl carbamide, 369 d-Menthyl phenyl thiocarbamide, 372 Z-Menthyl phenyl thiocarbamide, 369 Menthyl phenyl thiocarbamide, tertiary, 374 phenylurethane, 312 phthaloxyl ester, 312 phthalyl ester, 312 Z-Menthyl propyl nitrosamine, 369 stearate, 310 succinoxyl ester, 311 succinyl ester, 311 d-Menthyl trimethyl ammonium hydrox ide 372 Z-Menthyl trimethyl ammonium hydrox- ide, 370 . „, d-Menthyl trimethyl ammonium iodide, 372 Z-Menthyl trimethyl ammonium iodide, 369 . Z-Menthyl trimethyl ammonium truodide, 370 urethane, 312 xanthic acid, 312 methyl ester, 312 salts of, 312 Meta-australene, 431 dihydroxylene, 330 menthane = 1, 3-Methyl isopropyl cy- clohexane, 131 menthene = 1, 3-Methyl isopropyl cy- clohexene, 130 oxyhexahydrotoluene, 245 oxy-para-toluic acid, 215 terebentene, 431 Methoethene-5-hexene-2-acid-6, 333 Methoethylheptanonolide, 52, 268, 266, 323 3-Metho-ethyl-2-hexene-dioic acid, 230 Methoethylol-5-hexene-2-acid-6 = <*-Oxy- isopropyl-A^-hexenoic acid, 332 Methoxybromocarvacrol, 227 29 Methoxybromocarvacrol acetyl ester, 227 methyl ether 227 o-Methoxybenzylidene fenchylamine, 351 p-Methoxybenzylidene fenchylamine, 351 Methyl adipic acid, 129 0-Methyl adipic acid, 243, 299, 303, 310, 396, 412 Methyl amine, 364 2-aminoethyl-3-pentolide, 265 bornyl carbamide, 342 bornyl ether, 143 chavicol, 377 cineolic ester, 327 cyclohexanol, 245 l-cyclohexanol-6-methyl-acid-4, 215 cyclohexanone, 239, 244 oxime, 245 semicarbazone, 245 dihydrocarveol xanthate, 213 dihydrocarvyl xanthate, 74 l-dimethyl-5-cyclohexene-l-methyl- acid-6, 403 Methylene bornyl ether, 144 isobornyl ether, 148 Methylenic acetal of borneol = Diborne- olic formal, 146 of menthol = Dimentholic formal, 310 Methyl^-ethyl-S-heptanon-ö-olid-l, 3 1 , 48, 49, 52, 263, 264, 266 oxime, 264 3-Methyl-ethyl-2-heptene-6-onoic acid, 229 Methyl-l-ethyl-on-4-cyclohexanol-6, 215 Methyl eugenol, 377 fenchimine iodide, 167 fenchylamine, 349 hydriodide, 349, 350 hydrochloride, 350 nitroso-derivative of, 350 -gem-dimethyl cycloheptenone, 223 a-Methyl glutaric acid, 218 Methyl-2-heptene-2-on-6, 407 heptenol, 330, 392 oxide, 331 heptenone = Methyl hexylene ketone, 380, 398, 405 heptenoncarboxylic acid, 406 2- Methyl heptone-3, 6-dione, 230 oxime, 231 Methyl heptylene carbinol, 177, 282 ketone, 231 benzylidene derivative of, 231 oxime, 232 semicarbazone, 231 3- Methyl hexan-3-onoic acid, 231 Methyl hexenone, 244 hexylene carbinol, 177, 830, 392, 406 ketone, 329, 330, 405 derivatives of, 330 oxide, 331 isobornyl ether, 148 cis-1, 3-Methyl isopropyl cyclohexanol-5, 315 hexanone-5, 308 hexane, 130 hexene, 131 3-Methyl isopropyl-A 2 -cyclohexenone car- boxylic acid, 253 Methyl isopropyl hexahydrofluorene, 307 450 INDEX. 3-Methyl - 6 - isopropyl-A 2 -keto-R-hexene, 316 2-Methyl isopropyl pyrroline, 231 Methyl isopropyl trioxyhexahydroben- zene = Trioxyterpane, 262 ketone of homoterpenylic acid, 221, 267 /3-Methyl ketopentamethylene, 243 Methyl menthylxanthate, 312 mercaptan, 313 2-Methyl-3-menthene heptane-6-one, 232 2-Methyl - 3 - methyl-ol-heptan-6-one-3-ol, 233 1 - Methyl-4-propenyl - dihydroresorcinol, 193 Methyl pulegenate, 245 pulegonamine, 363 Flatinochloride, 364 „ pyrrolidine, 31 Methyl terpine, 318 acetate, 318 Monobasic acid, C9H16O, 331 methyl ester, 331 Monobromocamphene, 62 camphenone, 153 dipentene dihydrobromide, 92 Monochloro dipentene dihydrochloride, 90 menthone, 304 Monoketazocamphadione, 152 camphor quinone = Diazocamphor, 152 Myrcene, 377 oxidation of, 378 Myrcenol, 378, 383 oxidation of, 378 Myrcenyl acetate, 378 N Naphthenes, 132 Neobornylamine, 344 acetyl derivative of, 345 benzoyl derivative of, 345 derivatives, table of, 345 formyl derivative of, 345 hydrochloride, 344, 345 platinochloride, 345 picrate, 345 Neobornyl carbamide, 345 phenylcarbamide, 345 Nerolol = Linalool, 381 Ngai camphor, 142 Ngai fen, 150 Nitrocamphane, 123 Nitrocamphene, 66 Nitrofenchone, 158 Nitromenthone, 241, 305 Nitrophellandrene, 111, 374 Nitroxylene, meta-, 330 Nitrosobenzyl fenchylamine, 350 Nitrosocarvenone, 217 Nitrosodihydroeucarvone ; 223 Nitrosodipentene = Inactive carvoxime, 96, 190 _ o-nitrolanilide, 97 P-nitrolanilide, 97 Nitrosolimonene nitrolanilides, 79 Nitrosomenthene, 129, 251 Nitrosomenthenone, 251 Nitrosomenthone, 241 Nitrosomethyl fenchylamine, 350 Nitrosopinene, 43, 154, 202, 336 dibromide, 155 Nitrosopulegone, 242 Nitrosoterpene = Carvoxime, 184 Nitroterebentene, 339 Nomenclature, 23 Nopic acid, 53 Nopinole glycol, 41, 282 diacetate, 41, 282 Nopinone, 54 benzylidene derivative of, 54 oxime, 54 semicarbazone, 54 Norpic acid, 47, 56 aldehyde, 56 semicarbazone, 56 silver salt of, 56 O Ocimene, 379 Oil of absinth = Oil of wormwood, 87,, 108, 225, 415 andropogon, 108 schoenanthus, 389 angelica, 108 angostura bark, 415, 428 anise, star, 35, 108 artemisia (Artemisia barrelieri), 225' asafetida, 415 balm, 397 basil, sweet = Oil of basilicum, 34, 35, 324, 379, 381 basilicum, French, 35, 324, 381 German, 34, 324, 379, 381 bay, 35, 108, 377, 397 bergamot, 71, 87, 381, 382, 386 betel leaves, 414 bitter fennel, 108 Blumea balsamifera, 142 buchu leaves, 130, 307, 315 Barosma betulina, 315 serratifolia, 315 cade, 414, 415 cajuput, 35, 258, 323, 432 camphor, 35, 57, 87, 108, 257, 324, 414 Canadian pine, 142 cananga, Java, 381 Canella alba, 35, 324, 417 caparrapi, 428 caraway, 71, 178, 185, 219 cardamom, 87, 112, 257, 266, 324 Carlina acaulis, 430 cedar wood, 423 cedro, 397 celery seed, 71 champaca wood, 426 cheken-leaves, 35, 323 chenopodium = Oil of wormseed, American, 87, 432 cinnamon, 108, 324 citron = Oil of lemon, 34, 57, 71, 108, 381, 396, 409 citronella, 57, 150, 388, 409, 430 fruit, 397 cloves, 417, 419 clove stems, 417 cones of Abies alba, 34, 72 copaiba balsam, 417 INDEX. 451 Oil of coriander, 35, 383 coto bark, para = Oil of paracoto bark, 414 cubeb, 87, 414, 424 curcuma, 108 dill, 71, 108, 178 elderberry, 35, 415 elemi, 108 erigeron, 71, 257 canadensis, 258 eucalyptus, 323, 324 amygdalina, 108 backhousia citriodora, 397 camphora, 286 eloeophora, 286 globulus, 34, 170, 266, 324 goniocalyx, 286 macarthuri, 388 macrorrhyucha, 386 maculata, 409 var. citriodora, 388, 409 piperita, 285, 286 smithii, 286 stricta, 286 staigeriana, 397 European pennyroyal (Mentha pule- gium), 237 fennel, 35, 87, 155, 156 feverfew, 133 fleabane = Oil of erigeron, 71, 257 frankincense = Oil of olibanum, 34, 87, 108, 414: galangel, 323 galbanum, 35, 414 geranium, African = Oil of pelargo- nium, 388, 394, 395 Bourbon, 307 Indian = Oil of palmarosa, 388, 394, 395 rose = Oil of pelargonium, 388, 394, 395 Turkish = Oil of palmarosa, 388, 394, 395 ginger, 57, 108, 429 golden rod, 87, 108, 142, 415 fuaiac wood, 426 emlock needle, 34, 57, 142 hops, 380, 421 iva, 324 juniper berries, 34, 415 kesso = Oil of valerian root, Jap- anese, 35, 57, 257 kesso-root, 35, 87 kuromoji, 71, 87, 178, 257 Labrador tea, 425 laurel berries, 34, 323 leaves, 34, 323 lavender, 35, 324, 381, 382, 387, 388 lavender, spike = Oil of spike, 35, 57, 142, 324, 381, 388 ledum palustre = Oil of Labrador tea 425 lemon, 34, 57, 71, 108, 381, 396, 409 grass, 388, 397, 405 Levant wormseed, 323, 324 limes = Oil of limetta leaf, 87, 381, 382, 397 limetta leaf, 87, 381, 382, 397 linaloe, 381, 382, 388 1 Oil of lovage, 266 mace, 34, 87 mandarin, 397 marjoram = Oil of sweet marjoram, 112 257, 267 marsh tea = Oil of Labrador tea, 425 massoy bark, 35, 71, 87 Matricaria parthenium = Oil of fever- few, 133 melissa =■ Oil of balm, 397 Mentha crispa, 185 pulegium = Oil of European pen- nyroyal, 237 myrcia = Oil of bay, 35, 108, 377, 397 myrtle, 35, 87, 324 neroli = Oil of orange flowers, 381, 388 niaouli, 35, 267 nutmeg, 35, 87 olibanum, 34, 87, 108, 414 orange flowers, 381, 386 peel, 71, 397 _ sweet, 71 Origanum majorana = Oil of sweet marjoram, 112, 257, 267 Smyrna, 380, 381, 382 palmarosa = Oil of East Indian gera- nium, 388, 394, 395 paracoto bark, 414 parsley, 35 patchouly, 414, 425 pelargonium, 388, 394, 395 pennyroyal, 237 American, 237 European, 237 Spanish, 238 pepper, Florida, 87, 108, 415 Japanese, 87, 108, 397 peppermint, 35, 72, 108, 127, 295, 308, 324, 415 American, 295 Russian, 285 petitgrain, 381, 388 pimenta, 397 pine needle, 142 from Abies alba, 34, 72, 142 siberica, 142 Picea excelsa, 34, 87, 108, 142, 414 nigra, 142 Pinus montana, 34, 99, 108, 142, 414 silvestris, 34, 99, 414 resin, 34 Pinus sibirica, 57 poplar buds, 422 pulegioides Persoon, 237 resin, 35 rose, 394, 395, 410 German, 388 Turkish, 388 rosemary, 35, 57, 142 323 sage, salvia officinalis, 34, 142, 224, 323, 381 sclarea, 142, 224, 323, 381 salviol = Oil of sage, 224, 323 sandalwood, East Indian, 426, 427 "West Indian, 428 sassafras bark, 35, 108 452 INDEX. Oil of sassafras leaves, 35, 108, 377, 381, 387, 388, 397 satureja, 142 savin, 121, 204, 414 spearmint, American, 35, 72, 178 German, 35, 178 Russian, 35, 72, 178, 324, 381 spike = Oil of lavender, spike, 35, 57 142, 324, 381, 388 star anise = Oil of anise, star, 35, 108 sweet marjoram, 112, 257, 267 tansy, 35, 224, 225 thuja, 35, 155, 156, 224, 236, 237 thyme, 35, 87, 142, 381 turpentine, American, 34, 57, 320,431, 432 French, 34, 266,431, 434 German, 34 Russian, 34, 87, 99 Swedish, 34, 87, 99 valerian, 34, 142 Japanese = Oil of kesso, 35, 57, 257 verhena, 397 water fennel, 35, 108 wormseed, American, 87, 432 Levant =Oil of Levant wormseed, 323, 324 wormwood, 87, 108, 225, 415 ylang-ylang (Cananga odorata), 381, 388, 415 zedoary, 324 Olefinic alcohols, 381 aldehydes, 396 amines, 413 camphors, 28 hydrocarbons, 377 sesquiterpene from the oil of citro- nella, 430 terpene in the oil of hops, 330 origanum, 380 terpenes, 28, 377 Olibanum, 35 Olibene. 34 Ortho-diketone, C10H16O2, 309 isopulegol, 247 isopulegone, 246 terpenes, 84, 120 Oxalic acid, 158, 212, 222, 224, 277, 392 Oxide, C9H16O2, 233 C9H16O2, bromide of, 233 Oxy-acid, CaHuOs, 274 Oxy-acid, CioHieOs, 403 a-amyrin, 433 a-amyrin acetate, 433 o-Oxy-benzylidene fenchylamine, 351 ^J-Oxy-benzylidene fenchylamine, 351 0- Oxy-benzylidene rf-menthylamine, 372 Z-menthylamine, 369 pinylamine, 338 1- 8-Oxybromotetrahydrocarvone, 209, 221, 267, 291 Oxycamphene = Carvenone, 62 Oxy-camphenilanic acid, 65 camphoceonic acid lactone, 64 camphor, 136 carbofenchone=Carbofenchonone, 169 dioxime, 169 Oxy-oxime, 169 carone, 209, 221, 291 keto-terpine from, 221 oxime, 221 phenylhydrazone, 221 semicarbazone, 221 oxime, 221 phenylurethane, 221 semicarbazone, 221 Oxydihydrocarvone, 211, 277 semicarbazone, 211 Oxydihydrocarvoxime, 211, 262, 277 diacetyl derivative of, 211 Oxydihydrofencholenamide, 167 Oxydihydrofencholenic acid, 168 lactone, 168 Oxydihydrofencholenonitrile, 167 a-Oxydimethyltricarballylic acid, 55 lactone, 55 D-d-Oxyfenchenic acid, 70 acetyl derivative of, 70 ZM-Oxyfenchenic acid, 69 ZM-Oxyfenchenic acid, acetyl derivative of, 69 i-d-Oxyfenchenic acid, 70 Oxyfenchenic acid, racemic, 70 Oxygenated compound, C10H16O, 337 Oxy-2-hexahydro-p-cyniene, 237 homopinic acid, 55 hydromenthonylamine, 303, 393, 413 isocamphoronic acid, 52 a-Oxy-isocamphoronic acid lactone, 55 a-Oxy-isopropyl-AY-hexenoic acid, 332 Oxy-ketone, 274 semicarbazone, 274 menthylic acid, 129, 299, 810 derivatives of, 310 oxime, 304, 310 methylene camphor, 140 methylene carvone, 194 methylene menthone, 305 derivatives of, 305 Oxymethylene tetrahydrocarvone, 221, 290 thujone, 229 a-Oxy-a 1 -methyl-a-isopropyl-adipic acid 1 218 Oxy-oxime, CioHis(OH)NOH, 181 S-Oxy-a-oxyisopropyl hexenoic acid, 332 Oxypinic acid, 56 Oxyterpenylic acid, 84, 196 dilactone, 84, 196 Oxytetrahydrocarvone, 214, 220 semicarbazone, 214 cymenes, 20, 21 Oxytrimethylsuccinic acid, 52 P Palmityl-/3-amyrin, 434 Paracajeputene, 432 Parapulegone, 246 Paratoluic acid, 215, 274 Paraxylic acid, 158 Patchoulene, 425 Patchouly alcohol, 425 camphor, 425 y-Pentylene glycol, 331 oxide, 331 INDEX. 453 Peppermint camphor, 308 Pernitrosocamphenone, 153 dibromide = Dibromopernitroso camphor, 153 Pernitrosocamphor, 153, 251 fenchone, 166 menthone, 304 thujone, 228 Phellandrene, 108, 377 diamine, 110, 375 dibromide, 109 nitrosite, 109, 364, 375 Phenyl bornylcarbamide, 342 dihydrocarvylurethane, 213 Phenylurethane, C17H23OSN, 129 Picean-ring, 56 Pimelic acid, 230 0-Pimelic acid, 310 Pinacone, C20H34O2, 170 Pinacoline, 329 Pinarin, 56 Pinene, 34 action of hypochlorous acid on, 40 of nitrous acid on, 41, 202 formaldehyde derivative of, 41 acetate, 41 benzoate, 41 dihydrobromide, 41 dihydrochloride, 41 behavior towards bromine, 44 dibromide, liquid, 45 solid, 45 dichloride, 46 glycol, 46, 152 hydriodide, 40 hydrobromide, 39 hydrochloride, 38 nitrolallylamine, 42 amines, 42 amylamine, 42 benzylamine, 43 piperidide, 42 propylamine, 42 nitrosobromide, 42 chloride, 41 oxidation of, 46 phthalimide, 339 phthalamic acid, 339 picrate, 38 Pinenol, 202 acetate, 202 dibromide, 202 Pinenone, 203 dibromide, 203 semicarbazone, 203 Pinenonoxime, 203 benzoyl derivative of, 203 butyryl derivative of, 203 dibromide, 203 phenylcarbimide, 203 . Pine wood, 35, 87, 99 Pinic acid, 53, 56 Pinocampholenamide, 155 Pinocampholenic acids, 50, 155 Pinocampholenonitrile, 154 Pinocampheol, 155 Pinocamphone, 154 oxime, 154 semicarbazone, 155 Pinocaniphonitrile, 154 Pinocamphylamine, 154 acetyl derivative of, 154 Pinocamphyl carbamide, 154 phenylurethane, 155 Pinocarveol, 201, 202, 338 Pinocarvone, 201 acid sodium sulphite derivative of, 201 hydrogen sulphide, 201 oxime, 201 semicarbazone, 202 i-Pinodihydrocampholenolactone, 50 Pinole, 42, 47, 260, 274 bisnitrosochloride, 283 benzoyl derivative of, 284 ethoxyl derivative of, 284 methoxyl derivative of, 284 cis-Pinole dibromide, 278 Pinole glycols, 334 cis-Pinole glycol, 279 cis-trans-Pinole glycol, 279 eZ-cis-trans-Pinole glycol, 280, 282 cis-Pinole glycol, anhydride of, 278, 280 1- chlorhydrin, 281 2- chlorhydrin, 40, 281 diacetate, 280 diethyl ether, 280 dipropionate, 280 hydrate, 260, 276, 334 diacetate, 277 cis-Pinole hydrate dibromide, 277 Pinole hydrate, oxidation of, 277 hydrobromide, 276 isonitrosochloride, 283 nitrolainine, 284 hydrochloride, 284 amines, 284 anilide, 285 benzylamine, 285 j3-naphthylamine, 285 piperidide, 284 nitrosochlorides, 283 oxidation of, 285, '279 cis-Pinole oxide (Wallach's anhydride of cis-pinole glycol), 40, 280 tetrabromide, 279 tribromide, 253, 278 Pinolic acids, 49 Pinolol, 253 Pinolone, 253, 279 Pinol on oxime, 253 amine from, 253 carbamide of, 253 semicarbazone, 253 Pinonic acids, 48, 49, 53 derivatives of, 48, 49 keto-lactones from, 48, 49 oximes of, 48, 49, 53 phenylhydrazones of, 53 semicarbazones of, 48, 49 Pinononic acid, 47 oxime, 47 Pinoylformic acid, 54 derivative of, 54 phenylhydrazone, 54 Pinylamine, 154, 202, 836 acetyl derivative of, 337 benzoyl derivative of, 338 454 INDEX. Pinylamine, benzylidene derivative of, 338 furfuro-derivative of, 338 hydrochloride, 337 nitrate, 201, 202, 336, 337 oxalate, 337 o-oxybenzylidene derivative of, 338 picrate, 337 platinochloride, 337 sulphate, 337 thiocyanate, 337 Pinylcarbamide, 338 Polyterpenes, 17, 414, 431, 432 Propionyl fenchylamine, 349 d-Propionyl menthylamine, 371 Z-Propionyl menthylamine, 369 Pseudoionone, 407 pulegone, 246 Pseudo-terpene alcohol, 205 Pseudo-terpenes, 84, 114, 121 Pulegenacetone, 243 benzoyl derivative of, 243 oxime, 243 Pulegenic acid, 245 amide, 245 bromo-lactone from, 246 ketone from, 246 methyl ester, 245 hydrochloride of, 245 oxime, 246 oxy-acid from, 246 oxy-lactone from, 246 Pulegenolide, 246 Pulegenonitrile, 245 Pulegonamine, 241, 363 benzoyl derivative of, 363 hydrochloric acid derivative of, 363 methyl derivative of, 363 phenylthiocarbamide, 363 Pulegondioxime hydrate, 242 Pulegone, 237, 364 acid sodium sulphite derivative of, 238 benzylidene derivative of, 342 bisnitroso-derivative of, 242 derivatives, table of, 250 dibromide, 245 dinitrosylic acid, 242 hydrobromide, 239 oxime of, 239 hydrochloride, 238 hydroxylamine, 240, 241 nitroso-amine of, 241 oxalate, 241 inactive, 239 isonitroso-derivative of, 242 methylamine, 363 oxidation of, 243 semicarbazone, 242 Pulegonoxime, C10H19NO2, hydrated (Beckmann and Pleissner's oxime) = Pulegone hydroxylamine, 240 hydrated, acetyl derivative of, 241 benzoyl derivative of, 241 hydrochloride, 241 CioHieNOH, normal, 240 hydrobromide, 239 Pulegylamine, 240, 362 hydrochloride, 363 oxalate, 362 Pulegyl carbamine, 363 phenylcarbamide, 363 Pyruvic acid, 237 Q Quinone from thujone tribromide, 227 R ßacemic-a-carvylamine, 356 ß-carvylamine, 356 Reduction products of carvone, 194 Reuniol, 389, 394, 395 Rhodinal =Geranial, 388 Rhodinol = Geraniol, 388, 389, 394 Rhodinolic acid = Geranie acid, 406 Roseol, 388, 389, 394 S Sabinene, 121 dibromide, 121 glycol, 121 ketone, 122 semicarbazone, 122 Sabinenic acid, 122 Sabinol, 204 acetate, 204, 205 addition-products of, 205 Sabinyl glycerol, 205 Sal viol = Thujone, 225 Santalal, 427 semicarbazone, 427 a-Santalene, 427 acetate, 427 dihydrochloride, 427 nitrolpiperidide, 427 nitrosochloride, 427 /3-Santalene, 427 acetate, 427 dihydrochloride, 427 nitrolpiperidides, 427 nitrosochlorides, 427 Santalic acid, 427 a-Santalol, 426, 428 acetate, 426 |3-Santalol, 426, 428 acetate, 426 Sesquiterpene alcohol, 427 alcohols, 414 Sesquiterpenes, 17, 4H classification of, 430 Silver cineolate, 327 a-fencholenate, 164 Sobrerol = Pinole hydrate, 276 Sobrerone = Pinole, 276 cis-Sobrerytrite (menthane-1, 2, 6, 8-tetrol) _ = cis-Sobrerythritol, 40, 282 cis-trans-Sobrerythrite (menthane-1, 2,6,8- tetrol) = eis - trans - Sobrerythritol, 277 hydrate, 277 cis-Sobrerythritol, 40, 282 cis-trans-Sobrerythritol, 277 Sodium carvone dihydrodisulphonate, 193 semicarbazone, 193 a-fencholenate, 164 geranial hydrosulphonate, 398 semicarbazone dihydrodisulpho- nate, 398 linaloolate, 384, 387 INDEX. 455 Sodium mentholate, 310 menthylxanthate, 312 Stable camphol = Borneol, 146 Succinic acid, 64, 253 Sylvestrene, 99 dihydriodide, 102 dihydrobronride, 101 dihydrochioride, 99, 101 nitrolbenzylamine, 102 nitrosochloride, 102 reaction, 101, 103, 104 tetrabromide, 102 Symmetrical menthol, 315 cis-Symmetrical menthol, 315 derivative of, 316 menthone = 1, 3-methyl isopropyl cy- clohexanone-5, 308 derivative of, 308 Synthetical isoborneol = Fenchylalcohol, 171 pulegol, 247 pulegone = Ortho-iso(?)-pulegone, 246 benzylidene derivative of, 247 compound, C13H20O, from, 247 derivatives, table of, 250 semicarbazone, 247 terpene, 120, 247 T Table, Borneol and isoborneol, and their derivatives, 149 Carvoxime and its derivatives, 187 Derivatives of bornylamine( Forster), neobornylamine (Forster) and bor- nylamine (Leuckart, Wallach), 345 Fenchyl alcohol and isofenchyl alco- hol, and their derivatives, 175 Isomerism in the limonene series, 78 Limonene and dipentene derivatives, relations to oxidized compounds of the terpene series, 100 Limonene nitrosochloride and com- pounds derived from it, 186 Properties of a- and /3-amyrin and derivatives, 434 Properties of bornyl esters, 143 Properties of linalool from different oils, 382 Pulegone, isopulegone, synthetical or ortho-isopulegone and deriva- tives, 250 Belation of terpineol (m. p. 35°) to other terpene derivatives, 268 Botatory powers of the limonene de- rivatives, 86 Specific and molecular rotatory powers of fenchylamine and deriva- tives, 351 Specific and molecular rotatory pow- ers of rf-and Z-menthylamines and derivaties, 373 Specific rotatory powers of carvone and its derivatives, 197 Transformations in the terpene series, 122 Transformations of the keto- and oxy- hydrocymenes, 335 Tanacetene = Thujene, 118, 360 a-Tanacetogendicarboxylic acid, 205, 229, 230 anhydride, 230 ß-Tanacetogendicarboxylic acid, 230 Tanacetogen dioxide, 233 Tanacetogenic acid, 234 Tanacetoketocarboxylic acids, 229 Tanacetoketone = Thujaketone, 232 Tanacetoketoximic acids, 231 Tanacetone = Thujone, 224 Tanacetophorone, 230 Tanacetyl alcohol = Thujyl alcohol, 234 amine = Thujyl amine, 227, 360 chloride = Thujyl chloride, 235 Terebentene, 34 Terebic acid, 51, 222, 264, 277, 406 Terephthalic acid, 64 Teresantalic acid, 428 Terpadienes, 23 Terpane = Cineole, 324 = Hexahydrocymene, 23, 130 Terpanes, 130 Terpan-2-ol — Carvomenthol, 291 3-ol = Menthol, 308 Terpanols, 23 Terpan-2-one = Carvomenthone, 287 -3-one = Menthone, 295 Terpanones, 23 Terpan-1, 4, 8-triol = Trioxyterpane, 334 A 1 -Terpene = Carvomenthene, 124 A 3 -Terpene = Menthene, 126 Terpene from the resin of Indian hemp, 119 hydrochloride of, 119 Terpenes proper, 17, 34 transformations of, 122 Ai-Terpen-S-ol, 189, 256 A^Terpen^-ol, 256, 261 A«(9)-Terpen-l-ol, 256, 273 derivatives of, 274 A*(8) -Terpen-l-ol, 93, 105, 269 acetate, 93, 106, 269 dibromide, 93, 270 nitrosobromide, 270 nitrosochloride, 270 dibromide, 270 nitrososochloride, 270 oxidation of, 273 Terpenols, 23 Terpenone, 237, 289 semicarbazone, 289 Terpenones, 23 Terpenylic acid, 196, 264, 267, 277 Terpilene = Terpinene, 58, 85, 112 Terpilenol = Terpineol, 258 Terpine, 318 cis-Terpine, 320 trans-Terpine, 319 Terpine acetate, 322 hydrate, 254, 320, 432 oxidation of, 322, 323 mono-acetyl ester, 322 methyl-, 318 acetate of, 318 oxidation of, 319 Terpinene, 112, 213, 357 benzoyl isonitrosite, 116 dibromide, 114 nitrolamine, 117 456 INDEX. Terpinene nitrolamine, dibenzoyl deriva- tive of, 117 nitrolamines, 116 amylamine, 118 benzylarnine, 118 diethylamine, 118 dimethylamine, 117 ethylamine, 118 nitroso-derivative of, 118 methylamine, 117 prperidide, 118 nitrosite, 114 oxide oxime, 115 isomeride of, 115 Terpineol, 254 isomeric, m.p. 32° to 33°, 273 nitrolpiperidide, 274 nitrosochloride, 274 phenylurethane, 274 isomeric, m.p. 69° to 70° = A«8).Ter- pen-l-ol, 269 " Terpineol," liquid, 254, 257, 258 dibromide, 257 Terpineols, 254, 266, 267 Terpineol, solid, m.p. 35°, 255, 258 dibromide, 198, 260 keto-lactone from, 263 nitrolamines, 262 anilide, 262 piperidide, 262, 266 nitrosate, 262 nitrosochloride, 261, 266 oxidation of, 262 relation to other terpene derivatives, table of, 268 Terpines, 319 Terpinolene, 105 dibromide, 107 tetrabromide, 107 Terpinyl acetate, 259 formate, 258, 259, 266 methyl ether, 259 phenylurethane, 259, 266 Tertiary carvomenthol, 316 carvomenthylamine, 373 derivatives of, 374 carvomenthyl bromide, 317, 373 carvomenthyl iodide, 816, 373 menthol, 317 menthylamine, 374 derivatives of, 374 menthyl acetate, 317 bromide, 317, 374 iodide, 817, 374 methyl ether, 260; 317 phenylthiocarbamide, 374 Tetrabromide, CioHuBu, 93 Tetrabromogeranyl phthalate, 393 Tetrahydric alcohol, C10H20O4, 363 Tetrahydrocarveol, 111, 214, 217, 237, 291 acetate, 214, 298 bromide and chloride, 293 derivatives of, 293 Tetrahydrocarvone, 111, 287 acid sodium sulphite, 288 bisnitrosylic acid, 288 oxime, 288 condensation-product with benzalde- hyde, 290 Tetrahydrocarvone, oxidation of, 288 oxymethylene compound of, 221, 290 semicarbazones, 290 Tetrahydrocarvotanacetone = Tetrahydro carveol, 292 Tetrahydrocarvoxime, 289 Tetrahydrocarvyl acetate, 214, 298 amine=Carvomenthylamine, 111, 290, 868 bromide, 293 chloride, 293 phenylurethane, 293 Tetrahydrochlorocymene, 293 Tetrahydrocymene, 18 Tetrahy drocymene = Carvomenthene, 124 [ Tetrahydrocymene = Menthene, 126 Tetrahydroeucarvone, 223, 293 oxime, 293 oxidation of, 294 semicarbazone, 293 Tetrahydrofenchene, 181, 159 bromo-derivative of, 131 Tetrahydroisocamphor, 252 phenylurethane, 252 Tetrahydropinene, 39, ISO Tetraterebentene, 435 dihydrobromide, 435 dihydrochloride, 435 hydrochloride, 435 Tetraterpenes, 435 Thujaketone, 232 oxime, 232 a-Thujaketonic acid, 229 ß-Thujaketonic acid, 229 a-Thujaketoximic acid, 157, 281 hydrobromide, 231 hydrochloride, 231 ß-Thujaketoximic acid, 157, 281 Thujamenthol, 236, 295 Thujamenthone, 236, 294 keto-lactone from, 295 oxidation of, 295 oxime, 294 semicarbazone, 294 Thujene, 118, 205, 235, 360, 361, 362 Thujolacetic acid, 227 ethyl ester, 227 Thujone, 157, 205, 224 acid sodium sulphite, 225 ethoxyl-derivative of, 227 methoxyl-derivative of, 226 oxidation of, 229, 233 oxime, 227 isomeride of, 227 oxymethylene derivative of, 229 pernitroso-derivative of, 228 semicarbazone, 228 tribromide, 226 acetyl derivative of, 227 Thujylamine, 227, 360, 362 carbamate, 360 hydrochloride, 360 isomeric, 361 hydrochloride, 361 nitrate, 361 phenylcarbamide, 361 Thujyl alcohol, 205, 227, 234 chloride, 235 Thujylimine nitrate, 228 INDEX. 457 Thujyl phenylcarbamide, 361 isomeric, 361 trimethyl ammonium hydroxide, 361 iodide, 361 Thymoquinone, 189 jj-Toluic acid, 215 Tribromocamphene, 62 hydrobromides, 61, 62 Tribromofenchone, 159 heptanonol, 406 methyl hexyl carbinol, 406 1, 2, 4-Tribromoterpane, 198, 260 1, 2, 8-Tribromoterpane, 198 1, 4, 8-Tribromoterpane, see monobro- modipentene dihydrobromide, 92, 198 Tricyclene, 46, 121 dichloride, 41, 46 hydrochloride, 121 Tricyclenes, 64 Trimethylamine, 31, 370 2, 3, 5-Trimethylamine pyrrolidine, 31 Trimethyl terebentyl ammonium chlor- ide, 340 iodide, 340 Trioxyhexahydrocymene, 208, 214, 234, 262, 266 Trioxyhexahydrocymene, derivatives of, 1, 2, 8-Trioxymenthane = 1, 2, 8-Trioxy- terpane, 262, 266 1, 2, 8-Trioxyterpane, 221, 262 1, 4, 8-Trioxyterpane, 273, 334 Triterpenes, 432 V Valerian camphor, 142 v-Valerolactone-y-acetic acid, 243 Valerylene, polymerization of, 431 Vestrylamine, 359 hydrochloride, 103, 359 Ylang-ylang essence = Oil of ylang-ylang 381, 388, 415 Z Zingiberene, 429 dihydrochloride, 429 nitrosate, 430 nitrosite, 429 nitrosochloride, 429 tetrabromide, 430