Pi dee )t 2 FOTO ean ANGIE ‘ ae ‘i as eye ( 3 * oe “ a a emer EO ti LTE RESEARCH LIBRARY Piemarehy RESEARCH INSTITUTE JOHN MOORE ANDREAS COLOR CHEMISTRY LIBRARY FOUNDATION ter = A LABORATORY OUTLINE OF ORGANIC CHEMISTRY BY LAUDER WILLIAM JONES PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF CINCINNATI NEW YORK THE CENTURY CO. 1911 . Copyright, 1911, by i, aunty ae PREFACE. TEXT-BOOKS which treat of the experimental aspect of organic chemistry are already so abundant that the issuing of a new book of this kind would seem to demand some very convincing apology on the part of the author. The major part of the material included in this book has formed the subject matter of a number of distinct courses which I conducted in the University of Chicago during the years 1897- 1907. ‘These courses were planned for large classes, and were - arranged to meet the needs of students with diversified interests in chemistry. The classes included students in the College of Liberal Arts and in the School of Science; premedical students and medical students; students somewhat more advanced who came for summer courses; and graduate students. Since 1907 the same outlines have been in use at the University of Cin- cinnati, and have been made to include certain phases of the subject particularly suited to students of chemical engineering. Mimeographed sheets were employed, and were revised each year so as to include precautions and changes which actual experience in teaching suggested as desirable to make the direc- tions as free as possible from the ambiguity so difficult to avoid in description of this kind. From this brief history it will be apparent that the present selection of problems has been determined by the need of meeting educational demands both varied and complicated. Within the past few years the science of chemistry has pressed over its boundaries far into neutral territory, where with other sciences, — once almost alien, — it has met for the purpose of forming a closer alliance which augurs great mutual benefit to all. As a result of this increased cooperation, it has come about that students engaged in the study of those sciences which border closely upon chemistry, can no longer rest content to follow the old-time practice of acquiring a knowledge of chemistry through lll iv PREFACE a brief, and frequently unprofitable period of dabbling in an elementary laboratory; or through listening impatiently to a few meager lectures designed for a special clan of workers, and arranged with the avowed purpose of giving the least possible amount of chemistry with the least expenditure of time. In most institutions of learning there has grown up an in- creasing demand for more intensive as well as extensive training in elementary chemistry; and this has brought about corre- sponding changes in the curriculum of chemistry. Experimental organic chemistry, once a mature part of the course, usually | preceded by qualitative and quantitative analysis, and requiring a reading knowledge of German and French, now finds itself stranded with general inorganic chemistry as its sole prerequisite. The majority of laboratory outlines of organic chemistry, although for the most part excellent, are designed primarily for the mature student in chemistry who is able to read and to digest the original articles cited for reference; and for those who are concerned more especially with varied manipulation and method rather than with a systematic survey of the salient facts and relations underlying the science. On the other hand, the few briefer and simpler outlines extant can hardly be regarded as adequate to give the kind of preparatory training which is now being sought in many quarters. It would seem, therefore, that there is a place for a text-book which shall approach the subject matter of organic chemistry in much the same thorough but elementary fashion that we are wont to employ in laboratory manuals of inorganic chemistry. In other words, there is need of a course in GENERAL ORGANIC CHEMISTRY. It is hoped that this book may occupy a position and supply a demand of this character. From what has been said already concerning the origin of this outline, it will be self-evident that it is not intended that any one student shall perform all the experiments given on the follow- ing pages. On the contrary, it has been my practice to choose certain limited sets of experiments to meet the needs of par- ticular classes; and, in some cases, to assign different lists of experiments to different students of the same class. The re- quirements of each case must decide what choice shall be made. The experiments have been arranged to follow approximately the usual order of subject matter given in most text-books, and PREFACE Vv in most courses of lectures. However, the sections and chapters have been grouped and numbered in such a way that by properly chosen assignments other arrangements are easily possible. Thus, the aliphatic and aromatic compounds of the same class — e.g., hydrocarbons, halogen derivatives, alcohols and phenols — might be considered side by side. Similar processes, such as oxidation, reduction, esterification, condensation, might be grouped together for comparative study. Other similar selections will suggest themselves. Many of the experiments have been used for lecture demonstration. .The questions which are appended to each section are by no means intended to exhaust the possibilities in that direction. They are merely a few questions which I have found to be valu- able in arousing students to assume an inquiring attitude towards the work. Explanations of the processes, descriptive matter to elucidate reactions, and equations have been omitted advisedly. It is to be presumed that upon a shelf in the laboratory there will be a number of the best reference works on organic chemistry to which the student may be sent for such descriptive matter. In conclusion, I wish to acknowledge my indebtedness to the many excellent texts on organic chemistry by Emil Fischer, Ludwig Gattermann, F. W. Henle, W. A. Noyes, Julius Cohen, and others. Very many suggestions have been taken from the comprehensive work by 8. P. Mulliken entitled ‘The Identifi- cation of Pure Organic Compounds.’ I wish to express my obligations to Dr. Martin Fischer, head of the Department of Physiology in the University of Cincinnati, for the chapter on col- loids. The drawings for the illustrations were made by Mr.. Howard A. Dorsey, whom I wish to thank for the personal inter- est which he took in making them. There must be other debts which I owe and would gladly proclaim at this time; but, at the close of the slow process of accretion by which a collection of this _ kind is shaped to appear in published form, the various elements ' become so interwoven that the actual sources of many details cease to be clearly defined in the thought of the author. LAUDER WILLIAM JONES. UNIVERSITY OF CINCINNATI, February 21, 1911. DIvISsION Ir: II. III. IV: NV; VI. VII. VIII. IX. DIvISION te ai XII. LIL. XIV. XV. XVI. VIE XVIII. Division DeLX. XX. XXI. CONTENTS DIRECTIONS FOR THE LABORATORY . . PART I. THE ALIPHATIC SERIES. 1. Tue Monatomic ComMPpounDs FRACTIONAL DISTILLATION AND THE Paneae on or ABSOLUTE ALCOHOL . tee teacne-PAnavrrnn, OunriNs, AND hee YLENE .. HALOGEN See Swe ere Monatomic ALCOHOLS AND ETHERS ALDEHYDES AND KETONES . Monosasic Farry Acips DERIVATIVES OF Farry Acips . SULPHUR COMPOUNDS . : CoMPouNDS CONTAINING Sean C7 6 ue ah oe 2. PoutyatTomic COMPOUNDS . HALOGEN COMPOUNDS . ; Potyatomic ALCOHOLS AND Drees Disasic AcIDS . CYANOGEN AND eee (ore NDE UREA AND THE UREIDS i PoLtyaToMic COMPOUNDS WITH Mise Eanertone CARBOHYDRATES Amino AcIDsS . CoLLOoIps PART II. THE AROMATIC SERIES. 1. CarsBocyctic CoMPOUNDS BENZENE HyDROCARBONS : NITROBENZENE AND SOME OF ITs REDUCTION Pear UcTS ; DIAZONIUM ae AND D1Azo Coane DyzEs rhsee Vii PAGE 89 95 Vill XXII. XXII. XXIV. XXYV. XXVI. XXVII. XXVIII. XXIX. CONTENTS PHENYLHYDRAZINE. NITROSAMINES. NiITROSO- PHENOL. DIPHENYLAMINE Dyess PHENOLS AND SOME RELATED COMPOUNDS. ALDEHYDES AND KETONES . i: Aromatic Acips AND THEIR Duarastoee : DERIVATIVES OF DIPHENYLMETHANE AND OF Dt- PHENYLETHANE : ; DERIVATIVES OF TRiruhyyianeeeee von Tareas YLMETHANE Dysgs . EXPERIMENTS IN DyYBING q NAPHTHALENE AND ANTHRACENE . Division 2. HeEtTEROcycLIc CoMPOUNDS XXX. XXXII. HETEROCYCLIC COMPOUNDS: — Murivro Bee eee PYRAZOLON; INDIGO; PYRIDINE; QUINOLINE METALLO-ORGANIC COMPOUNDS . APPENDICES. APPENDIX A. TEMPERATURE MEASUREMENT AND HEAT Units. Herat VALUE APPENDIX B. PrRrEssuRE MEASUREMENT ia APPENDIX C. VoLUME AND WEIGHT Re ee SPECIFIC GRAVITY ApprenpIx D. DIsSsocIATION Conahintaal OF - Onaae Aeues AND BASES . ApprenpDIx FE. HybDROLYSIS OF Spe OF Winns: Aaa AND oF WEAK BASES APPENDIX F. Lists or APPARATUS Newoee TO Paepoan THE EXPERIMENTS IN THIS OUTLINE APPENDIX G. Some SPECIAL APPARATUS FOR Panam REAGENTS. APPENDIX H. Lists oF Gasss, Tague AND Sousa USED AS REAGENTS FOR ORGANIC CHEMISTRY : APPENDIX I. ReAGENT BoTTLES AND REAGENT SHELVES . 134 137 142 143 149 155 156 159 164 173 DIRECTIONS FOR THE LABORATORY General Directions. I. Provide yourself with a note-book. A record of each experiment and answers to all the questions should be put in the note-book. In all equations use the constitutional formule, not the empirical formule. An equation, however, will not be sufficient; it should be accompanied by a brief account of the process, not a mere copy of the directions, but a statement of the reasons for the various steps in the operation. If desired, a rough sketch of the apparatus may be put in also. II. In the case of a few long experiments, two students may work together. These experiments are marked “ For two Stu- dents.”” In all other preparations, the work must be entirely independent. III. It is the object of the actual preparation to obtain pure compounds. Whenever it is possible, the degree of purity should always be ascertained by a determination of the melting- point or of the boiling-point of the finished product. Concerning Apparatus. IV. When the apparatus has been checked, clean it thor- oughly before putting it away in the desk. V. Prepare a water-bottle for distilled water. VI. Cut a glass rod into pieces 6 to 8 inches long, and round the rough ends of each piece by heating them in a flame. VII. See that you have two pieces of rubber tubing long enough to connect the condenser with the water supply. VIII. At all times, apparatus not actually in use, which tends to accumulate on the top of the desk, should be cleared away; a desk with plenty of working space will enable you to accomplish more work during a laboratory period. Concerning Weights and ‘‘ Yields.’’ IX. For all preparations, the prescribed amounts must be weighed on an ordinary chemical balance. Do not guess at the amounts. X. When the yield is called for at the close of an experiment, note the amount of pure product, and compare this with the 2 DIRECTIONS FOR THE LABORATORY amount theoretically obtainable. By the amount “ theoreti- cally obtainable” is meant the weight of the substance which would be obtained if the reaction proceeded completely in one direction according to the equation. Laboratory Precautions. XI. Whenever substances are used which have unpleasant odors or evolve injurious gases (e.g., ammonia, bromine, hydro- gen sulphide, hydrochloric acid, amyl alcohol, etc.), the opera- tion must be conducted under a hood. XII. Vessels or apparatus containing volatile materials to be heated, or in which gases or vapors are evolved, must not be closed air-tight. XIII. Inflammable liquids, such as ether, ligroine, benzene, etc., in quantities of more than a few cubic centimeters, must not be heated over a free flame, but in vessels immersed in appropriate baths (water, paraffine, etc.). When such liquids are to be removed by distillation, always employ a condenser. XIV. Do not put combustible substances in the jars pro- vided for solid waste materials. Abbreviations. XV. The following abbreviations will be used: — [R]. = Consult a reference book. [Instructions]. = Consult an instructor before you proceed with the experiment. (?) = An answer must be given before you continue the preparation. Record these answers in your note-book. {H]. = Hood. [S.R.] = Store Room. [S.S.] = Side Shelf. Ber. = Berichte der deutschen chemischen Gesellschaft. Ann. = Liebig’s Annalen. Am. Chem. J. = American Chemical Journal. J. Am. Chem. Soc. = Journal of the American Chemical Society. PART I. ALIPHATIC SERIES. DIVISION 1. MONATOMIC COMPOUNDS. DIVISION 2. POLYATOMIC COMPOUNDS. OUTLINE OF ORGANIC CHEMISTRY CHAPTER I. FRACTIONAL DISTILLATION AND THE PREPARATION OF ABSOLUTE - ALCOHOL. Wi e e * 1. Fractional Distillation: Separation of a Mixture of Ethyl Alcohol and Water. Make a mixture containing 100 c.c. of ethyl alcohol (95 per cent.) and 100 c.c. of distilled water. Is there any change in temperature when these two liquids are mixed? Is the total volume of this mixture exactly 200 c.c.? Measure its Fig. 1. volume when it has reached the temperature which the water and alcohol had before mixing. Will the mixture kindle when a flame is applied to it? Pour the dilute alcohol into a 500-c.c. flask fitted with a fractionating-column and a thermometer; and connect the column with a condenser. 5 6 FRACTIONAL DISTILLATION [§ 1 Heat a piece of glass tubing in the flame of a Bunsen burner. When the glass is thoroughly softened, remove it from the _ flame and draw it out slowly, to make a narrow tube 1 mm. in diameter. Cut this narrow tube into pieces about 5 inches long, and seal one end of each piece. Such tubes are called “ebullition tubes.”’ They are used to prevent the violent “bumping”? which frequently results because of the super- heating of liquids. Put one of these tubes, open end down, into the flask. : To serve as receivers for the distillate, select four clean, dry flasks (about 100 c.c.), and number them consecutively from 1 to 4. Place the distilling-flask over a wire gauze, and apply heat sufficient to cause the liquid to distill so rapidly that you can still count the drops easily as they fall from the end of the condenser. When the flame has been adjusted, see that it stands exactly under the center of the flask, but do not alter it or remove the burner during the remainder of the distillation. Collect successively four fractions which boil between the following temperatures: — I, from ¢,°-82° inclusive; II, from 82+°-89°; III, from 89°-96°; IV, from 96°-4,°. Measure each fraction in a graduated cylinder. In more exact separations, it is frequently desirable to collect fractions at intervals of three to five degrees. This is necessary if the substances have boiling-points very close together. As a rule, substances whose boiling-points lie far apart are much more easily separated. For mixtures which cannot be separated by fractional distilla- tion, consult reference books. The following scheme will illustrate the method of tabulating your results: — Fraction I II III IV Temperature...... t1°-82° 82°-89° 89°-96° 96°-t2° Volumecence see 67 c.c. 45 c.¢c. 25 ¢.¢. 57 ©¢.¢. Second Fractionation. To make a further separation, distill the four fractions one after the other. However, since no one of the fractions has the composition of the original mixtures, the liquids will not pass over completely at the previous tem- * he Poe ioe A emus Se. = § 1] FRACTIONAL DISTILLATION 7 peratures; the alcohol will pass over more rapidly from the solutions stronger in alcohol. As a consequence of this altered distribution, the two end fractions will grow in volume, while the two intermediate fractions will diminish. If this process is repeated several times, the intermediate fractions will soon become practically negligible. To make the second fractionation, clean the distilling flask and pour the first fraction (4°-82° inclusive) into it. Make the connections previously used, place the flame under the wire gauze, and collect the distillate in flask 1. When the tempera- ture just exceeds 82°, there will still be some liquid left in the distilling-flask. By removing the Bunsen burner, interrupt the boiling at this point,.add fraction II (824°-89°), drop in a new ebullition tube, and resume the distillation without changing the receiving flask. There will be a small amount which will distill before the temperature passes 82°. When the tempera- ture again exceeds 82°, stop the distillation once more, add fraction III (89°-96°), and proceed as before. Now add fraction IV (96°-#,°). Even in this case there may be a slight amount which will boil below 82°. During the treatment of this fraction, when the temperature has reached 82°, do not discontinue the boiling, but change the receiving flask, putting flask 2 in place of flask 1. When the temperature has reached 89°, begin to collect the distillate in flask 3; and at 96°, use flask 4. The following table will show how the re- sults should be recorded. Fraction I II Ill IV Temperature...... t1;°-82° 82°-89° 89°-96° 96°-#,° WOHINGs atcisci sl 94 c.c. 10 c.c. 19 c.c. 70 c.e. A third fractionation may be made in stages like those just described for the second. This will lead to a more thorough separation because of the altered composition brought about by the second fractionation. Furthermore, it will be evident that any single fraction, say fraction I (t°-82°), may be subjected to a similar process of fractionation by means of which its sep- aration into alcohol and water could be made more nearly com- 8 FRACTIONAL DISTILLATION [§ 2 plete.* Try to kindle a sample of fraction I. Does it burn now? Absolute Ethyl Alcohol. 2. A Test for Water in Alcohol. Put a little pure-white anhydrous copper sulphate in a dry test-tube, and add to it 5 c.c. of ordinary alcohol. Close the test-tube with a tight- fitting stopper, shake it, and allow it to stand for an hour. What change in the appearance of the copper sulphate do you notice? Explain your observation. The Preparation of Absolute Alcohol. Pour 300 c.c. of ordi- nary 95 per cent. alcohol into a 1-liter flask. When pieces of good quicklime have been added to the alcohol until they reach the | Fig. 2. surface of it, connect the flask with a reflux-condenser, and heat the flask in a water-bath for an hour. During this time the alcohol should boil gently. When the water-bath has been removed, and the alcohol has ceased to boil, take the apparatus apart, and adjust the con- denser in the usual position for distillation. A clean, dry filter- flask will be found to be the most convenient form of receiver. By means of a sound cork stopper, fasten the filter-flask to the lower end of the condenser, and connect the side tube of the filter-flask with a straight calcium chloride tube, completely * A mixture of ethyl alcohol and water containing 95.57 per cent. of alcohol has a minimum boiling-point, 78.15° (760 mm.), so that it is not possible by distillation alone to make a separation beyond this point. Pure alcohol boils at 78.3°. § 2] FRACTIONAL DISTILLATION 9 filled with porous calcium chloride. [Instructions]. Do not close this tube with a stopper. Why? After these connections have been made, place the flask once more in the water-bath, and apply heat enough to cause the alcohol to distill at such a rate that “bumping” is entirely avoided. Collect the first 10 c.c. of the distillate in a small Fig. 3. flask, and allow the remainder to flow into the filter-flask. Keep the absolute alcohol in a labeled bottle, well corked; it will be needed for later experiments. a. Is it possible to prepare alcohol absolutely free from water? Apply the test with copper sulphate to the “absolute alcohol” which you have just made. b. Why do you discard the first portion of the distillate? Do the 10 c.c. which you collected first affect anhydrous copper sulphate? c. Can you suggest any other reagents which might be em- ployed to remove water from alcohol? What objections would there be to the use of sulphuric acid? of calcium chloride? of phosphorus pentoxide? of phosphorus pentachloride? ([R]. CHAPTER II. THE ALIPHATIC HYDROCARBONS — PARAFFINES, OLEFINES, AND ACETYLENES. 3. Tests for Carbon and Hydrogen in Organic Substances. In many cases the presence of carbon in a compound may be determined by heating a portion of the substance. If a charring occurs, or if gases are evolved which burn with a smoky flame, carbon is present. Black oxides or finely divided metals, which may be formed by the ignition of certain inorganic salts, must not be mistaken for carbon. a. Ignite a small quantity of sugar in a porcelain dish. Re- peat the experiment, using benzoic acid instead of sugar. b. Dry 3 or 4 grams of powdered copper oxide by heating it to redness for a few minutes in a small porcelain dish. After sealing one end of a glass tube 4-5 inches long, mix a little benzoic acid with some dry copper oxide; place the mixture at the bottom of the tube, and fill half of the remaining space with dry copper oxide. To permit the carbon dioxide and water vapor to escape freely, hold the tube in a horizontal position, and tap it on the desk so as to form a narrow channel between the oxide layer and the upper wall of the tube. First heat the upper layer of oxide, and then the lower layer containing ben- zoic acid. Prove that carbon dioxide is evolved. Is there any evidence of the formation of water? A. Sertes of Paraffine Hydrocarbons. 4. Methane: Its Preparation from Chloroform. Put 10 g. of “zinc dust” into a small flask, and cover the powder with dilute alcohol (1 part of water to 5 parts of alcohol). Fur- nish the flask with a stopper and a delivery-tube, so arranged that any gas evolved may be collected in test-tubes over water. Then add to the flask about 5 c.c. of chloroform and 1 c.c. of copper sulphate solution. The action will commence in the 10 le ete Ws Sac oy ? “Ty - tay, 4 ; * ete ee a i see Ee Mig SMI Cs eal emer) a Sak bah “t 7 oes © § 5] THE ALIPHATIC HYDROCARBONS wa? course of a few seconds, and may become too rapid unless the flask is cooled slightly from time to time. a. Test the inflammability of the gas. What caused the slight green mantle of the flame? Would pure methane burn with a green flame [R]? b. Describe two other methods of preparing methane. c. How could you prepare chloroform from methane? What name is given to this process? d. Define the term “alkyl,” and point out the relation which alkyl groups bear to the formule of paraffine hydrocarbons. e. How does Kekulé’s hypothesis of the linking of the carbon atoms explain the fact that dimethyl and ethyl hydride were found to be identical? B. Series of Olefine Hydrocarbons. ~ 6. Preparation of Ethylene from Ethyl Alcohol. Pour 25c.c. - of absolute ethyl alcohol into a 1-liter flask, and add 75 c.c. of pure concentrated sulphuric acid in small portions, constantly shaking the mixture. Should the mixture become decidedly warm, cool the flask under the water-tap before you add more acid. Why is it dangerous to pour alcohol or water into con- centrated sulphuric acid? Select a stopper which fits the opening of the flask snugly, and bore two holes in it, — one for the thermometer, and one for a doubly bent delivery-tube which leads to the first of a train of two wash-bottles. Fill each wash-bottle about half- full of a concentrated solution of sodium hydroxide. The gas should pass from the first wash-bottle to the bottom of the sec- ond, and from the second wash-bottle, by means of a long, bent delivery-tube, to a pail of water, or a pneumatic trough, where it should be collected in bottles over water. See that the bulb of the thermometer dips below the surface of the liquid in the flask. When you are sure that all connections are tight, heat the flask cautiously over a wire gauze, or a sand-bath, until the temperature reaches 180°. Regulate the flame so that the tem- perature may be maintained as nearly as possible at this point, and apply the heat so that a constant stream of gas is obtained, without any violent foaming of the reaction mixture. When a sample of gas collected in a test-tube over water, 12 THE ALIPHATIC HYDROCARBONS [§ 6 burns quietly, fill two 8-ounce tincture bottles and one 8-ounce wide-mouthed bottle with the gas. While you take the appa- ratus’ ‘apart, notice the odor of the charred product and gases in the generator flask. Does this suggest the necessity for using pie hydroxide in the wash-bottles? a. Pour 1 c.c. of bromine water into one of the tincture bottles. Close the bottle with a stopper, and shake it vigor- ously. Notice the odor of the colorless liquid. Is there any visible evidence of the separation of a new substance? How would bromine act upon a solution of sulphurous acid? b. Into the second tincture bottle, pour 1 c.c. of a very dilute solution of potassium permanganate (just rose color), and add 1 c.c. of a solution of sodium carbonate. Close the bottle and shake it. What change occurs? (This is known as von Baeyer’s reaction for the “double bond.’’) c. Place a wide-mouthed bottle of the gas on the table, and kindle the gas. From the mouthpiece of a water-bottle, imme- diately pour a stream of water into the bottle. This will dis- place the gas so that a conspicuous flame may be produced. Is the flame distinctly luminous? d. By means of a rubber tube connected with a gas-cock, fill two tincture bottles with illuminating-gas. To the gas apply the tests described in a and 6. Can you detect any unsatu- rated substance in the gas? What are the chief “ illuminants ”’ in coal-gas? e. W. ‘hat: would be formed by the action of concentrated sulph C acid upon ethylene? Does this product differ from the chief compound formed by the action of sulphuric acid upon ethyl alcohol at room temperature? How could you con- vert ethylene into ethyl alcohol? 6. Chemical Behavior of Paraffine and Olefine Hydrocar- bons Compared. a. To 5 c.c. of amylene, gradually add a solution of bromine (5 per cent.) in carbon tetrachloride. b. Add a few drops of this same bromine solution (5 per cent.) to 10 c.c. of dry petroleum ether (ligroine) the boiling-point of _ which lies between 40° and 60°. What is the chief constitu- ent of petroleum ether of this boiling-point? [R]. Divide the mixture into two equal portions, by pouring one half of it into a second dry test-tube. Allow one tube to stand in a dark =! tots e ; \ 2 *. 4 VW “I be ~ * . : ra) y if ( ‘ j + .’ £ a « fy e ho ee i ” “ , é F § 7] THE ALIPHATIC HYDROCARBONS 13 place in the cupboard of your desk, and expose the other tube to direct sunlight. After a few minutes, compare the solutions in the tubes. Breathe across the top of the tubes. What causes the cloud of vapor? What differences do you observe in experiments a and 6? Explain them. c. How would ethane and ethylene behave when treated with bromine? Is this behavior typical of the two classes of hydrocarbons of which ethane and ethylene are representatives? By what differences in graphic formule do we picture to our- selves this difference in behavior? d. By what series of chemical reactions could you convert ethane into ethylene, and the reverse? e. Upon analysis, a certain hydrocarbon was found to have the following percentage composition: — Carbon = 92.37 per cent.; hydrogen = 7.63 per cent. What is the simplest empirical formula of this hydrocarbon? The vapor-density (air = 1) was found to be 0.9. What would be the molecular weight, and the formula of this hydrocarbon? f. If it were found by experiment that 13 g. of this hydro- carbon absorbed 160 g. of bromine, how would you arrive at an equation expressing the course of the reaction, and a formula for the addition product? C. Series of Acetylene Hydrocarbons. “ 7. Acetylene: Its Preparation from Calcium Carbide. [H]. Fit a clean, dry flask with a stopper having two openings. Through one of these openings introduce a dropping-funnel; through the other, a tube leading into an empty wash-bottle, where it should end just below the stopper. This empty bottle serves to prevent water from running back through the delivery- tube upon the carbide. When 5 g. of calcium carbide have been placed in the flask, permit water to flow, drop by drop, upon the carbide. [Caution!] Do not allow a large quantity of water to come suddenly into contact with the carbide. Do not allow the acetylene to escape any more than is neces- sary, for the gas is not only offensive, but also poisonous. As soon as a sample of the gas, collected in a test-tube, burns quietly when ignited, fill two tincture bottles and one wide- mouthed bottle with it. 14 THE ALIPHATIC HYDROCARBONS [§ 7 a. Burn the gas contained in the wide-mouthed bottle. b. To the second bottle of the gas, add a little bromine water. When the color of the bromine is entirely discharged, notice the odor of the liquid. Is there any visible evidence of the forma- tion of a new compound? How does the behavior of acetylene toward bromine compare with that of ethylene and of ethane toward the same reagent? [RI]. c. Cuprous Chloride and Cuprous Acetylene. Dissolve 5g. of cupric oxide in 20 ¢.c. of concentrated hydrochloric acid. When the oxide has dissolved, add 5 g. of copper turnings, and boil the acid until the green color of the solution changes to dark-brown. Pour the solution of the copper salt into a beaker containing water. A white precipitate of cuprous chloride will be formed; by decantation, this should be separated from the acid solution, and dissolved in ammonium chloride and am- monia.* Pass acetylene into 5 ¢.c. of this solution. What is formed? [R]. Collect this precipitate upon a small filter, wash it, and dry it. When it is dry, heat a small piece of it in the flame. d. Can acetylene be prepared by the direct union of carbon and hydrogen? [R]. How could you obtain acetylene from ethane, and from ethylene? * If desired, the solution of cuprous chloride may be made as fol- lows: —To 1 g. of copper sulphate, dissolved in a little water, add about 4 c.c. of concentrated ammonium hydroxide solution and 3 g. of hydroxylamine hydrochloride. Dilute the solution with water until its volume is about 50 ¢c.c. It may be kept colorless by placing it in a tightly-corked bottle containing some copper turnings. ¥ Ld fi 5 bel : VP te hams CHAPTER III. HALOGEN COMPOUNDS. — HALOGEN ALKYLS. *8. Tests for the Halogens in Organic Compounds. a. To a dilute solution of ethylammonium bromide, add a few drops of a solution of silver nitrate. (?) b. Add a drop or two of ethyl bromide to a solution of silver nitrate. No immediate precipitate is formed. Explain. Allow the mixture to stand, and observe what happens. Add asolu- tion of silver nitrate to a solution of potassium bromide. What difference do you observe in the behavior of ethyl bromide and potassium bromide? Which of the two is more like ethyl- ammonium bromide in behavior? Explain. c. Dissolve 1 g. of potassium hydroxide in 10 c.c. of alcohol. By means of nitric acid, acidify 1 ¢.c. of this solution, known as “alcoholic potash,” and add a few drops of a solution of silver nitrate to it. Is any precipitate formed? What impurities, capable of giving a precipitate with a nitric acid solution of silver nitrate, are often present in potassium hydroxide? d. To 1 c.c. of alcoholic potash, add several drops of ethyl bromide, and boil the liquid gently for two minutes. After diluting the liquid with water, acidify it with nitric acid, and add 3 or 4 drops of a solution of silver nitrate. Compare the result with that obtained in 6. e. Repeat experiment d, but use a drop of phenyl bromide (brom benzene) in place of ethyl bromide. If an oil separates when water is added, enough alcohol should be used to dissolve this oil completely. Then add not more than three or four drops of a solution of silver nitrate. Can bromine in phenyl bromide be detected by this process? f. Seal a piece of copper wire into the end of a short piece of glass rod. Heat the wire in a Bunsen flame until it ceases to color the flame; dip it into an organic substance which contains a halogen, and heat it again. Test chloroform and phenyl bromide in this way. 15 16 HALOGEN COMPOUNDS [$ 9 g. What would be the effect of heating organic compounds containing halogens with a mixture of fuming nitric acid and silver nitrate in closed vessels at high temperature? How would ignition with calcium oxide affect such compounds? 9. Ethyl Iodide. Place 2 g. of red phosphorus in a small flask, and pour upon it 10 c.c. of absolute ethyl alcohol. Add 17 g. of powdered iodine, a portion at a time. Shake the flask after the addition of each portion, and cool it carefully before adding the next portion. When the mixture ceases to become warm spontaneously, cork the flask, place it in a beaker of cold water, and let it stand for 24 hours. Then connect the flask with a reflux-condenser, place it in a water-bath, and heat the water in the bath until the iodide begins to boil. (Cf. Fig. 2.) When the iodide has boiled for 15 minutes, change the position of the condenser, and distill the iodide. [R]. At first apply a gentle heat; finally, heat the bath until the water in it boils vigorously. When the liquid ceases to pass into the receiver, transfer the crude product to a small separatory-funnel or a dropping- funnel. [Instructions]. Wash the iodide twice with cold water; then, with a dilute solution of so- dium hydroxide until the brown color, caused by iodine, is en- tirelyremoved. Whatimpurities are eliminated by these opera- tions? After washing the iodide once more with water, separate it as completely as possible from the water, and place it in a dry ide flask with solid (not porous) Fig. 4. Separatory-Funnel. fused calcium chloride which has been broken into pieces about as large as grains of wheat. It usually requires several hours to dry such preparations completely. Distill it when it is dry. A distilling-flask provided with a thermometer should be used in this distillation. [R]. Observe the boiling-point, and compare ° § 10] HALOGEN COMPOUNDS 17 it with the recorded boiling-point of ethyl iodide. Weigh the pure, distilled iodide, and calculate the amount which should have been obtained if all of the alcohol had been changed into iodide according to the equation. a. Is the iodide heavier, or lighter, than water? b. When treated with a dilute solution of silver nitrate, does ethyl iodide immediately give a decided precipitate of silver iodide? c. Can you suggest any other ways of preparing ethyl iodide? How could you make ethyl bromide? propyl chloride? d. What would be formed if ethyl iodide were treated with zine dust and dilute alcohol? y 10. Action of Light upon Ethyl Iodide. Select three small ‘ test-tubes of approximately the same size. See that they are dry and clean. Put in each tube about 2 c.c. of the freshly distilled, colorless iodide. Cork the tubes immediately; and place one in direct sunlight, one in diffused light on the desk, and the last one in a dark cupboard or drawer. After 15 min- utes, compare the samples of iodide in the three tubes. Return the tubes to their respective places; and, at the end of the laboratory period, compare them again. When the third tube has been kept in the dark for several days, observe whether any change in the color of the iodide has occurred. Why is it customary to preserve iodides in brown bottles? How do you explain the fact that metallic mercury will dis- charge the brown color which ethyl iodide acquires on exposure to light? CHAPTER IV. MONATOMIC ALCOHOLS AND ETHERS. 11. Reactions of Alcohols. a. After acidifying 1 or 2 ¢.c. of a very dilute solution of potassium dichromate with sulphuric acid, add a few drops of alcohol, and boil the solution gently. What changes do you observe? What causes the odor of the mixture? [R]. What class of alcohols will give similar oxidation products? What would be formed by the careful oxidation of isopropyl alcohol? b. Place 1 or 2 c.c. of ethyl alcohol in a test-tube, and add 0.5 g. sodium [S.R.] cut into small pieces. [Carz!] What gas escapes? When the sodium has disappeared completely, cool the solution. What separates? [R]. Try the same experiment with methyl alcohol in place of ethyl alcohol. Is the reaction which takes place in these two cases a characteristic reaction of alcohols? (Cf. glycol, glycerol.) c. Mix a few crystals of sodium acetate with a little concen- trated sulphuric acid; add a small quantity of ethyl alcohol to the mixture, and heat it gently. Pour the product upon a watch-glass containing 4 or 5 c.c. of water. Notice the odor of the liquid. What is formed? [R]. Try the same test, using amyl or butyl alcohol in place of ethyl alcohol. d. [H]. To one drop of benzoyl chloride, add three drops of a solution of sodium hydroxide and a few drops of ethyl alco- hol; warm the solution, and observe the odor of the mixture. In a similar manner, treat methyl alcohol with benzoyl chloride. This method of making esters is known as Schotten-Baumann’s reaction. What is the meaning of the term ester? In what Sense are the compounds formed in ¢ and in d to be classed as esters? Would you call ethyl iodide an ester? Why do we prefer to call compounds of this class esters instead of salts, or ethereal salts? 12. The Methyl Ester of 3,5-Dinitrobenzoic Acid. The odor of a compound, even if it be fairly characteristic, can rarely be depended upon to identify a compound with a high 18 > Sis f A . Kh * hy Ait ic aes §12] MONATOMIC ALCOHOLS AND ETHERS 19 degree of certainty. As a rule, liquids are not easily purified and separated when very small quantities are available. Chem- ists, therefore, usually prefer to prepare for identification some crystalline derivative of the compound under inspection. A solid can generally be purified by recrystallization, and, when pure, will have a characteristic melting-point. Heat 0.3 g. of 3,5-dinitrobenzoic acid and 0.4 g. of phosphorus pentachloride in a very small, dry test-tube, constantly moved above a low flame. Finally, boil the mixture gently for a minute. Pour the product at once upon a small, dry watch- glass. When the acid chloride [R] has solidified, remove the phosphorus oxychloride by pressing the crystals upon a piece of porous plate. Place the dry substance in a small test-tube, add eight or ten drops of methyl alcohol, and close the tube with a stopper. The reaction will be complete in a few minutes. To recrystallize the ester, place it in a small flask (60 c.c.), and pour over it about 20 c.c. of dilute ethyl alcohol (3 volumes of alcohol and 1 volume of water). Close the flask with a cork stopper through which an open glass tube, about a foot and a half long, has been inserted. This tube serves as an air con- denser to prevent appreciable loss of sol- vent. Immerse the flask in a water-bath and heat it until the alcohol boils. If the ester does not dissolve completely in the course of a minute or two, add a little more dilute alcohol, and heat the flask again. When sufficient alcohol has been used to dissolve all of the solid, — except, perhaps, a small amount of foreign material, — filter the hot solution rapidly through a small filter-paper to remove insoluble impurities, and cool the filtrate until the ester has sep- arated. Collect the crystals upon a Biich- ner funnel, and wash them with 4-5 c.c. of cold, concentrated alcohol. When the sub- _. Z stance is dry, the melting-point should be de- Fig.6. Biichner Fun- . > neland Filter-Flask. termined. The pure substance melts at 107°. Other esters of this acid may be employed to identify the corresponding alcohols. They may be prepared according to 20 MONATOMIC ALCOHOLS AND ETHERS [§ 13 the directions just given for the methyl ester. They have the following melting-points (uncorrected): — Ethyl ester, 92°-93°; normal propyl ester, 73°-75°; normal butyl ester, 64°: isobutyl ester, 83°-84°. Cf. ‘Appendix A, Table II. 13. Determination of the Melting-Point. Fill a small beaker two-thirds full of glycerol, or concentrated sulphuric acid, and place it upon a wire gauze on aring-stand. Passa thermom- eter through a small cork, and clamp it by means of this cork _ so that the bulb of the thermometer is immersed about mid- way in the glycerine. Bend a piece of glass rod of small diam- eter so that it forms a stirring-rod triangular at the base, and with a handle which reaches to the top of the beaker where it is bent at an angle. ~ Capillary-tubes for determining melting-points may be made best from a test-tube. Heat the test-tube in the blast lamp flame until the glass is quite soft; take it from the flame, and draw it out slowly enough to form a narrow tube about 1 mm. in diameter. Pieces of this capillary-tube about 3 inches long may be closed at one end to make the so-called “ melting-point tubes.”’ A small sample of a dry solid may be put into a tube by taking up a little of the substance with the open end of the tube and tapping the closed end upon the desk. If this small tube, with the sample in it, is then | placed against the thermometer in the bath of glycerol, the tube will cling to the side of the thermometer, and should be adjusted so that the sample is opposite the bulb of the thermom- eter. Some experimenters prefer to fasten the capillary-tubes to the ther- mometer. This may be done by means of a small rubber ring, made by cut- ting a narrow cross section from a piece of ordinary gas-hose. Gradually heat the bath of glycerol, and stir it constantly until § 15] MONATOMIC ALCOHOLS AND ETHERS PA the sample of solid softens; at this instant, observe the reading of the thermometer. Concerning corrections, cf. Appendix A, Table IT. Note 1.—For a complete account of the various methods em- ployed in the determination of melting-points, consult Government Bulletin 70, Hygienic Laboratory. A Study of Melting-point Determinations. By George Menge. Washington, 1910. 14. The Iodoform Reaction Applied to Alcohols. Dissolve one drop of the compound to be tested (e.g., ethyl alcohol) in 1 c.c. of water. Place this solution in a small test-tube (8 in.), and, for each cubic centimeter of test liquid, add two drops of a solution of sodium hydroxide (1:10). Make a solution of iodine by triturating in a mortar one part of iodine, five parts of potassium iodide, and fifteen parts of water. Drop some of this solution slowly into the cold alkaline solution under inspec- tion, until the liquid has assumed a pale yellow color. When this mixture has stood for two minutes, notice whether any iodoform has separated. At room temperature, isopropyl alco- hol and acetone give noticeable precipitates; secondary butyl alcohol forms a precipitate slowly. If no iodoform separates at room temperature, heat the solution slowly until a thermometer placed in it indicates a temperature of 60°. Maintain this temperature for one min- ute. If the color of iodine disappears, add more of the iodine solution until the yellow color is permanent. Should no pre- cipitate form, set the tube aside for two minutes. Ethyl] alco- hol yields an abundant precipitate; while allyl alcohol forms only a slight one; propyl, isobutyl, tertiary butyl, and isoamy]l alcohol will not give precipitates within the time prescribed. 15. Tertiary Butyl Alcohol from Acetone. Grignard’s Synthesis. Add 4 g. of magnesium turnings to 10 c.c. of dry ether, and pour into the mixture 10 c.c. of methyl iodide. Con- nect the flask at once with a reflux-condenser, and moderate the action by placing the flask in a bath of cold water. When the metal has nearly disappeared, cautiously add 12 ¢.¢. of dry ace- tone by pouring it in smalt portions through the condenser tube. After the reaction is completed, distill the ether. Acidify the residue with dilute sulphuric acid, and subject the product to distillation. Add solid sodium hydroxide to the distillate, and 22 MONATOMIC ALCOHOLS AND ETHERS [§ 16 separate the upper layer of impure tertiary butyl alcohol. After this has been dried by means of solid sodium hydroxide, distill it. Collect the fraction boiling between 75° and 84°, and freeze it in a mixture of ice and salt. The yield is usually 40-50 per cent. The boiling-point of pure tertiary butyl alcohol is 82.5°. When pure, it melts at 29°. 16. Diethyl Ether. Caution! Ether is extremely imflam- mable. Great care must be taken to keep flames away from any apparatus containing it. Provide a flask with a stopper which has three openings. Through one of these openings insert a thermometer far enough to reach to the bottom of the flask; through a second opening, pass a tube bent at the proper angle to connect the flask with a condenser; through the third open- ing, introduce the dropping-tube, long enough to reach nearly to the bottom of the flask. Connect the flask with a condenser which dips into a receiver surrounded by ice-cold water. Put into the flask a mixture of 75 c.c. of absolute alcohol and 75 c.c. of pure, concentrated sulphuric acid, and heat the flask over a sand-bath until the thermometer indicates a temperature of 140°. During the entire operation, the temperature must be maintained between 140° and 145°. When the temperature has reached this point; and is prac- _ tically constant, by means of a cork fasten a dropping-funnel to the upper end of the dropping-tube, and fill the funnel with alcohol; then allow 100 c¢.c. of alcohol to flow, a drop at a time, to the bottom of the flask. Continue the heating for a few minutes after all of the alcohol has been added. When this a as Naar ih) § 16] MONATOMIC ALCOHOLS AND ETHERS 23 operation is finished, remove the stopper of the flask and notice the odor of the vapors which escape. Explain. Place the distillate in a separatory-funnel, and wash it sev- eral times with small portions of a strong solution of sodium chloride to which a little sodium hydroxide has been added. (?) Finally, shake it several times with small quantities of cold water. What is the specific gravity of ether? [R]. Which layer is ether? The purified ether should be separated, dried over porous calcium chloride for 24 hours, and distilled. What is the boiling-point of pure ether? a. Shake 2 ¢.c. of ether with 2 c.c. of water. Add 20 c.c. of water, and shake the mixture again. Result? Place 7 c.c. of water in a small, narrow test-tube, and mark the height of the water by means of a narrow strip of a label. Add 3 e.c. of ether, close the tube, and shake the mixture vigorously. When the ether has separated, paste another narrow strip of label on the tube to mark the line of separation between water and ether. Empty this mixture out, and repeat the experiment, using 7 c.c. of a saturated solution of salt in place of water. Is there any difference in the amount of ether dissolved by water and by salt solution? Explain. b. What intermediate compounds are formed by the action of sulphuric acid upon alcohol? To what class of compounds do they belong? c. How do you account for the formation of sulphur diox- ide and of carbonaceous products in this experiment? What would be formed in large quantities if the temperature of the experiment were 180° instead of 140°? * d. Can you suggest any other methods which might be used to prepare diethyl ether? How could you obtain dimethyl ether? methyl ethyl ether? e. By means of graphic formule, point out the relations which diethyl ether and ethyl alcohol bear to water. How could you change diethyl ether into ethyl alcohol? f. An analysis was made of a compound composed of carbon, hydrogen, and oxygen. An interpretation of the quantitative results and a molecular weight determination led to the em- pirical formula C,Hi0. When this substance was treated with * J. U. Nef, J. Am. Chem. Soc. 26, 1549; 30, 645. = 24 MONATOMIC ALCOHOLS AND ETHERS [§ 17 concentrated hydriodic acid, it gave three compounds: (a) CHslI; (b) CsH7I; (c), H:O. When these two iodides (a) and (b) were acted on by metallic sodium (Wiirtz reaction), a hydrocarbon was formed which was found to have specific properties entirely dif- ferent from those possessed by an isomeric hydrocarbon obtained by the interaction of metallic sodium and ethyl iodide. What is the probable constitutional formula of the first hydrocarbon, and of the original compound of the empirical formula C,H 00? 17. Absolute Ether. After shaking in a separatory-funnel 500 c.c. of ordinary ether and 10-15 c.c. of water, draw off the water, and make the following test with it. To a portion, add a little iodine dissolved in a solution of potassium iodide. When sodium hydroxide has been added until the brown color of the iodine has just disappeared, warm the solution gently for a minute or two. Notice the odor of the solution and the formation of the slight precipitate. Explain. After washing the ether six or eight times with small quan- tities of a solution of sodium chloride, transfer the ether to a bottle, and add porous calcium chloride to it. Allow the ether to remain in contact with the calcium chloride for twenty-four hours. Decant the ether into a clean, dry flask, and add sodium wire made with a sodium press, or thin pieces of sodium. ~ Protect the contents of the flask by an open calcium chloride tube inserted through the stopper. The ether should remain over sodium until the evolution of the gas, which may be quite appreciable at first, has ceased entirely. Caution! Do not pour water into the flask containing the so- dium residue. To remove the sxe sodium, add alcohol until the me- Fig. 9. Sodium Press. tallic particles have entirely disap- peared; then add water. After placing the ether in a clean, dry flask containing 2-3 g. of sodium, it may be distilled and collected in an appropriate receiver. (Cf. §2, Absolute Alcohol.) The flask containing the ether should be surrounded by water which has been heated to 50° or 60°; a long condenser should be used. CHAPTER V. ALDEHYDES AND KETONES. Aldehydes. 18. Oxidation of Methyl Alcohol Catalytically Induced by Platinum. Pour 5c.c. of methyl alcohol into a 250-c.c. Soxhlet flask. Wrap a fine platinum wire around a glass rod of small diameter, so that a spiral about 2 cm. long is formed in the middle section of the wire. Fasten one straight end of this wire around a short piece of glass rod. The length of this straight wire and spiral should be adjusted so that the tip-end of the wire barely touches the surface of the alcohol when it is lowered into the flask and the rod rests upon the top of the E Fig. 10. flask. Fold a piece of thin asbestos paper so that it forms a trough large enough to cover the mouth of the flask when it is placed loosely upon it. Heat the platinum wire in a Bunsen flame, lower it quickly into the flask, and cover the flask immediately with the asbestos roof. The odor of the formaldehyde will become apparent at once. If the air supply is properly regulated by adjusting the asbestos cover, the platinum wire will continue to glow for quite . a while. After some time, if the liquid in the flask is evapo- rated, a slight solid residue of paraformaldehyde will remain. 19. Formaldehyde from Methyl Alcohol. A Test for Small Amounts of Methyl Alcohol. Dissolve two drops of methyl 25 26 ALDEHYDES AND KETONES [§ 20 alcohol in 3 c.c. of water contained in a small test-tube. Make a compact spiral of fine copper wire by wrapping it about a glass rod. The spiral should be about 2 cm. long, and should have a straight piece about 20 cm. long. Oxidize the spiral by moving it rapidly through a Bunsen flame, and plunge the red- hot wire into the alcohol solution; repeat this operation several times. Pour this liquid into a small test-tube, and add one drop of a 0.5 per cent. solution of resorcinol. Cautiously pour this mix- ture into a second test-tube which contains 4 or 5 c.c. of concentrated sulphuric acid. If the second tube is properly inclined, the mixture will form a distinct layer upon the sur- face of the acid. A red zone, slightly violet in color, will appear; and above the zone there will be a light flocculent precipitate. This re- action is characteristic of formaldehyde; other aldehydes do not show this behavior. 20. Formaldehyde. (For two students.) Place 25 c.c. of methyl alcohol in a small distilling-flask, and close the flask with a stopper through which an open glass tube passes to the bottom of the flask. The side tube of the flask should be con- nected with a piece of hard-glass tubing, in which has been placed a layer of oxidized copper turnings 2 inches long. To oxidize the copper turnings, hold a bundle of them in a pair of crucible tongs, and move them for a few seconds to-and-fro in the flame of a Bunsen burner. (The turnings are usually coated with grease, which should be burned away hefore they are used.) Close the other end of the hard-glass tube with a stopper and a delivery-tube which leads through a stopper to the bottom of an empty 8-ounce bottle surrounded by a mixture of ice and salt. Through a second opening in the stopper of the bottle, pass a short tube bent at right angle. Be sure that all of the connections are tight. How can you test the apparatus to determine this? When the tube which leads from the bottle has been attached to the filter-pump by means of a piece of rubber tubing, heat the copper turnings to redness. Place the distilling-flask in a bath of water heated to 65° or 70°, and aspirate a slow stream of air through the entire apparatus, until the alcohol in the dis- tilling-flask has completely volatilized. Be careful not to allow § 21] ALDEHYDES AND KETONES 27 any condensed alcohol to run down upon the red-hot tube; the tube may break if you do. A loose plug of asbestos placed at each end of the hard-glass tube may prevent this accident. The solution which condenses in the bottle will contain about 40 per cent. formaldehyde; some methyl] alcohol and a little formic acid will be present. a. Filter the liquid. Place most of the solution in an evaporat- ing-dish, and evaporate it over a water-bath. What is left? [R]. b. Add a little of the formaldehyde solution to an ammoniacal solution of silver nitrate, and warm the mixture. To prepare ammoniacal silver nitrate, take a few drops of a solution of silver nitrate, and add ammonium hydroxide to it drop by drop, until the precipitate which forms at first has just dissolved. _c. To a dilute solution of formaldehyde, add a few drops of a 1 per cent. solution of phloroglucinol; then make the solution slightly alkaline by means of sodium hydroxide. No equation need be written. 21. Test for Formaldehyde in Milk. Put 10c.c. of the milk to be tested into a casserole or small porcelain dish, and add 10 c.c. of concentrated hydrochloric acid which contains 1 drop of a 5 per cent. solution of ferric chloride. Hold the casserole just above a small Bunsen flame, and keep it moving in a rotary fashion until the liquid just reaches the boiling-point. Should formaldehyde be present, a violet color, more or less pronounced, will appear when the temperature reaches 80° or 90°. In the absence of formaldehyde, the liquid will assume a turbid yel- lowish-brown hue. (Leach’s method.) 28 ALDEHYDES AND KETONES [§ 22 This test may be carried out somewhat more simply as fol- lows: — Add a few drops of a 5 per cent. solution of ferric chlo- ride to some commercial sulphuric acid. Place the milk to be tested in a large test-tube, and pour into it rapidly 10 c.c. of the prepared acid. If formaldehyde is present, the heat of mixing will be sufficient to develop the violet color. (Hehner’s method modified.) 22. Oxidation and Reduction Cell with Formaldehyde and Silver Nitrate.* Apparatus:— Two small beakers of about 60 ¢.c. capacity; a U tube made by bending the ends of a piece of glass tubing about 4 inches long and 8 mm. in diameter, so that arms 1 inch long are formed; two electrodes made of platinum- foil welded to pieces of platinum wire; a sensitive galvanometer. Pour some formalin solution into one beaker, and a solution of silver nitrate into the other beaker. Fill the bridge with a dilute solution of potassium nitrate, and close the ends by loose rolls of filter-paper. The bridge should be completely filled with this solution. Place the bridge across the beakers, so that the arms dip below the surface of the liquids in the beak- ers. Immerse a platinum electrode in each beaker, and con- nect the terminals with the galvanometer. A slight deflection of the needle will be observed. * For an account of the details of this experiment, and a proposed ionic mechanism whereby alkalies are thought to increase the reducing power of formaldehyde, consult an article by J. Stieglitz, Science, Vol- ume 30. § 23] ALDEHYDES AND KETONES 29 If sodium hydroxide is added to the formalin solution, a very appreciable increase in deflection will be produced, showing that the reducing effect of the formaldehyde is increased by alkalies. On the other hand, the oxidizing effect of the silver nitrate solution may be assumed to depend upon the concentra- tion of silver ions. If this be correct, any reagent which will suppress silver ions should diminish the oxidizing value of this solution. This may be shown by adding ammonium hydroxide — usually employed in the reduction test of aldehyde — to the silver nitrate solution in the beaker; an immediate decrease in the de- flection of the needle will be noticed. The formation of complex silver-ammonium ions diminishes the concentration of silver ions. 23. Methylal, Formaldehyde Acetal. Mix 15 g. of para- formaldehyde, 50 g. of methyl alcohol, and 1.5 g. of anhydrous ferric chloride. Place the mixture in a flask attached to a a c Fig. 13. a. Linnemann’s Apparatus; 6. Hempel Tube; c. Glinsky Tube. reflux-condenser, and heat it for 5-6 hours. Subject the reac- tion product to distillation, and collect all that passes over below 64°. Redistill the liquid, using a fractionating-column, and collect the low-boiling fraction separately. If this low- boiling portion is placed in a flask connected with a reflux- condenser, and is treated with small pieces of metallic sodium, 30 ALDEHYDES AND KETONES [§ 25 it will be freed from methyl alcohol, and will boil, for the most part, between 41° and 43°. The boiling-point of pure methylal is 42°. The yield should be about 90 per cent. a. Does methylal have the odor of formaldehyde? b. Would you call methylal an ether; if so, to what alcohols is it related? c. Does methylal reduce an ammoniacal solution of silver nitrate? 24. Action of Concentrated Sulphuric Acid upon Methylal. In a small, dry test-tube, treat three drops of methylal with two drops of concentrated sulphuric acid. Heat the acid gradually until it just begins to show signs of boiling. What is the solid white residue deposited upon the cool walls of the tube? Notice the odor of the gas. 25. Acetaldehyde. The Preparation of Aldehyde Ammo- nia. (For two students.) If this preparation is commenced, it must be carried in one operation as far as the point marked ®. It is impossible to interrupt the process at any previous point in the experiment. Gradually add 75 c.c. of concentrated sulphuric acid to 300 c.c. of water. When the mixture is cold, add to it 125 c.c. of alco- hol, and cool the solution thoroughly. Put 100 g. of potassium dichromate, broken into coarse granules, and 50 c.c. of water into a one-liter flask; surround the flask with a freezing-mixture of ice and salt. Pour the mixture of alcohol, acid, and water into a dropping-funnel, and allow it to flow upon the dichromate slowly, and with frequent shaking of the flask. When all the alcohol has been added, allow the flask to remain in the freezing- mixture for 15 minutes. During this interval, select a sound stopper for the flask. Pass a safety-tube and an adapter through the stopper, connect the adapter with a condenser inclined at an angle of 40°-50°, and fill the condenser jacket with water which has a tempera- ture of about 30°-40°. To maintain this temperature during the latter part of distillation, it will be necessary to run a little tap-water into the condenser from time to time. At the upper end of the condenser, insert a long tube which leads to a filter- flask half filled with ether, and surrounded by a freezing-mixture. Before you remove the flask from the freezing-mizture ask for instructions. When the freezing-mixture is removed, the con- § 25] ALDEHYDES AND KETONES ol tents of the flask may soon begin to boil; and unless the boiling is regulated immediately by cooling, the action will quickly become so violent that an explosion may result. It is usually necessary to warm the flask very gently. But as soon as the first signs of boiling are noticed, remove the flame at once, and raise the freezing-mixture until it touches the lower part of the flask. In this way, the spontaneous boiling, caused by the heat of chemical action, may be controlled, until the mixture will boil quietly of its own accord. Finally, apply a small flame, which may be raised gradu- ally until a large flame can be used with safety. When the aldehyde has been driven into the ether, disconnect the flask, and notice the odor of the liquid in it. Do you recognize the most pronounced odor? How do you account for its presence? If, for lack of time, it is impossible to continue the prepara- tion, the filter-flask which contains the ether solution of alde- hyde may be closed air-tight and placed in a cold place un- til the next laboratory period. ®. Surround the filter-flask r_ with ice and salt, and satu- rate the ether with dry am- monia gas obtained from a cylinder. [Instructions]. To avoid stoppage, pass the am- monia into the ether through a wide glass tube, best a straight calcium chloride tube. It will take fifteen or twenty minutes for this operation. After the crystals of aldehyde ammonia have been collected on a filter, wash them with ether, and dry them until all of the ether has completely Fig. 15. Vacuum-Desiccator. 32 ALDEHYDES AND KETONES [§ 26 evaporated. This may be done conveniently in a vacuum-des- iccator. While using ether, be careful to turn out all flames on your desk. 26. The Preparation of Pure Acetaldehyde from Acetalde- hyde Ammonia. Mix 10 g. of aldehyde ammonia, entirely free from ether, with 15 c.c. of water. Place this solution in a drop- ping-funnel, and let it flow, drop by drop, into a distilling-flask which contains 20 c.c. of water and 8 c.c. of concentrated sul- phuric acid. This mixture should be heated in a bath of boiling water while the solution of aldehyde ammonia is dropped into it. Pass the aldehyde through a condenser. The end of the condenser should reach to the bottom of a small distilling-flask which is completely surrounded by a freezing-mixture. [In- structions]. Use a few pieces of porous calcium chloride to dry the aldehyde; and redistill it without transferring it to another flask. After passing the aldehyde through a clean, dry condenser, collect it in a second distilling-bulb which is sur- rounded with a freezing-mixture. The boiling-point of acetalde- hyde is 21°. a. Reducing Action of Aldehydes. Clean a test-tube with a boiling solution of sodium hydroxide, and place in it 1-2 c.c. of Tollen’s reagent. Then add a drop or two of a very dilute solution of aldehyde. With proper precautions, one part of acetaldehyde may be detected in 250,000 parts of water. Cf. § 22. Note 2. — Tollen’s reagent may be prepared as follows: — Make a solution containing 0.3 g. of silver nitrate in 3 g. of water; and a second solution containing 0.3 g. of sodium hydroxide in 3 g. of water. Mix these two solutions, and keep the resulting solution in a dark place. It should not be heated. b. Add 1 drop of aldehyde to 3 drops of Fehling’s solution, and warm the mixture gently. What changes occur? Explain them. Note 3. — Fehling’s solution can be made by mixing equal vol- umes of the following solutions: —A solution of copper sulphate containing 34.64 g. in 500 c.c. of water, and a solution containing 180 g. of Rochelle salt and 70 g. of sodium hydroxide in 500 c.c. of water. ‘These two solutions should be mixed just before the reagent is used. § 27] ALDEHYDES AND KETONES 33 c. Polymerization of Aldehydes. By means of a stirring-rod moistened with concentrated sulphuric acid, add a trace, not a drop, of the acid to a little aldehyde cooled in a freezing-mixture. If the aldehyde is thoroughly cooled and stirred with a clean stirring-rod, it will finally solidify. Is the odor still like that of aldehyde? Explain this change. [RI]. d. ‘‘Resin’’ Formation. Warm a few drops of acetaldehyde with a concentrated solution of sodium hydroxide. How would dilute alkalies act upon acetaldehyde? upon formaldehyde? What is meant by the aldol condensation? e. Add 1 or 2 drops of acetaldehyde to 10 c.c. of water. To 1 c.c. of this solution, add 1 c.c. of Schiff’s reagent (rosaniline sulphite). Try the action of the same reagent upon a similar solution of formaldehyde. Note 4. — Schiff’s Reagent may be made by passing sulphur dioxide into a solution of 2.2 g. of rosaniline dissolved in 10 c.c. of cold water, until the solution is saturated with the gas. Rosaniline hydro- chloride or acetate may be substituted for rosaniline itself. Allow the solution to stand in a closed flask until it becomes colorless, or pale yellow. Then dilute it with 200 c.c. of water, and keep it in the dark in a tightly-stoppered bottle. .f 27. Chloral and Chloral Hydrate. How could chloral be ‘ prepared from acetaldehyde? from alcohol? Put 10 g. of chloral hydrate in a distilling-flask, and treat it with 10 c.c. of pure concentrated sulphuric acid. Distill the chloral which results. Use a small iron crucible as an air-bath to heat the flask uniformly. Pass the vapors through a con- denser, and collect the distillate in a small, dry distilling-flask protected by a calcium chloride tube which is attached to the side tube. Redistill the chloral, and determine its boiling-point. a. Mix the chloral with water in the proportions of one gram- molecular weight of chloral to one gram-molecular weight of water. b. Dissolve about one gram of chloral hydrate in a little water, and add to it a solution of sodium hydroxide. Identify the heavy liquid which separates. What does the alkaline solution contain? How could you test the accuracy of your conclusions? c. By means of the tests which you have just employed to characterize aldehydes, can you show that chloral is an alde- hyde? o4- ALDEHYDES AND KETONES L$ 30 Ketones. 98. Acetone. Addition of Acid Sulphites. Mix 10 c.c. of acetone with 15 c.c. of a cold saturated solution of sodium hydro- gen sulphite. Shake the mixture for several minutes and cool it if necessary. What is the crystalline substance? Only ketones whose formule contain the group CH;CO will respond to this test. Separate the crystals by filtration, and dry them on a piece of porous plate. Place this substance in a test-tube to- gether with an equal weight of sodium carbonate and 5 c.c. of water. Heat the solution and observe the odor. Do aldehydes form similar addition products with sodium hydrogen sulphite? See acetaldehyde, formaldehyde, benzaldehyde. [RI]. 29. Condensation. Dibenzylidene Acetone, Dibenzalace- tone. Put 5 drops of acetone, | c.c. of water, and 1 ¢.c. of benz- aldehyde in a test-tube, and add 5 c.c. of strong alcohol and 1.5 c.c. of a 10 per cent. solution of sodium hydroxide. After mixing these substances, heat the mixture over a flame until it has boiled gently for one minute. Cool the liquid, and shake it until there is a separation of crystals, which may then be collected upon a small filter and washed with 5 c.c. of strong aleohol. Recrystallize the product from strong alcohol (5 c.c.); collect the crystals on a filter, wash them with 2 c.c. of alcohol, and dry them upon a piece of porous plate. The melting- point of dibenzylidene acetone is 112°. This test is sometimes employed to detect small amounts of acetone (e.g., in urine). a. Treat a little benzalacetone with an excess of hydrochloric acid. In a similar way try concentrated hydriodic acid.* 30. Oxidation and Reduction of Acetone. a. Does acetone reduce Fehling’s solution or Tollen’s solu- tion? Does it color Schiff’s reagent? [RI]. b. What would be formed by the reduction of acetone? How is acetone prepared from calcium acetate? What would be formed if acetone were heated with dilute sulphuric acid and potassium permanganate? [R]. What relation doesacetone bear to propane? How could it be converted into propane? c. Acetone from Isopropyl Alcohol by Oxidation. Dissolve 0.5 g. of chromic anhydride (CrO;) in 2 c.c. of water, and add * Baeyer and Villiger, Ber. 35, 1190 (1902); Thiele and Strauss, Ber. 36, 2375 (1903). § 31] ALDEHYDES AND KETONES 30 0.3 c.c. of concentrated sulphuric acid. Put 6 drops of isopropyl alcohol in a small distilling-flask (15 ¢.c.), and cautiously add 0.5 c.c. of the chromic acid solutions to it. Cork the flask imme- diately, and incline it so that the side tube dips into a test-tube, and just below the surface of a solution containing 0.4 c.c. of water, 0.4 c.c. of benzaldehyde, and 2 c.c. of ethyl alcohol. Finally, heat the distilling-flask gently for a short time. To the distillate collected in the test-tube, add 0.5 c.c. of a 10 per cent. solution of sodium hydroxide, and boil the mixture for about one minute. Recrystallize the dibenzylidene acetone from alcohol (1 ¢.c.). Collect the precipitate, dry it, and deter- mine its melting-point (cf. § 29). sj 31. Acetoxime. Dissolve 10 g. of hydroxylamine in 20 c.c. of water, and pour into it a solution of 5.8 g., one equivalent, of sodium hydroxide dissolved in 15 c.c. of water. Keep the hy- droxylamine solution cold, and shake it while the alkaline solu- tion, in small portions, is poured into it. Add 11 c.c. of acetone, and allow the mixture to stand for 24 hours. The oxime will separate as a white solid. Collect the solid upon a Biichner funnel, and wash it once or twice with a little cold water. Extract the filtrate with ether, using about 20c.c. Pour the ether extract through a dry filter- paper, and allow the ether to evaporate spontaneously. The total amount of solid obtained should be about 6g. The oxime is quite volatile at room temperature, and should be preserved in closed vessels. It may be recrystallized from ligroine which boils between 40° and 60°. a. Carefully dry a small amount of recrystallized oxime in a desiccator, and determine its melting-point. Acetone is fre- quently identified by converting it into acetoxime. b. What would be formed by reducing acetoxime, provided metallic sodium and alcohol were used as the reducing agent? c. What significance do oximes have for the study of alde- hydes and ketones? How could aldehydes and ketones be recovered from their respective oximes? Note 5.— In this preparation, it is necessary to use sodium hydrox- ide and the hydroxylamine salt in equivalent amounts, since acet- oxime cannot be extracted from an alkaline solution. (?) In many cases in preparing oximes, an excess, even three or four times the calculated amount of alkali, is essential. In other cases, however, 36 ALDEHYDES AND KETONES [§ 32 an acid solution must be used; e.g., quinone in hydrochloric acid gives a dioxime; in alkaline solution, it is reduced. \{ 82. Hydrazones. Acetone Phenylhydrazone. Dissolve Ic.c. of freshly distilled phenylhydrazine in 0.5 c.c. of glacial acetic acid and 10 c.c. of water. Add 0.5 c.c. of acetone to 5 c.c. of water, and pour this solution into the phenylhydrazine solution. At first, a turbidity will result; and finally, an oil will separate. It may be extracted with ether. When the solution has been dried and the ether removed, acetone phenylhydrazone will be left as an oil. : Hydrazones are frequently employed to identify ketones and aldehydes. For this purpose, if phenylhydrazine does not yield solid crystalline hydrazones, it is the usual practice to choose some other hydrazine derivatives which will. Para-nitropheny1- hydrazine and para-bromphenylhydrazine have been especially useful in this respect. 33. Acetone Para-nitrophenylhydrazone. Dissolve about 0.5 g. of para-nitrophenylhydrazine in 5 ¢.c. of glacial acetic acid and 10 c.c. of water. Pour this solution into 50 c.c. of water con- taining 4 drops of acetone. The mixture will become yellow and turbid; and, in the course of thirty minutes, the crystals will separate completely. After the para-nitrophenylhydrazone has been collected upon a filter and washed, drain it, and re- crystallize it from a little hot alcohol. It forms golden-yellow crystals which melt at 148°. Because of the slight solubility of this hydrazone (.003 g. in 50 c.c. of water), it has been used to estimate acetone quantitatively, which can be done by drying and weighing the precipitated hydrazone. In this way, the distillate obtained from urine acidified with dilute sulphuric acid may be tested for acetone. CHAPTER VI. MONOBASIC FATTY ACIDS. ) 34. Formic Acid from Oxalic Acid. Heat 40 g. of glycerol in an open dish until a thermometer placed in the glycerol indicates - a temperature of 175°. When the glycerol has been cooled, pour it into a distilling-flask which contains a weight of crystallized oxalic acid equal to that of the glycerol. Introduce a thermom- eter so that the bulb is surrounded by the glycerol, and distill the mixture until the thermometer registers a temperature of 150°. The distillate is essentially dilute formic acid. At this stage, cool the liquid in the distilling-flask to 50°, and add a second portion of oxalic acid (30 g.). The mixture may then be heated as before. Place the combined fractions in a distilling-flask, and subject them to fractional distillation. Collect the fraction which boils between 105° and 108°. About what percentage of formic acid does this liquid contain? [RI]. a. Salts of Formic Acid. After a portion of the acid solution has been made almost neutral by means of sodium hydroxide, evaporate it nearly to dryness, and allow the salt to crystallize. b. To prepare the lead and copper salts, heat portions of the acid with the respective oxides, and filter the boiling solutions through small filter papers. Allow the filtrates to evaporate, and examine the salts which remain. Is the lead salt very soluble in cold water? . c. Reduction. Add a solution of silver nitrate to a little of the acid. To neutralize the acid add a slight excess of am- monia. Explain the change which takes place when the alkaline solution is warmed. d. Make a solution of sodium formate, and add a few drops of mercuric chloride to it. Warm this solution gently. The white precipitate which separates is mercurous chloride, HgCl. Collect it upon a filter-paper and moisten it with ammonium hydroxide. It will turn black. Is this characteristic of mercur- 37 38 MONOBASIC FATTY ACIDS [§ 36 ous chloride? [R]. The formates are not the only substances which reduce mercuric chloride to mercurous chloride. Explain the reactions which take place when sodium formate reduces mercuric chloride. [R]. Would it be possible to construct an oxidation-reduction cell with sodium formate and mercuric chloride? Cf. § 22, Formaldehyde. e. Decomposition by Sulphuric Acid. Heat a portion of the sodium salt with some concentrated sulphuric acid. What gas is evolved? Does it burn? f. What relation does formic acid bear to formaldehyde? to methyl alcohol? to carbonic acid? to methane? How could you convert methyl alcohol and formaldehyde into formic acid? -g. Could formic acid be prepared by oxidizing methyl alcohol, if a mixture of sulphuric acid and potassium permanganate were used as the oxidizing agent? Could anhydrous formic acid be prepared by distilling a mixture of sodium formate and concen- trated sulphuric acid? h. What is the best way to prepare the anhydrous acid? [RI]. Has formic anhydride ever been obtained? [RI]. 35. Formic Acid by the Oxidation of Methyl Alcohol. Make a mixture containing 30 c.c. of water, 10 ¢.c. of con- centrated sulphuric acid, and 12 g. of powdered potassium dichromate. Cool the mixture thoroughly, and add 2.5 c.c. of methyl alcohol. After a few minutes, heat the mixture on a water-bath for fifteen minutes. Distill the product until the residue becomes thick. Pour most of the distillate into a dish, and neutralize it by adding sodium carbonate to it. To make sure that the acid shall be in excess, add a few cubic centimeters of the distillate which have been kept in reserve for this purpose. Concentrate the salt solution until its volume is 10 ¢c.c., and apply the char- acteristic tests for formic acid described in the previous prep- aration. 36. Acetic Acid. Place 25 g. of fused sodium acetate in a dry distilling-flask, and add to it 15 ¢.c. of pure concentrated sulphuric acid. Even if so-called “fused” sodium acetate is taken, it must be re-fused just before the experiment. It should not be heated much above its melting-point; it will decompose and turn dark if this is not guarded against. When the flask has been connected with a condenser, heat the mixture of salt § 36] MONOBASICG FATTY ACIDS, 39 and acid on a sand-bath, and collect the distillate in a small, dry distilling-flask. Redistill the acid, and observe the boiling- point. a. “‘ Glacial Acetic Acid.” Pour a little of the fraction of highest boiling-point into a dry test-tube, and surround the tube with ice and salt. If the acid does not solidify at once, rub the walls of the tube with a stirring-rod. b. Salts and their Reactions. Make a strong solution of sodium acetate. To one portion of the solution, add a solution of ferric chloride, and boil the deep-red liquid; to a second por- tion, add a solution of silver nitrate. Results? Does acetic acid reduce ammoniacal silver nitrate? c. Dissolve a little pure sodium acetate in water and test the solution with neutral litmus paper. What is the reaction? How do you account for this? Make a concentrated solution of neutral soap, and add to it a few drops of phenolphthalein. Pour the mixture into a large volume of water. Explain the changes observed. d. Cacodylic Oxide. [H]. Heat a small crystal of sodium acetate with a minute quantity of arsenious oxide. Cacodylic oxide is formed. It is extremely poisonous. Be very careful when noticing the odor. [RI]. e. Is the vapor of acetic acid inflammable? Try to burn it. f. What is sugar of lead? How is it prepared? What are the commercial sources of acetic acid? g. Upon analysis, acetic acid and formaldehyde are found to have the same percentage composition: carbon, 39.78 per cent; hydrogen, 6.79 per cent.; oxygen, 53.43 per cent. Why do chemists assign the formula CH.O to formaldehyde, and the formula C,H,O2 to acetic acid? After you have collected the actual experimental data [R] by an inspection of the evidence for each, state the reasons in logical sequence. CHAPTER VII. DERIVATIVES OF FATTY ACIDS. 37. Methyl Ester of Formic Acid. Place 30 g. dry sodium formate in a small distilling-flask, and add to it a mixture of 10 g. of methyl alcohol and 32.5 c.c. pure, concentrated hydro- chloric acid (sp. gr. 1.2). To prevent an increase in temperature, surround the flask with cold water, and add the acid and alcohol slowly. Close the flask air-tight, and allow the mixture to stand in a vessel of cold water for 24 hours; then distill the ester from a water-bath; and, in a receiver cooled by means of ice, collect all that passes over until the vapor reaches a temperature of 70°. Keep the distillate cold, and add powdered calcium chloride to it as long as the solid dissolves. This usually causes the formation of two layers of liquid, which may be separated by means of a dropping-funnel. The upper layer, which is almost | pure formic methyl ester, should be placed in a small flask, together with some solid calcium chloride. When the ester is dry, pour it into a distilling-flask, and distill it. The boiling- point of the ester is 32°. a. Is the ester easily soluble in water? b. Does it have an acid taste or odor? c. What is the empirical formula of formic methyl ester? Compare this formula with the empirical formula of acetic acid. Compare the boiling-points, solubilities in water, and specific gravities [R] of the two compounds. Do they differ in their chemical behavior as well as in their physical properties? d. How does the behavior of this ester towards sodium hy- droxide differ from the behavior of acetic acid towards the same substance. [R]. How does this reaction help us in determining the constitutional formula to assign to formic methyl ester? What are the graphic formule of the two compounds? What name do we give to substances which bear this relation to one another? How do these formule represent the differences which 40 # § 39] DERIVATIVES OF FATTY ACIDS 4] have been observed in the chemical behavior of the acid and the ester? e. What acid bears the same relation to acetic methyl ester that acetic acid bears to formic methyl ester? ~/ 38. Acetic Ethyl Ester, Acetic Ether. In a distilling-flask, place a mixture of 20 c.c. of absolute alcohol and 25 c.c. of concentrated sulphuric acid. When the flask has been con- nected with a condenser, heat it on a wire gauze until a ther- mometer which reaches into the liquid indicates a temperature of 140°. The temperature must be kept between 140° and 145° during the process. Through a dropping-funnel, connected with the dropping-tube (cf. § 16, Diethyl Ether) which reaches to the bottom of the flask, allow a mixture of 25 c.c. of alcohol and 25 c.c. of glacial acetic acid to flow into the flask as rapidly as the ester distills into the receiver. After you have transferred the distillate to a large beaker, cautiously add a solution of sodium carbonate, and stir the mixture until effervescence almost ceases. Why? Sometimes the effervescence is very slight. By means of a separatory-funnel, separate the heavy layer from the lighter layer of acetic ether. Wash the ester several times with small portions of a strong solution of salt. Why? Distill the ester after it has been dried by means of porous cal- cium chloride. What is the boiling-point? [R]. What yield have you obtained? ‘ 39. Hydrolysis of the Ester. Put in a flask 5 c.c. of acetic ethyl ester, 2 g. of solid sodium hydroxide, and 50 c.c. of water. Connect the flask with a reflux-condenser and heat the alkaline solution for ten minutes. Then distill the solution until one- half of the liquid has passed over. What does the distillate contain? Empty the remainder of the alkaline solution into a porcelain dish, and evaporate it to dryness. What is this residue? Show by appropriate tests that your conclusions are correct? a. Could dilute mineral acids be used to accelerate the hy- drolysis of the ester? [RJ]. Are other esters affected in a similar manner by dilute acids and alkalies? 6. What influence would concentrated acetic acid have upon the completeness of the hydrolysis of the ester by water? c. Compare the method used in the preparation of acetic 42 DERIVATIVES OF FATTY ACIDS [$ 40 ethyl ester with that which was used to obtain diethyl ether. By equations and words, set forth any analogies which you may observe in the two processes, and any similarity in formule (type) of the ester and the ether. d. Mention two other methods which may be used to prepare acetic ethyl ester, and show that these methods also have their analogies among the methods used to prepare diethyl ether. Are these methods general in their application? e. There are two butyric acids which have the same empirical formula as acetic ethyl ester (CisH;O.). Write the constitu- tional formule of these three substances, and tell how you could distinguish and identify each one by properly chosen experiments, chemical and physical. Are there any other esters of fatty acids which have this same empirical formula (C,H;O;)? f. In what respects does the action of sodium hydroxide upon acetic ethyl ester resemble the action of sodium hydroxide upon the fats and oils? What are soaps? 40. Acetyl Chloride. Place 25 g. of glacial acetic acid in a distilling-flask. A second distilling-flask, which serves as a receiver, should be joined to the condenser-tube by means of a sound cork. To absorb any hydrochloric acid which may be evolved, and at the same time to prevent moist air from enter- ing the receiver, connect the side tube of the second distilling- flask with a long calcium chloride tube charged with soda-lime. Do not pack this tube too tight, and be careful that it does not stop up during the distillation. By means of a dropping-funnel, allow 20 g. of phosphorus trichloride to run into the acetic acid, and at the same time prevent the mixture from becoming too warm by surrounding the flask with cold water. When all of the trichloride has been added, immerse the flask for fifteen minutes in a bath of water heated to 40° or 50°; finally heat the water to boiling as long as the chloride distills. Redistill it, and observe the boiling-point. [R]. The yield varies from 20 to 25 g. a. Mix a few drops of the chloride with a few drops of water. Care! What gas escapes? What remains in the test-tube? How does the action of water upon acetyl chloride resemble the action of water upon phosphorus trichloride? b. Gradually add 1 c.c. of acetyl chloride to 2 c.c. of absolute alcohol. Make the solution slightly alkaline, pour it upon a § 41] DERIVATIVES OF FATTY ACIDS 43 watch-crystal, and notice the odor. What is formed? In what _ respect does this reaction resemble the action of acetyl chloride _ upon water? 41. Acetic Anhydride. When some “fused” sodium acetate has been re-fused, grind it to a fine powder, and put 20 g. of it into a distilling-flask. A condenser and a receiver similar to the ones used in the preparation of acetyl chloride should be used in this case also. After surrounding the flask by a bath of cold water, place 15 g. of acetyl chloride in a dropping-funnel; and, at intervals, allow one-half of this reagent to flow upon the acetate. To insure a thorough mixing of the two substances, remove the dropping-funnel, and stir the contents of the flask by means of a stout glass rod. The remainder of the chloride should then be added. In order to complete the reaction, attach the flask to a reflux- condenser, and heat it in a bath of boiling water for twenty minutes. Then arrange the condenser in the position for dis- tillation, and heat the flask in an oil-bath. Collect the acetic anhydride, and purify it by a second distillation. The boiling- point is about 138°. Approximately 20 g. should be obtained. a. Mix a few drops of the anhydride with water. Does it react with water more readily, or less readily, than acetyl chloride? Does the water solution contain any hydrochloric acid? How could you detect it? What would its presence indicate? How would you treat the anhydride to eliminate this impurity? b. Treat 1 c.c. of absolute alcohol with 1 c.c. of acetic anhy- dride, and warm the mixture gently. Add water to the prod- uct, and make it slightly alkaline. Pour it upon a watch- crystal, and notice the odor. What is formed? c. How is acetic anhydride used to determine the “ presence ’’ of hydroxyl groups in organic compounds? to determine the “number ’”’ of hydroxyl groups? How may acetyl chloride or acetic anhydride be changed into ethyl alcohol? d. Is there any method used to prepare ether which is analo- gous in principle to the methods which you have just employed © in making acetic anhydride? By words and by graphic formu- le, point out any similarity in ‘‘type” which you may perceive when the formule of diethyl ether, acetic anhydride, and acetic ethyl ester are compared. CHAPTER VIII. SULPHUR COMPOUNDS. 42. Ethyl Mercaptan. Warm 2 c.c. of a saturated solution of potassium ethyl sulphate with 2 c.c. of a solution of potassium hydrogen sulphide (33 per cent.). Notice the odor of the mer- captan. a. When subjected to oxidation, do the sulphur alcohols yield aldehydes and ketones? b. Do sulphur alcohols give olefines and ethers when they are heated with concentrated sulphuric acid? c. What is sulphonal? trional? tetronal? How is ethyl mer- captan used in their preparation? 43. Trimethylsulphonium Iodide. Dissolve 3g. of potas- sium hydroxide in 30 c.c. of methyl alcohol. Pour the solution into a flask (about 200 c.c.), weigh the flask and contents to the nearest 0.1 g., and pass hydrogen sulphide into it until 0.8 g. has been absorbed. Filter this solution into a somewhat smaller flask, connect it with a reflux-condenser, and add 5.5 c.c. of methyl iodide by pouring it in at the top of the condenser. Keep the mixture boiling gently for one-half hour. While the solution is still warm, pour it out of the flask, leaving the solid potassium iodide behind. Trimethylsulpho- nium. iodide will separate when this liquid has become cool. Recrystallize the salt from methyl alcohol. a. Does a solution of this compound in water give silver iodide or silver sulphide when it is treated with a solution of silver nitrate? Explain. b. How could you prepare the base to which this salt is related? Is it an active base? 44 CHAPTER IX. COMPOUNDS CONTAINING NITROGEN. 44. Tests for Nitrogen in an Organic Compound. In most nitrogenous organic compounds, the nitrogen may be detected with the greatest certainty by the formation of sodium or potassium cyanide. To complete the test, convert the cyanide into Prussian-blue. The test is usually performed as follows: — a. In a test-tube, heat to redness a few crystals of acetanilid with a small piece of sodium. [S.R.] Cool the fused mass, crush the test-tube in a dry mortar, and add 3 c.c. of alcohol. When the sodium has entirely dissolved, add water very cautiously. Care! Boil the solution and filter it if necessary. After adding to the filtrate a drop of a solution of ferrous sulphate and one drop of a solution of ferric chloride, warm it gently, and acidify it with hydrochloric acid. (To make sure that the solution is acid, test it with litmus paper.) If the acid solution is dis- tinctly blue, nitrogen is present. If it has a green color, allow it to stand for several hours; finally, a slight blue precipitate will form. b. In a test-tube, heat several crystals of urea with a small quantity of soda-lime. What gas is evolved? _ Amides. : )~ 45. Acetamide. Pour 50 g. of acetic ethyl ester into a flask containing 100 c.c. of strong ammonia-water (sp. gr. 0.90). When this mixture has become homogeneous, transfer it to a distilling-flask, and subject it to distillation. [H]. Put a few small pieces of porous plate into the flask to prevent ‘‘bump- ing,’ and heat the flask over a wire gauze. Keep the first fraction, and test it for alcohol. (?) When the temperature indicated by the thermometer is about 170°, take away the condenser, and put in place of it a long, wide glass tube without a jacket; then continue the distillation, and collect in a beaker all that passes over between 175° and 230°. If the amide does not solidify when it has cooled, it will 45 46 COMPOUNDS CONTAINING NITROGEN [§ 46 crystallize if you rub the walls of the beaker with a stirring- rod. To remove the liquid which adheres to the crystals, collect them upon a Biichner funnel connected with a filter- flask and a pump, and press them upon a piece of porous plate. Acetamide boils at 223°. What yield have you obtained? a. Recrystallize a small amount of acetamide with chloroform as the solvent. Determine the melting-point of the dry crystals. b. Heat a few crystals with a strong solution of sodium hy- droxide. Notice the odor. What gas is evolved? c. Heat a little acetamide with dilute sulphuric acid, and observe the odor. What is formed? Explain 6 and c. Nitriles. “46. Acetonitrile, Methyl Cyanide. Weigh out rapidly 10 to 15 g. of phosphorus pentoxide, and transfer it to a dry retort or to a distilling-flask. This can be done best by means of a wide cone made by twisting a smooth piece of writing paper. Add 10 g. of acetamide. By means of a thick glass rod, carefully mix these two substances thoroughly, and cover the mixture with a layer of 10 g. of phosphorus pentoxide. When a condenser has been connected with the retort, slowly heat the retort, either in a bath of Wood’s metal or with lumi- nous flame. The heat should be applied in such a manner that undue foaming of the mass may be prevented as much as possible. Finally, increase the temperature until the nitrile slowly distills into the condenser. Pour the distillate into one-half its volume of water, and shake the mixture. Powdered sodium hydroxide, added to the cold solution as long as it will dissolve, will cause the nitrile to separate as a lighter layer. It should be removed, dried with calcium chloride, and distilled over a little fresh phosphorus pentoxide. The boiling-point of acetonitrile is 81.6°. a. Does the nitrile affect litmus? b. Heat a small quantity of the nitrile with a solution of sodium hydroxide. What is the odor? Explain the result. c. Could you prepare acetonitrile from ammonium acetate without previously isolating acetamide? d. How are nitriles used to prepare organic acids? How could you pass from acetic acid to propionic acid by a series of reactions including this reaction? § 48] COMPOUNDS CONTAINING NITROGEN 47 e. By what experimental method could you change acetoni- trile into acetamide? f. Isonitriles: Cf. Amines and Chloroform. 47. Ester of Nitrous Acid. Ethyl Nitrite. Dissolve 5 c.c. of ethyl alcohol and 10 g. of sodium nitrite in 50 c.c. of water. Pour this solution into a distilling-flask connected with a con- denser and a receiver thoroughly cooled by means of ice. Heat the nitrite solution to a temperature of 20°-25°. Make a solu- tion containing 50 c.c. of water, 5 c.c. of concentrated sulphuric acid, and 5 c.c. of alcohol; pour it into a dropping-funnel, and allow it to flow slowly into the nitrite solution. Ethyl nitrite will distill. Its boiling-point is 17°. a. What product, isomeric with ethyl nitrite, would be formed by the action of ethyl iodide upon silver nitrite? How could you distinguish them by the difference in their behavior towards reducing agents? Nitroparaffines. 48. Nitroethane. What difficulties would you encounter in attempting to prepare nitroethane from ethane? Is it possible to obtain any nitroparaffines by the action of nitric acid on paraffine hydrocarbons? The Sodium Salt of Nitroethane. Dissolve 0.5 g. of nitroethane in a little alcohol, and add to it a solution of sodium ethylate, made by allowing 0.2 g. of sodium to act upon a few cubic centimeters of ethyl alcohol. After transferring the precipitate to a filter, wash it with a little cold alcohol, and finally, with ether. When the salt has been dried, make the following tests: — a. Heat a small piece of it on a spatula. b. Dissolve some of the salt in the water. To one portion of the solution, add a solution of mercuric chloride; to a second portion, add bromine water. c. Dissolve about one-half of the remaining salt in water, and add dilute sulphuric acid to it. What gas is evolved? Warm the solution, and observe the odor of the vapor which escapes. (?) d. Ethyl Nitrolic Acid. Dissolve the remainder of the salt in water, and add to the solution a few crystals of sodium nitrite; acidify the solution slowly by adding dilute sulphuric acid; then add sodium hydroxide to it until it reacts alkaline. What oi ? 7 48 COMPOUNDS CONTAINING NITROGEN [§ 51 causes the solution to assume a red color? How could you isolate ethyl nitrolic acid? Is it a colored substance? 49. Pseudonitroles. Mix a little silver nitrite with an equal volume of dry sand, and transfer it to a small distilling-flask (15 c.c.) with a side tube about 20 cm. long. Pour 8-10 drops of isopropyl iodide upon the nitrite, and close the flask at once. When the sudden evolution of heat has moderated, distill the product over a small flame. No condenser need be used. Col- lect the distillate in a long test-tube, and shake it with three times its volume of a solution containing potassium nitrite and a little potassium hydroxide. Add dilute sulphuric acid, a drop at a time, until the solution reacts acid. Make it alka- line once more, and acidify it again. The blue color is caused by a pseudonitrole, which may be extracted by chloroform. a. Cf. §48, c, Nitroparaffines. Is the difference in behavior towards nitrous acid observed in these two cases characteristic of primary and secondary nitroparaffines in general? 50. Brom-nitrosopropane. To a dilute solution of acetone, add a few drops of a 10 per cent. solution of hydroxylamine hydrochloride and 1-2 drops of pyridine. Pour upon this solution about 1 c.c. of ether, and add bromine water gradually until the ether assumes a yellow color. When a few drops of a solution of hydrogen peroxide are added, and the mixture is shaken, the ether will assume a blue color. The color is caused by brom- nitrosopropane. (This reaction is employed to detect small quantities of acetone. Sensitiveness: 1 mg. in 5 ¢.c.) The following equation expresses the course of the reaction. Ace- toxime, which is first formed, reacts with bromine. CHs. CH: . C = NOH+ Br.— C = NOBr + HBr. CH; ” CH; % Pyridine accelerates the rearrangement of the compound. CH; te C= NOR Neo as Br CH, ” CH; NO Hydrogen peroxide disposes of impurities. (Piloty, Ber. 35, 3099.) Amines. 61. Methylamine from Acetamide. (For two students.) Bromine must be handled with great care. Conduct the work § 51] COMPOUNDS CONTAINING NITROGEN 49 under a hood, and be careful not to breathe the bromine vapors or to spill any of the bromine on your hands. [Instructions!] Grad- ually add a cold solution of potassium hydroxide (25 g. of KOH in 100 c.c. water) to a mixture of 20 g. acetamide and 18 c.c. bro- mine (not bromine water). Keep this mixture cold while the potassium hydroxide is added, and stir it to prevent local heat- ing. If a precipitate separates at this point, add a little water to dissolve it, and proceed. When the mixture assumes a pale- yellow color, place it in a dropping-funnel, and allow it to flow in a slow stream into a flask containing 60 g. of potassium hydroxide dissolved in 180 c.c. of water. The temperature of the alkaline solution in the flask should be kept between 60° and 70°; it should not rise above 75°. Since considerable heat is evolved during the mixing of the solutions, it will be necessary to prevent over- heating, by cooling the flask from time to time. During this part of the operation, and throughout the preparation, the flask should be connected with a condenser. The lower end of the con- denser-tube should project into a receiver which contains a little ice-cold water, and should dip just below the surface of the water. When the mixture has been kept at this temperature until the solution in the flask is practically colorless, the amine may be distilled. Put afew small pieces of clay-plate in the flask, place it upon a wire gauze, and, at first, heat it very gently with a small flame to prevent a sudden evolution of methyl amine gas, which, by its pressure, may burst the flask. The heat must be in- creased very gradually. Finally, boil the solution for several minutes until all of the amine has passed through the condenser. a. Observe the odor of the solution collected in the receiver. Is it exactly like that of ammonia? b. Does the solution have an alkaline reaction towards methyl-orange? towards litmus? For this test, make the methyl-orange and the litmus solutions slightly pink with acid, and divide each solution into two parts. To one part of each, add some of the amine solution; to the second part, add am- monium hydroxide solution. What do you conclude from the similarity in behavior? c. Add some of the amine solution to a drop of copper sulphate solution, then, to a drop of aluminum sulphate solution. Repeat these tests, using ammonium hydroxide in place of the amine. Is there any similarity in behavior? Explain these reactions. 90 COMPOUNDS CONTAINING NITROGEN [§ 53 52. Methylammonium Chloride. After making these tests with the water solution, add dilute, pure hydrochloric acid to the cold amine solution until the liquid has a slight acid reaction. When the hydrochloric acid solution has been evaporated to dryness on a water-bath, the dry crystalline residue should be dissolved in the least possible amount of boiling absolute alco- hol. In this process, use a small flask attached to an air con- denser. A very small residue of ammonium chloride may remain undissolved at this point. If there should be a slight, insoluble residue, filter the solution, and evaporate the filtrate to dryness over a water-bath. a. Heat a small amount of the solid hydrochloride with a solution of sodium hydroxide. Notice the odor. What gas escapes? 6b. Warm some of the salt with calcium oxide in a small, dry test-tube. Is the gas which escapes inflammable? Test the vapor with litmus paper. c. Try the same tests with ammonium chloride in place of methylammonium chloride. Write all equations necessary to emphasize the similarity in the two cases. d. Chlorplatinate. Dissolve some of the salt in a little alco- hol, and add to it a few drops of a 10 per cent. solution of platinic chloride. If no precipitate appears, add a few drops of ether to this solution. “What isformed? [R]. To one drop of a solu- tion of ammonium chloride, add a drop of platinic chloride solution. Compare the precipitates formed in the two cases. e. Isocyanide Reaction for Primary Amines. [H]. Place a few crystals of the hydrochloride in a test-tube with two or three drops of chloroform; add 1 or 2 c.c. of a solution of potassium hydroxide in alcohol, and warm the mixture under the hood. The isocyanide can be recognized in small amounts by its odor. It is poisonous. When you have finished the test, pour the contents of the test-tube into the hood-sink, and rinse out the tube with concentrated hydrochloric acid before you take it to your desk. Is it possible to prepare a salt of hydrogen isocy- anide by heating ammonia with alcohol potash and chloro- form? [RI]. , 53. Triethylammonium Bromide from Diethylamine. In a small flask, mix 5 g. of diethylamine and 8 g. of ethyl bromide. Allow the mixture to stand one day. Connect the flask with a § 55] COMPOUNDS CONTAINING NITROGEN ol reflux-condenser, and heat it for a few minutes upon a water- bath. Cool the reaction product,.collect the crystals upon a filter, and dry them carefully. a. With this salt in place of methylammonium chloride, try the test described under § 52, a-e. 54. Triethylamine. Place the triethylammonium bromide in a small, dry distilling-flask connected with a condenser, and add to it 4 g. of powdered potassium hydroxide. Heat the flask in a bath of boiling water, and collect the amine in a cool receiver. Determine the boiling-point of the amine. a. Dissolve a few drops of triethylamine in water and apply the tests described under § 51 a-c. 55. Tetraethylammonium Bromide. Weigh the triethyl- amine just obtained and mix it with the calculated amount (one gram equivalent) of ethyl bromide. In the course of a day, long needles of tetraethylammonium bromide will separate. a. What is the base to which this salt is related? How would you prepare it from the bromide? Is it an active base? [Rl]. DIVISION 2. POLYATOMIC COMPOUNDS. A eed - ohh » Le a . ee eth . * x CHAPTER X. HALOGEN COMPOUNDS. 56. Ethylene Dibromides. Pour a mixture of 25 g. of abso- lute alcohol and 150 g. of pure concentrated sulphuric acid into a 2-liter flask. Support the flask over a wire gauze, and close it with a stopper having two openings. Through one opening, insert a long-stemmed dropping-funnel; through the other, a doubly-bent delivery-tube leading to the first of a train of three wash-bottles. Charge the first wash-bottle with concentrated sulphuric acid; the second with a strong solution of sodium hy- droxide. The third wash-bottle should contain 40 g. of bromine, covered with a layer of water, and should be placed in a vessel of cold water. Heat the flask cautiously until a regular evolution of gas begins; then, through the dropping-funnel, introduce a mixture of one part of alcohol and two parts of concentrated sulphuric acid. This mixture should be added fast enough to furnish a constant stream of gas; at the same time, violent foaming of the charge should be avoided. When the bromine has changed completely into a transparent, almost colorless liquid, transfer the contents of the absorption bottle to a separatory-funnel, and wash the heavy oil first with a dilute solution of sodium hy- droxide, and then with water. Why? Separate the oil, and dry it with calcium chloride for several hours. Distill it, and preserve it for the preparation of glycol. (Cf. § 59.) Note 6.— A mixture of 50 c.c. of phosphoric acid (sp. gr. 1.7) and 25 c.c. of alcohol may be substituted for the sulphuric acid and alcohol. If alcohol is run into this mixture, heated to about 200°, a constant stream of ethylene will be obtained without the foaming so objectionable when sulphuric acid is employed. ~~ 57. Chloroform. Select a 2-liter flask and fit it with a stopper which has two openings. Through one of the openings insert a bent tube which serves to connect the flask with a con- 55 56 POLYATOMIC COMPOUNDS [§ 57 denser; through the second, introduce a tube long enough to reach to the bottom of the flask, and arranged so that steam may be conducted through it. The tube which reaches to the bottom of the flask must be wide in order to avoid stoppage; a straight calcium chloride tube, or a dropping-tube, will answer. To generate a current of steam, use a 1-liter flask * with a stopper which has two openings, one for an exit tube, and the other for a glass tube, two or three feet long, which serves as a safety-valve. Place the contents of two half-pound boxes of bleaching-powder and 700 c.c. of water in the 2-liter flask. Slowly add a mixture of 25 c.c. of acetone and 50 ¢.c. of water; shake the flask frequently during the addition, and cool it at once if the mixture becomes decidedly warm. Finally, support the flask upon a tripod covered by a piece of wire gauze, and Fig. 16. Steam Distillation. connect it on the one side with the condenser and on the other side with the steam generator. When these connections have been’made, heat the contents of the 2-liter flask until the liquid in it is near the boiling- point, pass a rapid current of steam into the flask, and drive’ the chloroform into the condenser. Collect all of the dis- tillate until you can see no more globules of oil in the liquid as it drops from the end of the condenser. To purify the chloroform, shake it several times in a separa- tory-funnel with a saturated solution of salt. Why? Dry it * A tin ether can may be used in place of a glass flask. § 58] POLYATOMIC COMPOUNDS o7 with fused calcium chloride, and distill it. At what temperature. does pure chloroform boil? [R]. What yield of chloroform have you obtained? a. Try to burn a little of the chloroform. 6. Warm two or three drops of chloroform with a crystal of potassium dichromate and a small amount of concentrated sulphuric acid. Observe the odor of the vapors which escape. What changes take place in moist chloroform when it is exposed to air and light? [RI]. c. Isonitrile Reaction. [H]. Warm one drop of water solu- tion of aniline with a drop of chloroform and a little alcoholic potash. Perform the experiment under the hood; empty the liquid into the sink under the hood, and wash the test-tube with concentrated hydrochloric acid before you take it to your desk. To what class of amines does aniline belong? Cf. § 51, Methylamine. d. What substances would be produced by sean chloroform with alcoholic potash? e. Add a small crystal of iodine to some Biloretcrn f. What methods are employed to prepare pure chloroform for use as an anesthetic? _j 68. Iodoform. Put into a small flask 10 g. of anhydrous sodium carbonate, and dissolve it in 60 c.c. of warm water. Add 8 e.c. of alcohol to this solution, immerse the flask in a water-bath, and heat the liquid to a temperature between 70° and 80°; then add gradually 6 g. of powdered iodine. If the solution has a brown color when it has been heated for a few minutes, add a solution of sodium carbonate, drop by drop, until the brown color just disappears. Cool the liquid, collect the iodoform upon a small filter, and wash it with water. When the solid has drained, recrystallize it from alcohol as follows. After sufficient alcohol has been used to dissolve all of the yellow precipitate, filter the hot solution rapidly through a small paper, which will remove insoluble impurities, chiefly unchanged sodium carbonate; and add water to the filtrate until the iodoform is completely precipitated as a yellow crystalline deposit. Cool the mixture, and collect the precipitate upon a small filter. When the recrystallized iodoform has been dried, preferably upon a small piece of porous plate, determine its melting-point. CHAPTER XI. POLYATOMIC ALCOHOLS AND DIKETONES. 59. Ethylene Glycol. In a flask connected with a reflux- condenser, heat 40 g. of ethylene dibromide with 28 g. of an- hydrous potassium carbonate and 250 c.c. of water, until the ethylene dibromide has disappeared. This operation will require some 10-12 hours. To prevent “bumping,” place in the flask several long pine splinters. When the oily dibromide has dis- appeared, remove the water by evaporation. Owing to the volatility of the glycol with steam, there will be less loss of glycol if the solution is concentrated under diminished pressure. Two distilling-flasks should be connected air-tight by means of rubber stoppers. Through the stopper of the distilling- flask proper, insert a glass tube drawn out to a wide capillary. The tip of this cap- illary must nearly touch the : , bottom of the flask; and at all Fig. 17. Distillation in vacuo. times during the distillation, it should dip below the surface of the liquid. A piece of rubber tubing and a screw-clamp at- tached to the upper end of the glass tube will make it possible to regulate the amount of air admitted. The constant forma- tion of air bubbles at the lower end of the capillary will pre- vent the “bumping” of the boiling liquid. When it is desirable to know the temperature at which a given substance is distill- ing, a thermometer may be placed inside this glass tube with its bulb resting on the shoulders where the capillary begins, and with its upper end just below the clamp, so that by removing 08 - § 60] POLYATOMIC ALCOHOLS 59 the clamp and the rubber tube, the thermometer may be taken out easily. The flask which serves as a receiver, may be cooled if desired. In some cases it is necessary to insert a short condenser be- tween the two flasks to insure sufficient cooling. A filter-pump will give the desired diminution of pressure. When the pressure under which a substance is distilling is to be determined, a manometer (cf. illustration) should be inserted between the re- ceiving flask and the pump.* In the preparation of glycol, since only the solvent is distilling, no thermometer or manom- eter will be needed. When most of the water has distilled and a considerable amount of salt has separated, treat the residue with alcohol to extract the glycol from the crystals of potassium bromide. When the alcohol has been removed by distillation in vacuo, distill the residual glycol at atmospheric pressure. The fraction which boils between 170°-200° will be practically pure glycol. About 4-5 g. will be obtained. The boiling-point of pure glycol is 197.5°. a. ‘What would the theoretical amount of glycol be? How . do you account for this loss? Are any other products formed? What would be the chief product if ethylene dibromide were heated with alcoholic potash? How could you verify your conclusions experimentally? Try your method. b. Treat a little glycol with a piece of metallic sodium. Ex- plain your result. c. Taste a drop of glycol. d. Glycol is a diprimary alcohol. What are its oxidation products? e. What is ethylene oxide? Would you call it an ether? Is the method by which ethylene oxide is usually made similar to any method used to prepare dimethyl ether? 60. The Glycol Ester of Benzoic Acid. In a test-tube, mix 2 drops of glycol, 0.2 c.c. of benzoyl chloride, and 5 c.c. of a 10 per cent. solution of sodium hydroxide. Close the test-tube and shake it for several minutes. After adding 10 c.c. of water, shake the tube again, and collect the precipitate upon a filter. Wash this precipitate, dissolve it in about 25 c.c. of dilute alco- hol (1: 1), and filter the hot solution to remove any suspended * Concerning special forms of apparatus used in fractional distillation under diminished pressure, consult reference books. 60 POLYATOMIG ALCOHOLS [§ 61 particles. Collect the precipitate which forms in the cold solu- tion, wash it with 5 c.c. of dilute alcohol (1:1), dry it, and determine its melting-point. It should melt at 70°-71°. Cf. §§ 11, 12, 40 6, Schotten-Baumann’s reaction. ‘\ 61. Glycerol. a. Add two or three drops of a dilute solution of copper sulphate to a solution of glycerol. Make this solution slightly alkaline by adding a solution of sodium hydroxide. Does a precipitate form? How do you explain the sudden change in color? Add a solution of sodium hydroxide to a dilute solution of copper sulphate containing no glycerol. What difference do you observe? b. Glycerol Ester of Benzoic Acid. Dissolve 4 drops of gly- cerol in 10 c.c. of a 10 per cent. solution of sodium hydroxide contained in a small flask, and add 1 c.c. of benzoyl chloride. Close the flask, and shake it vigorously for several minutes, until a curdy precipitate has formed. It may be necessary to cool the flask from time to time. Add 10 c.c. of water and shake the flask again for a few seconds. Collect the precipitate upon a filter, wash it with water, and then with 10 c.c. of dilute acetic acid? Why? Finally, dissolve it in 15 ¢.c. of boiling alcohol (2 parts alcohol to 1 part water), filter the solution, cool the filtrate, and shake it until the ester is precipitated. Collect the precipitate upon a filter, wash it with 8 c.c. of dilute alcohol (2: 1), dry it, and determine the melting-point. The pure ester melts at 70°-72°. Cf. § 11, Ethyl Alcohol; § 60, Glycol Ester. c. What are the chief constituents of the fats? In what re- spects are they related chemically to the ester of benzoic acid made in b? How is glycerol obtained from the fats? What is lipase, and how does it act in decomposing and in synthe- sizing fats? d. How is ‘“‘notroglycerine” made? Why is the name “‘nitro- glycerine” chemically a misnomer? e. Acrolein from Glycerol.* Put 1g. of glycerol and 0.1 g. of phosphoric acid (sp. gr. 1.7) in a dry test-tube. Close the tube * Note 7.— Powdered fused potassium acid sulphate may be substituted for phosphoric acid; it is objectionable because of the violent foaming of the mixture which it causes. The method given above was proposed by Nef, Ann. 335, 221 (note). § 63] POLYATOMIG ALCOHOLS 61 with a stopper which has a bent delivery tube some 20 cm. long. The end of this tube should dip beneath the surface of 2 c.c. of water in a small test-tube. Heat the glycerol for a few minutes at a temperature of about 240°. Filter the water solution, and apply the following reagents: — Fehling’s solution; ammoniacal silver nitrate; Schiff’s reagent. _ a-Diketone Derivatives. 62. Nickel Salt of Dimethylglyoxime. Put one drop of a solution of nickel nitrate or chloride (10 per cent.) in a large test-tube; fill the tube with distilled water, and mix the liquids thoroughly. Pour one drop of this solution upon a few crystals of dimethylglyoxime, and make this mixture faintly alkaline by adding a little very dilute ammonium hydroxide. The red substance which forms is a nickel salt of dimethylglyoxime, CsHisN.O,Ni. This reaction furnishes a most delicate test for the presence of a nickel salt. It may be used to detect nickel in the presence of a large amount of cobalt; e.g., in commercial cobalt salts. 6-Diketones. 63. Acetylacetone. a. To a dilute solution of acetylacetone in water, add a drop or two of a dilute solution of ferric chloride. Explain the change which occurs. b. To a solution containing 1 g. of copper acetate in 25 c.c. of water, add 0.5 g. of acetylacetone. A blue copper salt of acetylacetone, almost insoluble in water, will separate readily. When the mixture has been shaken until there is no further in- crease in the volume of precipitate, collect the copper salt upon a filter, wash it with water, and dry it. Dissolve the dry salt in some boiling chloroform. Add hot alcohol until a precipi- tate commences to form and allow the salt to crystallize slowly from this solvent. Collect the crystals, wash them with alcohol, and dry them. The melting-point is 230°. c. Heat some dry crystals of the copper salt in a dry test- tube. If heat is applied gently, a green vapor will form, and the salt will sublime and deposit in bright blue needles. If the heat is too great, copper will be deposited. CHAPTER XII. DIBASIC ACIDS. 64, Oxalic Acid. Heat 1g. of dry sodium formate in a small test-tube. When the salt melts, does it boil, or is a gas evolved as a result of decomposition? Apply a flame to the mouth of the test-tube. Cool the fused mass, dissolve it in water, and add a few drops of a solution of calcium chloride and a little acetic acid. (?) Dissolve some unchanged sodium formate in water, and treat the solution with calcium chloride and acetic acid. Does a precipitate form in this case also? Explain your observations. a. Calcium Salt. Neutralize a solution of oxalic acid by means of ammonium hydroxide. Add a solution of calcium chloride. Is the precipitate soluble in acetic acid? What use is made of this salt in detecting small amounts of calcium, and in estimating calcium quantitatively? What other salts of cal- cium are soluble with difficulty in acetic acid? b. Heat a few crystals of oxalic acid, or an oxalate, with some concentrated sulphuric acid. What change occurs? What gases are evolved? Make appropriate tests for each gas. 65. Complex Oxalate Ions. a. Make a 10 per cent. solution of ammonium ferric sulphate, of potassium ferricoxalate, and of potassium ferricyanide. Test small samples of each solution with sodium hydroxide. Which solutions yield precipitates? Explain. b. Pour 5 c.c. of each of the three solutions into separate test-tubes. Place the tubes side by side, and add to each 3 drops of a 10 per cent. solution of potassium thiocyanate. Un- der these conditions, this reagent serves as a test for ferric ions in the case of ammonium ferric sulphate only. The complex ferricoxalate ion is slightly dissociated (cf. a), but has a rather large ‘‘stability constant.” Fe (C2O4)3"”” << Fett + 3 C.0."". This can be demonstrated experimentally as follows: — - 62 § 66] DIBASIC ACIDS 63 a. To 5 c.c. of potassium ferricoxalate solution, add three drops of the potassium sulphocyanate solution and several drops of dilute hydrochloric acid. Explain the appearance of the red color. To 5c.c. of the ferricoxalate solution, add three drops of potas- sium sulphocyanate, and a little calcium chloride. How do you explain the appearance of the red color? B. To 5c.c. of the ferricoxalate solution, add 1 c.c. of calcium chloride solution (10 per cent.). Calcium oxalate is precipitated. To 5 c.c. of ferricoxalate solution, add a small piece of solid ferric chloride about the size of a pea. After it has dissolved, add 1 c.c. of the calcium chloride solution. Is any calcium oxalate precipitated? Explain the difference in behavior in these two cases. c. Interpret these results (a and b) in terms of the law of mass action and of chemical equilibrium as applied to the dissociation of the complex ferricoxalate ion. What are double salts, and how are they distinguished from salts of complex acids? How would you classify the three iron salts used in a? 66. Oxalic Acid as a Reducing Agent. a. Mix a crystal of oxalic acid, or an oxalate, with some pow- dered manganese dioxide and a little dilute sulphuric acid. What gas is evolved? Corroborate your conclusion by an appropriate test. b. Add a few drops of a dilute solution of potassium perman- ganate to a warm solution of oxalic acid containing some dilute sulphuric acid. By equations, represent the reaction involved in the change. c. Action of Light in Accelerating Reduction. Make asolu- tion of mercuric chloride containing 0.5 g.in 10 .c.c. of water. Pre- pare a second solution containing 0.8 g. of ammonium oxalate in 20 c.c. of water. Mix these two solutions, and divide the mixed solution, placing 15 ¢.c. in each of two test-tubes. Put one of these tubes in the sunlight, and the other in a dark cupboard of the desk. In the course of a few minutes, the tube in the light will become turbid; and, after a short time, a white precipitate will form. What is it? Represent the changes by equations. The tube in the dark will show no change even after several days. How could this reaction be employed to measure the relative in- tensities of light from different sources? In the case of the 64 DIBASIC ACIDS [$ 67 oxalates of iron, how is this principle put to practical use in photography? 67. Malonic Acid. Place 20 g. of monochloracetic acid in a porcelain dish containing 40 c.c. of water. Neutralize the acid by adding the calculated amount of sodium acid carbonate. Heat the mixture to 50° or 60° until effervescence ceases; then add 16 g. of powdered potassium cyanide. Potassium cyanide must be handled with great care. This operation must be car- ried out under the hood. Precautions must be taken not to breathe the vapors which escape; they may contain prussic acid and, if so, are very poisonous. After adding the cyanide, stir the mixture, and apply a gentle heat until the reaction is complete. After heating the solution for half an hour, add a solution of sodium hydroxide containing 16 g. of hydroxide in 40 c.c. of water. Boil the alkaline solution until ammonia ceases to be evolved. Add enough water to replace that which passes away by evaporation. Finally, neutralize the solution by adding slowly that amount of dilute hydrochloric acid which contains 7 g. of hydrogen chloride. How can this value be calculated? To precipitate the malonic acid, add a solution of calcium chloride (30 g.). Filter the calcium malonate, wash it with a little cold water, and dry it at 100° until the weight is practically constant. To obtain malonic acid, treat a weighed quantity of the dry calcium salt with a strong solution of oxalic acid containing the calculated amount of oxalic acid. After warming the mixture for a short time, filter it, and evaporate the filtrate over a water- bath. a. Determine the melting-point of the malonic acid which you have made. b. Heat some malonic acid in a test-tube. What gas is evolved? What remains in the tube? c. In a distilling-flask with a long neck, heat 1 g. of ethyl malonic acid. What gas is evolved? When the fused acid has been heated (160°-170°) until gas evolution has ceased, distill the remaining liquid, and observe the boiling-point. By appro- priate tests, determine what this substance is. d. How can the esters of malonic acid be prepared? What use is made of malonic ethyl ester in the synthesis of acids of the acetic acid series? a § 68] DIBASIG ACIDS 65 68. Fumaric Acid from Maleic Acid. Rearrangement of Stereoisomers. Dissolve 0.4 g. of maleic acid in 1 c.c.of water, and add a drop or two of bromine to the solution. Divide it into two parts. Place one part in the dark and the other in direct sunlight. In the course of a few minutes, the tube placed in the light will be found to contain a solution turbid with sus- pended fumaric acid. In the dark, even after many hours, no fumaric acid will separate. a. What is maleic anhydride? Does fumaric acid yield an anhydride? [RI]. | b. What explanation is offered to account for these two isomers? How are their space formule chosen? c. How can fumaric acid be converted into maleic acid? d. Add a few drops of an alkaline solution of potassium per- manganate to a solution of maleic acid. (?) CHAPTER XIII. CYANOGEN AND RELATED COMPOUNDS. 69. Cyanogen, Dicyanogen. Heat a small quantity of mer- curic cyanide in a dry test-tube, and kindle the gas which escapes from the tube. What relation does cyanogen bear to oxalic acid? [RI]. 70. Salts of Hydrocyanic Acid or Prussic Acid. a. Mercuric Cyanide. Dissolve a little mercuric cyanide in water, and add it to a solution of silver nitrate. Try the same test, using potassium cyanide instead of mercuric cyanide. Explain your observations. b. Potassium Ferrocyanide. Dissolve 3.5 g. of ferrous sul- phate in 50 c.c. of water. Add 5 g. of potassium cyanide, and boil the solution for a short time. Filter the solution, and evaporate the filtrate on a water-bath until the salt commences to crystallize. When the salt has crystallized from the cold solution, collect it, and test it. (?) c. How would you convert potassium ferrocyanide into potas- sium ferricyanide? How is potassium cyanide made from po- tassium ferrocyanide? What is the technical process employed in the making of potassium ferrocyanide? How is Prussian blue made? d. How are alkyl cyanides and alkyl isocyanides related to prussic acid? When they are hydrolyzed in the presence of dilute mineral acids, what products do they yield? In what respects does the behavior of these alkyl derivatives differ from that which would naturally be suggested for them by analogy through a study of the hydrolysis of such compounds as acetic ethyl ester, ethyl nitrite, and ethyl sulphate? From the view- point of structure chemistry, and in the language of structural formule, can you propose any hypothesis to account for this divergence? /-71. Cyanic Acid and the Cyanates. Heat a strong solution ‘of potassium cyanate (not cyanide) with a little sodium hydrox- 66 et § 75] CYANOGEN AND RELATED COMPOUNDS 67 ide. Test the vapors with a piece of neutral litmus paper, and notice the odor. Add acid to the remaining solution. What gas is evolved? a. What relation does cyanic acid bear to carbonic acid? Can you illustrate this relation by appropriate graphic formulx? What compound bears a similar relation to acetic acid? How can potassium cyanide be converted into potassium cyanate? 72. Methyl Isocyanate. Make a dry mixture of potassium cyanate and sodium methyl sulphate, and heat it in a dry test- tube. Observe the odor. What products would be obtained by the hydrolysis of methyl isocyanate? (Wirtz method of making primary amines). Cf. § 70, d. 73. Cyanic Acid from Cyanuric Acid. In a small distilling- flask with a long side tube, place several grams of cyanuric acid, previously dehydrated in a beaker upon a water-bath. Dip the side tube of the flask into a long test-tube surrounded by a freezing-mixture, and heat the bulb until the cyanuric acid has almost disappeared. A colorless liquid will be obtained in the test-tube. Notice the odor of this liquid. Test a drop of it with moist litmus paper. When the liquid becomes warm by standing at room temperature, it will suddenly polymerize with a decrepitating sound, and will change to a mixture of cyanuric acid and cyamelid. [R]. Thiocyanic Acid and Isothiocyanic Acid. 74. Ammonium Thiocyanate. Mix 3 c.c. of carbon disul- phide with 15 c.c. of concentrated ammonia water, and add to the mixture 15 ¢.c. of alcohol. After two days, evaporate the solution to dryness over a water-bath. Extract the thiocyanate from the residue by means of hot alcohol. Filter the solution, and allow the salt to crystallize from the alcohol. Dry the salt upon a piece of porous plate, and make tests to show that it is a thiocyanate. 75. Methyl Thiocyanate. Dimethyl Sulphate as an Alkyl- ating Agent. [H]. Dissolve 20 g. of potassium thiocyanate in 10 c.c. of water. To the cold mixture, add, in two portions, 26 g. of dimethyl sulphate. Dimethyl sulphate is extremely poisonous and has no odor. Exercise great care in working with it. Shake the mixture thoroughly and cool it if necessary. After the solution has been heated 15 minutes upon a water- bath, and has been shaken repeatedly during this time, pour the 68 CYANOGEN AND RELATED COMPOUNDS [§ 76 liquid into a separatory-funnel, and remove the ester which will accumulate as a lighter layer. Dry it with calcium chloride, and distill it. The yield should be about 10g. The ester thus obtained will boil between 130°-133°. a. What evidence is there to show that a formula in which the methyl group is linked to sulphur represents the chemical behavior of this ester in a satisfactory manner? 76. Methyl Mustard-Oil. (Hofmann’s reaction.) Place a few crystals of methylammonium chloride in a test-tube, and pour upon them several drops of alcohol, 1 drop of carbon disulphide, and 1 or 2 drops of a strong solution of potassium hydroxide. After a few seconds, add a little water and a slight excess of a dilute solution of silver nitrate. When the solution is warmed until it boils, the odor of the mustard-oil will become pronounced. What are the intermediate products in this reaction? Explain their conversion into methyl mustard-oil. a. What class of amines may be used in making mustard-oils by this method? b. What experimental evidence [R] can you mention to justify the linking of the alkyl groups to nitrogen in the graphic for- mule assigned to mustard-oils? Cf. §72, Methyl Isocyanate. as 4 CHAPTER XIV. UREA AND UREIDS. 77. Urea. (Wohler’s Synthesis.) Mix a solution of 10 g. of potassium cyanate with a solution of 20 g. of ammonium sul- phate in 25 g. of water; place the mixture in a porcelain dish, and evaporate it to dryness over a water-bath. Powder the dry residue, and place it in a small, dry flask connected with a tube which serves as an air-condenser. Add 15 c.c. of absolute alcohol, and heat the flask on a water-bath until the alcohol boils. Pour the hot alcohol through a small filter, leaving the residue in the flask. After repeating this treatment with alcohol three times, combine the filtrates, place them in an evaporating dish, and evaporate them to dryness. Determine the melting- point of the dry crystals. What is the melting-point of urea? 78. Urea from Phosgene. Pour 15 ..c. of ammonia water (sp. gr. 0.96) into a small flask, and add to it slowly 10 c.c. of a 20 per cent. solution of phosgene in toluene. [H]. Shake the flask and cool it if necessary. The solution must react alkaline when all of the phosgene has been added. Evaporate the solu- tion, and extract the urea as described in § 77. These tests are to be performed either with § 77 or with § 78. a. Boil a little urea with a strong solution of sodium hydroxide. What gas is evolved? Acidify the alkaline solution by adding hydrochloric acid, drop by drop. What gas is liberated? How do you explain these changes? In what respects does urea re- semble acetamide? How can you express the relation which it bears to ammonia? to carbonic acid? 6b. Make a strong solution of urea, about 1 c.c., and add some pure concentrated nitric acid to it. Whatisformed? How is it possible to obtain urea from this substance? How will a solu- tion of ammonia in water react with nitric acid? When you take this fact into consideration, what is the probable action of nitric acid upon the urea in water solution? c. Add bromine to a solution of sodium hydroxide until the solution has a deep-yellow color (not red). Fill a test-tube with 69 70 UREA AND UREIDS [$ 80 this solution, and invert it in a dish containing some of the same solution. Put 0.5 g. of urea under the test-tube. What gas is formed? How is this method employed to estimate urea quan- titatively? How would the same reagent act upon ammonia? d. Describe one method by which urea could be made syn- thetically if you had only carbon, oxygen, chlorine, nitrogen, and hydrogen to begin with. Write all equations necessary to illustrate the experimental steps. e. What is the significance of the terms ureids and diureids? 79. Biuret and Cyanuric Acid from Urea. Heat one gram of urea in a test-tube until the substance melts and evolves a gas. Notice the odor of the gas, and test it with moist neutral litmus paper. When the evolution of gas has almost ceased, and the fused mass has become thick, cool the tube, and digest the residue with 3 c.c. of cold water. a. Biuret will dissolve, and may be detected by the addition of a few drops of a solution of potassium hydroxide and one or two drops of a 10 per cent. solution of copper sulphate. Violet- red copper biuret will be produced. This is one of the most delicate tests for urea. In what sense is biuret related to a ureid? b. Cyanuric acid forms the chief product in the tube. After washing the residue once more with 5 c.c. of cold water, dissolve the remaining solid in a few cubic centimeters of boiling water, cool the solution, and add a cubic centimeter of an ammoniacal solution of copper sulphate. Copper cyanurate will separate as a violet crystalline powder. 80. Murexid. Mix 0.5 g. of uric acid with one cubic centi- meter of concentrated nitric acid (sp. gr. 1.4), place the mix- ture in a porcelain dish, and evaporate the solution nearly to dryness. Cautiously add a dilute solution of ammonia. The ammonium salt of purpuric acid (murexid test) will be formed as a purple-red dye. Try the same reaction, substituting caffein for uric acid. Is a similar product formed in this case? CHAPTER XV. POLYATOMIC COMPOUNDS WITH MIXED FUNCTIONS. 81. Monochlor Acetic Acid. Caution: —Do not get this acid on your hands; it produces severe burns. Pour 40 g. of glacial acetic acid into a flask containing 6 g. of red phosphorus. Through the stopper of the flask, insert a delivery-tube and the end of a reflux-condenser. When the flask has been heated in a bath of boiling water, conduct a rapid current of dry chlorine gas into the acid. The absorption of chlorine will take place quite rapidly if the operation is performed in the direct sunlight. If it is impossible to arrange the apparatus so that the direct sunlight can fall upon it, the same result may be brought about somewhat more slowly if a mirror is used to reflect the sunlight upon the flask. The reaction will be complete when a portion of the chlorinated product, placed in a test-tube, solidi- fies on being cooled with ice. Transfer the crude product to a distilling-flask, and distill it. Allow the vapors to pass through a long ‘‘air condenser,” and collect two fractions. The portion which distills between 150° and 200° will be chiefly monochlor acetic acid. This fraction will crystallize when it has been cooled in a beaker surrounded by ice. Transfer the crystals to a Biichner funnel; and, with the aid of a pump, separate the liquid from the crystals as rapidly as possible. The monochloride may fuse if suction is applied too long. A second fraction, boiling between 150° and 200°, may be obtained by distilling the liquid filtered from the crystals. The crystals collected in this way should be distilled again. About 25 g. of monochlor acetic acid will be obtained. The boiling-point of the acid is about 186°. a. After finding an appropriate solvent, recrystallize a portion of the acid. Determine the melting-point of the pure, dry substance. b. Dissolve some of the recrystallized acid in a little water. To one portion of this solution, add a solution of silver nitrate. ; 71 72 COMPOUNDS WITH MIXED FUNCTIONS [§ 84 Is any silver chloride formed? To a second portion of the solu- tion add enough sodium carbonate to neutralize the acid. Boil the solution for a few minutes. Add some dilute nitric acid, and then some silver nitrate. What are the products formed by boiling monochlor acetic acid with dilute alkalies? c. Why is phosphorus used in the chlorination of acetic acid? What substances may be used in place of phosphorus? What other organic compounds are formed during the preparation of monochlor acetic acid? Alcohol Acids. 82. Lactic Acid. Distill 5 ¢.c. of lactic acid with 15 c.c. of 30 per cent. sulphuric acid at 130°. Collect the distillate in a cold receiver, and without applying heat test one portion for acetaldehyde by means of an ammoniacal solution of silver nitrate; test another portion for formic acid, by the addition of mercuric chloride and a solution of sodium acetate. Explain the decomposition. a. What relation does lactic acid bear to propionic acid? 6b. What is sarcolactic acid? How does it differ from the lactic acid obtained from sour milk? c. How is the theory of the asymmetric carbon atom em- ployed in explaining the isomerism of the lactic acids? 83. $-Hydroxybutyric Acid. a. To a dilute solution of 6-hydroxybutyric acid, add a few drops of a 5 per cent. solution of ferrous sulphate and several drops of hydrogen peroxide. Cf. §7, Acetoacetic acid. b. What significance does this reaction have in connection with the chemistry of urine? c. What would be found by heating g-hydroxybutyric acid with concentrated sulphuric acid? } d. What are some of the chief differences observed in the chemical behavior of a-, 8-, and y-hydroxyacids? / 84. Tartaric Acid. How is tartaric acid prepared commer- cially? How can it be prepared synthetically? a. Salts. Calcium Tartrate. Make a solution of sodium potassium tartrate. To a cubic centimeter of this solution, add a strong solution of calcium chloride. Collect the white precipi- tate upon a filter-paper, and wash it thoroughly. Place a little of it in a test-tube, and add a strong solution of sodium hy- droxide to it. Prepare the sodium hydroxide from a piece of e a “aN § 87] COMPOUNDS WITH MIXED FUNCTIONS 73 solid hydroxide which has been washed once or twice to remove the superficial layer of sodium carbonate. Heat the clear alka- line solution of calcium tartrate; a precipitate will form. If the sodium hydroxide solution of calcium tartrate is not clear, filter it, and then heat it. This is an important reaction in the quali- tative test for tartaric acid. (?) b. Reduction of the Silver Salt. Place a very small amount of calcium tartrate in a test-tube. Add to it a few drops of an ammoniacal solution of silver nitrate, and warm the solution gently for several minutes. What does this experiment show concerning tartaric acid? No equation can be written. c. Complex Copper Tartrates. ‘T'o a solution of tartaric acid, add several drops of a solution of copper sulphate and make the mixture alkaline by adding sodium hydroxide. What is Feh- ling’s solution? Repeat the experiment, but in place of copper sulphate, use first ferric chloride, then aluminum sulphate. Will sodium hydroxide alone cause precipitates when it is added to pure solutions of these salts? How do you explain these reac- tions? [RI]. 85. Tartar Emetic. Dissolve 5 g. of potassium hydrogen tartrate in 50 c.c. of water. Add 4 g. of antimonious oxide to this solution, and boil the mixture. Filter the solution and allow it to evaporate until crystals form. 86. Diacetyl Derivative of Tartaric Ethyl Ester. Mix 6 g. of acetic anhydride with 4 g. of the diethyl ester of tartaric acid, and add to it 30—40 c.c. of a 10 per cent. solution of sodium hydroxide. Mix these substances intimately by thoroughly shaking them. .When the odor of acetic anhydride has entirely disappeared and a solid has formed, separate the acetyl deriva- tive by filtration. Wash it with water, and dissolve it in the least possible amount of boiling alcohol. Add water to the hot alcohol solution, until it begins to show a slight turbidity; then allow the acetyl compound to crystallize. Determine the melt- ing-point of the acetyl derivative. It should melt at 67°. Ketone Acids. : 87. Acetoacetic Ethyl Ester. Tautomerism. a. Action of Ferric Salts. Add a drop of a dilute solution of ferric chloride to an alcoholic solution of acetoacetic ethyl ester. Cf. § 63, Acetylacetone; § 127, d, Phenol. b. Copper Salt. Shake an ether solution of the ester with an * 74 COMPOUNDS WITH MIXED FUNCTIONS [§ 87 ammoniacal solution of copper sulphate. Collect the green cop- per salt and recrystallize it from alcohol. Cf. § 63, Acetlyacetone. c. How is the sodium salt of acetoacetic ethyl ester prepared? What views are held concerning the constitutional formule of acetoacetic ethyl ester and its salts? What is meant by the phrase “enol form”? What is the meaning of the term tau- tomerism? d. How can acetoacetic acid be made from 6-hydroxybutyric acid? What are the products of decomposition when a solution of acetoacetic acid is warmed? What significance do these facts have in connection with the chemistry of urine? e. How can acetoacetic acid be obtained from its ester? Describe the reactions involved in the “ketonic splitting” and “acid splitting” of alkyl derivatives of acetoacetic ethyl ester. CHAPTER XVI. CARBOHYDRATES. 88. Test for Carbohydrates (Molisch’s Test modified by Mulliken). Treat avery small crystal of cane-sugar (.05 g.) with 2 drops of a 10 per cent. solution of a-naphthol in chloroform. Down the side of the inclined tube containing this mixture, pour 2 c.c. of concentrated sulphuric acid so that it may form a dis- tinct lower layer. If a carbohydrate is present, a purple-red zone will form in the course of a few seconds. After one or two minutes, add 5 c.c. of water. A purple precipitate will result. Try the same test, but in place of cane-sugar use a small piece of starch; of gum ‘arabic: of filter-paper; 3 linen; of d-glucose. No equations need be written. Reactions with Fehling’s Solution. 89. Monosaccharides. a. Tosix drops of a 10 per cent. solution of d-glucose, add ten drops of Fehling’s solution and 3 ¢.c. of water. Boil the solu- tion, and continue to add the d-glucose solution until the blue color is entirely discharged. Note 8.—F¥or the preparation of Fehling’s solution see § 26, 5, Acetaldehyde. Fehling’s solution is usually prepared of such a strength that each cubic centimeter will oxidize 0.005 g. of glu- cose. If 20c.c. of a solution of d-glucose were needed to remove the blue color in 10 ¢.c. of Fehling’s solution, how much d-glucose would there be in 1 c.c. of the sugar solution? 6b. In a similar way, try the action of Fehling’s solution upon solutions of l-arabinose; of l-xylose; of d-mannose; and of d-galactose. If no precipitate separates at once at room tempera- ture, boil each mixture for two minutes. c. Try the action of Fehling’s solution upon a solution of levulose (fruit-sugar). How do solutions of grape-sugar (d-glucose) and of levulose (fruit-sugar) differ in their be- havior towards polarized light? Why is levulose known as d-fructose? 75 76 CARBOHYDRATES [§ 91 90. Disaccharides. a. Test a solution of cane-sugar (sucrose, saccharose) with Fehling’s solution. If necessary, apply heat for two minutes. Result? Add 0.5 ¢.c. of concentrated hydrochloric acid to a solution of 5 g. of cane-sugar in 50 c.c. of water. Heat this solution on a water-bath for one hour; prevent evaporation as much as possible. Neutralize 1 c.c. with sodium carbonate and test it with Fehling’s solution. How do you explain the results? What is invert-sugar? Why is it given this name? Keep the larger portion of the hydrolyzed cane-sugar solution to use in experiment 50. b. Treat solutions of maltose (malt-sugar) and of lactose (milk-sugar) with Fehling’s solution. Result? What important conclusions concerning the constitutional formula of the three disaccharides used above have been drawn from these experi- mental differences? 91. Polysaccharides. a. Starch Solution. Heat 200 c.c. of water to the boines point and remove the flame. Mix 1 g. of starch with a little cold water, and stir it into the hot water. Test a portion of this solution with Fehling’s reagent. Is there any reduction? Boil the mixture one minute. Does this cause any precipitation of cuprous oxide? b. Hydrolysis of Starch. After mixing some of the starch paste with about one-tenth its volume of concentrated hydro- chloric acid, put it in a flask connected with a reflux-condenser, and heat the flask for one hour on a water-bath. Neutralize the acid with sodium carbonate, and test the solution with Fehling’s reagent. How could this process be employed to estimate starch quantitatively? c. With Fehling’s reagent, test a solution of gum arabic; of dextrin; of glycogen; and a piece of moistened cellulose. Record your observations. ds d. Hydrolysis of Cellulose. Dissolve piecesof cellulose (filter- paper) in cold concentrated sulphuric acid by triturating them in a mortar until solution results. Add the acid drop by drop. Pour the solution into water, and boil the acid solu- tion for half an hour. Neutralize the solution with sodium carbonate and test it for hexoses. Does it reduce Fehling’s solution? § 93] . CARBOHYDRATES 77 92. Starch Iodide. To some cold starch solution prepared under ‘‘Polysac- charides, a,’’ add a drop of a very dilute solution of iodine in water containing potassium iodide. Heat the blue solution; then cool it. Try this same test, but in place of starch, use a solution of glucose; of cane-sugar; of dextrin; of gum arabic; and of glycogen. 93. Phenyl Glucosazone. ‘To the remainder of the solution of hydrolyzed cane-sugar (invert-sugar), prepared under ‘‘ Disac- charides, a,’ add 8 g. of sodium acetate and 5 g. of phenyl- hydrazine. Warm this mixture upon a water-bath for 2 hours. Collect the yellow precipitate upon a Biichner funnel, wash it with a little cold acetone, and recrystallize it from the smallest possible amount of boiling 80 per cent. alcohol. Collect the precipitate, dry it upon a piece of porous plate, and determine its melting-point. The recorded melting-point is 205°. a. What products are found by the hydrolysis of cane-sugar? b. How do you explain the fact that only one osazone is found in the experiment above? What significance does this have in the choice of configurations for the hexose sugars? CHAPTER XVII. : AMINO ACIDS. 94. Glycocoll, Glycine, Aminoacetic acid. Pour 50 c.c. of a 40 per cent. formalin solution into a 200-c.c. flask and add 18 g. of ammonium*chloride. Cool this mixture in ice water. Very slowly, and with frequent shaking of the mixture, add a cold solution of 22 g. of 98 per cent. potassium cyanide in 30 c.c. of water. This process should require about 3 hours. During the last hour and a half, drop in also 13 c.c. of glacial acetic acid. Methylene-aminoacetonitrile is formed as a solid, and should be collected upon a filter and dried upon a porous plate. The yield will be about 60 per cent. of the theoretical amount. Cover these crystals with 20 c.c. of cold alcohol previously saturated with hydrochloric acid, and, after an hour, add 100 c.c. of water. Remove the alcohol by distillation, and evaporate the residue to dryness. Recrystallize the product from dilute alcohol. The yield, calculated upon the basis of the methylene- aminoacetonitrile, should be about 80 per cent. a. The Copper Salt. Mix a solution of the glycine salt with some freshly precipitated copper oxide, and evaporate it until the copper salt commences to crystallize. b. Glycine combines with acids, as well as with bases, to form salts. What name is applied to inorganic compounds which function both as bases and as acids; e.g., aluminium hydroxide, zine hydroxide, lead hydroxide? Taking this property of the amino acids into consideration, what constitutional formula has been proposed for glycocoll itself? c. What are leucine, alanine, asparagine? What are poly- peptides and how are they obtained from amino acids? What relation are they supposed to bear to the proteins? What evi- dence is there in support of this view? 78 CHAPTER XVIII. COLLOIDS. 95. I. Suspension Colloids (Suspensoids; Hydrophobic or Lyophobic Colloids). a. Colloidal Ferric Hydroxide. Examine the colloidal solu- tion of ferric hydroxide which has been given you. Does the solution appear to be homogeneous? Note 9.— This solution may be prepared by adding ammonium hydroxide to a fairly dilute solution of ferric chloride until the solution of the ferric salt is just neutralized. Place the solution in a dialyzer, and dialyze it against distilled water for some ten days, until the dissolved salts are eliminated. Do you notice any appreciable change in homogeneity when some of the colloidal solution is diluted with large or small quan- tities of water? Examine a drop of the colloidal solution under an ultramicroscope or a dark ground microscope. What do you observe? b. Influence of the Electric Current. Pour some of the col- loidal solution of ferric hydroxide into a small U-tube having a rather long connecting arm of small diameter; insert platinum electrodes into the arms of the U-tube, and attach the ter- minals of the electrodes with several cells connected in series. When a current is passed, what happens immediately? after several minutes? after an hour? after several hours? What do you conclude from this behavior? c. Precipitation of the Colloid. Effect of Salt Concentra- tion. For the following experiments, it will be necessary to have one or two 5-c.c. pipettes graduated to 0.1 ¢.c., and a 25-c.c. grad- uated cylinder or flask. The salt solutions used here and under d are all molar.* Starting with a M/10 solution of sodium chlor- ide, prepare 10 c.c. of solutions of approximately the following * In all of the experiments which follow, N is used to designate equiv- alent normal solutions; and M, in all cases, to signify molar solutions. 79 80 COLLOIDS [$ 96 concentrations: — 1/20; 1/50; 1/100; 1/200; 1/300 M. Place these solutions in labeled test-tubes arranged in the order of increasing concentration, together with a tube containing 10 c.c. of distilled water for comparison. Drop 0.5 c.c. of the colloidal solution of ferric hydroxide into each tube. In the course of a few minutes, do you observe any change in the appearance of the tubes? Keep these tubes for experiments described later under e. d. Comparison of Precipitates Produced by Various Anions and Cations. With concentrations the same as those used in c, prepare a similar series of five tubes with each of the following salt solutions: —M/10 sodium bromide; M/10 sodium iodide; M/10 sodium phosphate (Na,HPO,); M/10 sodium sulphate. Add to each solution 0.5 c.c. of colloidal ferric hydroxide solution. In a similar way, investigate solutions made by diluting a M/10 solution of sodium chloride; a M/10 solution of calcium chloride; a M/10 solution of barium chloride; a M/10 solution of aluminium chloride. When solutions of the different salts of the same concentrations (e.g., M/100) are compared, do you notice any difference in the precipitating effect produced by anions and by cations of different positive and negative values? e. Heat Effect. Heat some of the tubes in which no pre- cipitates formed. Do not boil the solutions. Does this cause precipitates to form? Reserve other solutions in which no precipitates were produced, and examine them the next day. Have precipitates formed in any of these tubes? What do you conclude regarding the time element in the precipitation of colloids? f. Colloidal Metals and Sulphides. If practical, these ex- periments may be tried with a colloidal solution of silver; of platinum; of one of the metallic sulphides, e.g., arsenious sul- phide. 96. II. Emulsion Colloids (Emulsoids; Hydrophilic or Lyophilic Colloids). a. Swelling and “Solution” of Emulsoids. Examine samples of the following solids: — Egg albumin, gelatine, fibrin, gluten, casein, and starch. Drop a small amount of each of these solids into separate test-tubes, and pour a little water upon each sample. Notice that after a time some of the samples swell. | Now, warm them all, at first slightly, and then until the § 96] COLLOIDS 81 water boils. - Observe that with this treatment others swell, while some apparently go into solution; and that these liquids are then miscible in any proportion with water to give solutions apparently clear. 6. Homogeneity. Examine drops of these solutions under an ultramicroscope. What differences do you notice when you compare the results obtained here with the results obtained with the colloidal solution of ferric hydroxide? c. Effects of Salt. With asolution of egg albumin, prepared by filtering a solution made by treating white of egg with some ten times its volume of water, repeat some of the experiments with the various salt solutions described above under ferric hydroxide. What results have you obtained? How do they differ from the results obtained with the ferric hydroxide solution? d. Nature of Certain Albumin Tests. ‘T'o the solution of egg albumin, add a concentrated (saturated) solution of magnesium sulphate, or of sodium sulphate. How does a solution of ferric chloride, or of dilute acetic acid and potassium ferrocyanide, affect the albumin solution? What is the action of concentrated nitric acid upon it? When these changes are considered, what would you say concerning the nature of some of the ordinary tests for albumin? e. Swelling of Fibrin Produced by Acid. Choose five test- tubes of uniform diameter, and place in them respectively 20 c.c. of N/250, N/230, N/220, N/210, N/200 hydrochloric acid. To this series, add another tube containing 20 c.c. of distilled water. In each tube place 0.2 g. of finely powdered blood-fibrin, care- fully weighed. Shake the tubes occasionally, and inspect them at intervals during a period of 24-48 hours. What changes take place in the appearance of the fibrin? Do the acids of different concentrations affect fibrin in the same way? Is there any relation between swelling and concentration of acid? f. Swelling of Fibrin Produced by Alkali. Prepare a similar series of tubes containing solutions of sodium hydroxide, or of potassium hydroxide, equivalent in concentration to the acid solutions previously employed. Add to each tube 0.2 g. of fibrin as before. How does the swelling in alkaline solution compare with that observed in acid solution of equivalent con- centration, or in distilled water? 82 COLLOIDS [$ 96 g. Influence of Salts upon Swelling Induced by Acids and by Alkalies. Into each of five test-tubes, pour 20 c.c. of N/200 hydrochloric acid; add to these tubes respectively 1, 2, 3, 4, and 5 ¢.c. of a molar solution of sodium chloride, and enough dis- tilled water to make the total volume 25 c.c. For comparison, prepare two other tubes, one containing 20 ¢.c. of N/200 hydro- chloric acid diluted to 25 ¢.c.; and the other, 25 ¢.c. of distilled water. Into each of the seven tubes put 0.2 g. of blood-fibrin carefully weighed. When the tubes have stood for some time, what conclusions do you draw concerning the effect of sodium chloride upon the swelling of fibrin in acid solution? h. Influence of Anions and Cations upon Swelling. Pre- pare two more series of tubes containing 20 c.c. of N/100 hydro- chloric acid as before under g. Here, however, instead of adding different concentrations of the same salt, use the same -con- centrations of different salts, first with dissimilar anions, and then with dissimilar cations. To five of the tubes containing acid, add respectively the same volume of molar solutions of sodium chloride, sodium bromide, sodium sulphate, sodium iodide, sodium phosphate. Arrange these tubes beside the comparison tubes containing pure acid and distilled water. To each of the seven tubes add 0.2 gram of blood-fibrin. Prepare a-second series of seven tubes, and to five of the tubes containing acid, add the same volume of molar solutions of sodium chloride, calcium chloride, barium chloride, magnesium chloride and aluminium chloride. To each of the tubes including the com- parison tubes of pure acid and water, add 0.2 gram of fibrin. Record and compare your results. What are saline cathar- tics? What are saline diuretics? How do they affect colloids? 1. Non-Electrolytes and Swelling. Perform a series of ex- periments with fibrin and N/200 hydrochloric acid; but use osmotically equivalent solutions of ethyl alcohol or methyl alcohol, of glycerol, of urea, in place of the electrolytes em- ployed above. Solutions of the non-electrolytes which have twice the molar concentration of the solutions of electrolytes found active above will be accurate enough. Since the dissoci- ation of the salts in molar solution is less than 90 per cent., the use of double molar solutions would favor the non-electrolytes provided the effect is an osmotic one. What are the results? § 96] COLLOIDS 83 j. The Swelling of Dried Gelatine Plates. Absorption Curves. After carefully weighing plates of dried gelatine, drop one of them into a dish containing 100 c.c. of N/20 hydro- chloric acid, and another into a dish containing 100 c.c. of Fig. 18. N/20 sodium hydroxide. Place one more of these weighed plates in 100 c.c. of distilled water. From time to time, weigh the plates and record the weights. This process should extend over a period of 2-3 days. Plot ab- sorption curves with values cal- culated in percentage of change based upon the original weights of the dried plates as ordinates, and the times as abscisse. | Thefollowing curvestaken from Dr. Martin H. Fischer’s work ‘‘Gidema’’ will serve to il- lustrate the method of plotting such curves. Fig. 18 illustrates the effect of certain acids and alkalies upon gelatine. Fig. 19 illustrates the effect of salts in “ 2» modifying the swelling of gelatine produced by acids and by alkalies. — Gelatine — Fig. 19. Note 10. — The Making of Gelatine Plates. Dissolve one part of the best commercial gelatine (Ne Plus Ultra Gelatine of the 84 COLLOIDS [§ 96 Deutsche Gelatine Fabriken serves the purpose well) in 4 parts of water at a temperature of about 45°. Pour this solution into shallow pans. Allow the gelatine to harden in an ice-chest. With the aid of a sharp knife and a ruler, cut the gelatine into plates of uniform size (2.5 cm. square). Allow the squares to dry upon glass plates in a warm place (30°-40°). This operation will require from 6-10 days. The plates may conveniently be made of such a size that, when dry, they measure about 18 X18 X2.6 mm. They will weigh about 0.8g. Uniform material is essential, if comparisons are to be made from which valid conclusions may be drawn. PART II. AROMATIC COMPOUNDS. DIVISION 1. CARBOCYCLIC COMPOUNDS. DIVISION 2. HETEROCYCLIC COMPOUNDS. SA _ = ~ee tr ; = * ‘| cis = Bot. a. ~ a —* ty . > = ® « all | i ‘ My ay iy ly oe? Po g ci < 5 . } e 2 ae P : i CHAPTER XIX. BENZENE HYDROCARBONS. oe 97. Benzene. a. Treat 2 c.c. of benzene with a few drops of a solution of bromine in carbon tetrachloride. What do you observe? Com- pare ve behavior with that observed in the case of amylene. (Cf. § 6.) b. Shake 2 c.c. of benzene with a dilute solution of potassium permanganate made slightly alkaline by means of sodium car- bonate (von Baeyer’s reagent). Compare this case with the reaction of ethylene and olefine hydrocarbons toward the same reagents. c. Add a few drops of bromine to 10 c.c. of benzene, and pour equal portions of this solution into each of two dry test- tubes. To one tube, add some iron filings. What differences do you observe in the velocity of the action in the two tubes, as shown by the evolution of hydrogen bromide? Is the product formed by the action of one equivalent of bromine upon benzene to be considered as a substitution prod- uct, or as an addition product? (?) d. What is Kekulé’s constitutional formula for benzene? In these reactions, does benzene seem to show the behavior which is so typical of an unsaturated hydrocarbon of the ali- phatic series? 98. Benzene Sulphonic Acid. Pour 3 c.c. of benzene and 10 c.c. of concentrated sulphu- ric acid into a large test-tube; close the tube with a stopper through which a long glass tube, or air-condenser, passes. Shake the tube, and heat it gently until the benzene, which at first floats upon the surface of the acid, has entirely dissolved. Pour a little of this solution into a beaker of water. Does benzene separate when the solution has cooled? Pour the remainder of the solution into about four times its volume of a saturated solution of sodium chloride. Crystals of the sodium salt of ben- 87 88 BENZENE HYDROCARBONS [§ 98 zene sulphonic acid will be precipitated. Collect these crystals on a Biichner funnel; wash them with a little cold water, and dry them. Preserve this salt for a later experiment. (See § 127, c, Phenol.) a. Shake several drops of toluene with one or two cubic centimeters of fuming sulphuric acid, and pour the homogeneous solution into water. Try the same experiment with petroleum ether (benzine). What difference do you observe? Is this a distinctive criterion by which one may judge of the chemical nature of a hydrocarbon; or do the two classes of hydrocarbons, represented by benzene and petroleum ether respectively, re- spond to the action of concentrated sulphuric acid in a similar manner, but with great disparity in velocity? CHAPTER XX. NITROBENZENE AND SOME OF ITS REDUCTION PRODUCTS. “+ 99. Nitrobenzene. Put into a flask 35 c.c. of ordinary con- centrated nitric acid (sp. gr. 1.41), and add to it carefully 40 c.c. of concentrated sulphuric acid. Cool the mixture under the water-tap, and add 25 g. of benzene in five or six portions, and with constant shaking of the mixture. The introduction of the benzene should take about half an hour. Then warm the flask at a temperature of 60° on a water-bath for half an hour, and shake it from time to time. The nitrobenzene should float upon the mixture. Now pour a drop of the contents of the flask into water, and note whether the oil sinks or floats. If the oil is practically free from benzene, it will sink. If the nitration of the benzene has been successful, pour the product into a flask containing about 500 ¢.c. of water. Shake the mixture thoroughly, cool it, and separate the lower layer of nitrobenzene by means of a separatory-funnel. Wash the nitrobenzene with water, and dry it thoroughly with fused calcium chloride. Then distill it, using a condenser with- out a water-jacket. The first cubic centimeter or two will be chiefly benzene and a little water. This should be collected 89 90 NITROBENZENE [§ 102 separately, and should not be allowed to run through the clean condenser-tube. When these impurities have volatilized, the temperature will rise rapidly to the boiling-point of nitrobenzene. At this point, connect the distilling-flask with the condenser- tube, and distill the liquid until the residue in the flask becomes thick and dark brown in color. What is the observed boiling- point? a. Is this a general method for preparing aromatic nitro- compounds? Can any of the aliphatic nitro-compounds be made in a similar way? What commercial value does this reaction have? What nitrating agents are commonly employed in technical work? / 100. Meta-dinitrobenzene. Mix 3 drops of benzene with i c.c. of concentrated nitric acid (sp. gr. 1.4) and 1 c.c. of con- centrated sulphuric acid (sp. gr. 1.84). Boil the mixture gently for one-half minute. Pour the product into 10 c.c. of water, collect the precipitate upon a small filter, and wash it until the washings are colorless. Dissolve the crystals in 8 c.c. of boiling dilute alcohol (equal parts of water and alcohol). Set the tube aside, and allow the solution to cool; long needles of meta-dinitrobenzene will form. Collect these crystals upon a filter, wash them with 5 c.c. of dilute alcohol (1:1); dry them, and determine their melting-point. The recorded melting-point is 90°. Small quantities of benzene may be identified by this reaction. 101. Azoxybenzene. Dissolve 15 g. of nitrobenzene in 125 c.c. of methyl alcohol, and add to it 20 g. of powdered ‘sodium hydroxide. Heat the mixture for two hours upon an actively boiling water-bath. Remove most of the methyl alcohol by distillation, and pour the dark residue into ice water. Azoxybenzene will separate as an oil, which, however, will soon solidify. Collect the solid upon a Biichner funnel, and wash it. After shaking this residue with some warm dilute hydrochloric acid for a few minutes, cool it until it solidifies once more; collect it upon a filter and wash it. To purify this crude azoxy- benzene still further, recrystallize it from warm alcohol (90 per cent.). The melting-point is 36°. 102. Azobenzene.* Pour 125 c.c. of methyl alcohol into a flask (about 1-liter) and add 12.5 g. of nitrobenzene. Connect * Suggested by Dr. H. S. Fry, University of Cincinnati. ae i * _ at © Ms Cea ar § 104] AND ITS REDUCTION PRODUCTS 91 the flask with a reflux-condenser, and add 7.4 g. of powdered magnesium. If the action does not commence at once, a crys- tal of iodine may start it. The vigorous action which fol- lows should be controlled by submerging the flask in cold water. The reaction requires ten or fifteen minutes for com- pletion; the end is reached when the odor of nitrobenzene has disappeared. After removing most of the methyl alcohol by distillation, transfer the residue to an evaporating-dish, and heat it upon a steam bath until it becomes dry. Pulverize the residue and extract the azobenzene with ether, preferably in a Soxhlet apparatus. When the ether is removed, recrystallize the azoben- zene from methyl alcohol. The melting-point is 68°. The yield should be about 95 per cent. of the calculated amount. a. Is azobenzene a ‘‘dye”? Why isit called a chromogen? What is a chromophor group? an auxochrome group? 103. Hydrazobenzene. Dissolve the azo- benzene in boiling alcohol, and add zine dust to it in small portions until the red color is entirely discharged. Filter the hot solution rapidly. To the filtrate, add hot water which contains a little sulphurous acid (?) until the solution becomes slightly turbid; then set it aside, and allow the hydrazobenzene to separate as the solution cools. Collect the precipitate . upon a filter, wash it with water containing sulphurous acid, and dry it. The melting- point is 126°. a. How can hydrazobenzene be changed to azobenzene? to aniline? b. Does hydrazobenzene reduce Fehling’s solution? 104. Benzidine Salts. ‘‘ Benzidine Rearrangement.’ The hydrazobenzene obtained above should be treated with one and a half times its weight of concentrated hydrochloric acid and twice its weight of water, and then boiled gently for a few min- utes. When the acid solution is cooled, benzidine hydrochloride Fig. 21. Soxhlet Extractor. 92 NITROBENZENE [§ 105 will separate. Collect the crystals upon a filter and purify them by recrystallization from water. Add a few drops of sulphuric acid to the filtrate. Benzidine sulphate is soluble with difficulty, and will separate. a. How could you prepare benzidine from its salts? How is benzidine employed in making dyes? _ 6. Does benzidine hydrochloride reduce Fehling’s solution? 105. Aniline. Into a 500-c.c. flask put 15 g. of nitrobenzene and 27 g. of granulated tin, and add, in small portions, 100-150 e.c. of strong hydrochloric acid. Shake the flask frequently. The mixture will become so warm that the reaction must be controlled by occasionally cooling the flask. The reaction will be complete when the odor of nitrobenzene has almost dis- appeared. During the course of the experiment, a white double salt of tin chloride and aniline chloride will usually separate. At the close of the operation, add water enough to dissolve this salt; then pour off the solution, leaving the excess of tin in the flask. Tio remove any unchanged nitrobenzene, cool the solu- tion thoroughly, place it in a separatory-funnel, and extract it two or three times with small portions of ether. This ether extract should be thrown away. What does it contain, and why is the extraction desirable? To the acid solution separated from the ether, add solid caustic soda until the stannic acid and stannous hydroxide which form at first are almost redissolved. Care! If the solu- tion grows very warm, cool it immediately before you add any more sodium hydroxide. Most of the aniline will separate as an oil. It will be safer, however, to add the sodium hydroxide until the solution reacts strongly alkaline towards litmus. In some cases, the oil may not separate, but may remain com- pletely dissolved. Arrange an apparatus like the one described under chloroform, and distill the aniline in a current of steam until no more oil drops pass over. Extract the distillate with ether, and dry the ether solution with solid sodium-hydroxide; then filter it, distill the ether from a water-bath, and fractionate the aniline in a small distilling-bulb. The condenser needs no jacket. What yield have you obtained? a. What relation does aniline bear to benzene? to ammonia? to methylamine? § 107] AND ITS REDUCTION PRODUCTS 93 b. Shake a drop of pure aniline with a few cubic centimeters of pure distilled water (ammonia free), and test the clear solution with a piece of neutral litmus paper. What is the reaction? c. Add some of this solution to a solution of ferric chloride; of zinc chloride; of aluminium chloride. In view of the reaction shown in b, how do you account for the observations which you have made with these salt solutions? d. Dissolve a drop of aniline in the least possible amount of dilute hydrochloric acid. Why does aniline dissolve easily in acids, while it is soluble with difficulty in water? Add a few drops of this acid solution to a solution of hydrochlorplatinic acid. What is the formula of the compound which is pre- cipitated? [R]. Does ammonium chloride react in a similar way with hydrochlorplatinic acid? (Cf. § 52, Methylammonium Chloride.) 106. Phenylammonium Chloride, Aniline Hydrochloride. Pour 15 g. of freshly distilled aniline into a mortar, and add to it a little more than one equivalent of pure hydrochloric acid in the form of concentrated acid (sp. gr. 1.18). When the two © substances have been thoroughly mixed by rubbing them to- gether with a pestle, cool the product and collect. the salt upon a Buchner funnel. Drain the salt thoroughly upon a Biichner funnel by applying suction with a filter-pump, and dry the solid in a beaker upon a water-bath. This salt will be needed for later experiments. Cf. § § 109, 112. : 107. Hydrolysis of Aromatic Amine Salts. a. Test a solution of pure aniline hydrochloride in water with Congo red paper, then with neutral litmus paper. Explain your results. Are any oil drops of aniline visible in this solution? b. Dissolve about 0.5 g. of para-nitraniline in the smallest possible amount of boiling concentrated hydrochloric acid. Filter the hot solution and cool it under the tap; the hydro- chloride of para-nitraniline will be precipitated. Collect the crystals upon a filter and dry them thoroughly to remove all traces of free hydrogen chloride. Transfer them to a watch- crystal, and moisten them with a few drops of water. How do you explain the change of color? With neutral litmus paper, test the liquid which surrounds the yellow precipitate. Explain your observations. 94 NITROBENZENE, ETC. [§ 108 c. Dissolve a few crystals of diphenylamine in a little alcohol, and pour the solution into water. Add concentrated hydro- chloric acid, a drop at a time, until the diphenylamine dissolves. If water is added to the clear solution, diphenylamine will be precipitated. Explain. d. From the observations which you have just made, what seems to be the influence of nitro groups and of phenyl groups upon the base-forming power of aniline? Is there any generali- zation covering these cases and others of a similar nature? Cf. Appendices D and E. * 108. Acetanilide, Antifebrin. Put 5 g. of aniline and 7 g. glacial acetic acid in a small flask, connect the flask with a reflux-condenser, and heat the flask over a wire gauze. The mixture should boil gently for 4 or 5 hours. At the end of this time, pour the product into 200 c.c. of cold water. Filter the mixture, wash the crystals with dilute hydro- chloric acid, and recrystallize the acetanilide from hot water. If the crystals are colored, add a small amount of animal char- coal to remove the color during the process of recrystallization. Dry some of the crystals and determine the melting-point. Acetanilide is known as antifebrin. a. Heat some of the crystals with a strong solution of sodium hydroxide. What is formed? Boil a few crystals with dilute sulphuric acid (1:1). Notice the odor of the vapor. (?) | b. How does acetanilide differ from aniline acetate? Is aniline acetate formed in this preparation? What would be obtained by heating ammonium acetate? c. Heat 2 c.c. acetyl chloride with 1 ¢.c. of aniline, and treat the product with water. Separate the crystals and recrystallize the substance from a little boiling water. Compare the melting- point of these crystals with the melting-point of a sample of acetanilide prepared above. d. Warm 1 ¢.c. of acetyl chloride with 1 c.c. of monomethyl- aniline; then heat 1 c.c. of acetyl chloride with 1 c.c. of dimethyl- aniline. Pour each product into water. Is there evidence of chemical change in each case? Are the reactions illustrated in c and d typical of primary, secondary, and tertiary amines in general? CHAPTER XXI. DIAZONIUM SALTS AND DIAZO COMPOUNDS. AZO-DYES. Diazonium Compounds. 109. Benzene Diazonium Chloride (Solid). Make a solution of 5g. of solid aniline hydrochloride in 35 c.c. of absolute alcohol containing a few drops of hydrochloric acid. Cool it until the temperature is about +5°, and add 6 g. of amyl nitrite. This process is called diazotizing. The success of the operation may be determined as follows: — To a drop of the solution, placed upon a water-glass, add a drop of a solution of sodium acetate; a yellow precipitate will indicate an excess of the aniline salt and insufficient nitrite. If this should be the case, add a little more nitrite, and apply the test with acetate again. Finally, sodium acetate should give no yellow precipitate; but, even after long standing, a drop of the solution placed on a water-glass must give a blue color with a little starch solution containing potassium iodide. (?) To promote the separation of the diazonium salt, add a few drops of ether. (?) Collect the precipitate upon a funnel, and wash it with ether. Dry a very small amount of it, and heat it upon a metal spatula. (Explosive!) Dissolve the remainder at once in 50 c.c. of water cooled to +5°. 110. Benzene from a Diazonium Salt. The diazonium chlo- ride solution prepared in the previous experiment should be poured into a cold solution of sodium hydroxide containing 10 g. of sodium hydroxide dissolved in 30 ¢.c. of water. Make an alka- line solution containing 20 g. of stannous chloride (SnChk, 2 H.O), and add it gradually to the former solution. When the resulting mixture is distilled, benzene and water vapor will pass over. About 4 g. of benzene can be separated from the distillate. This method is frequently employed to convert amino-compounds into hydrocarbons; or, expressed in hypothetical terms, “to eliminate amino groups.”’ Alcohol is sometimes employed as a reducing agent in place of stannous chloride. 95 96 DIAZONIUM SALTS [§ 111 Benzene may be identified by its boiling-point, or by con- version into m-dinitrobenzene. (Cf. § 100.) a. What is Sandmeyer’s reaction? b. By the intermediate formation of diazonium salt, how could aniline be changed into phenol? into iodobenzene? into benzonitrile? Diazo Compounds. 111. Para-nitrophenyl-antidiazotate. Dissolve 7 g. of p-nitraniline in 25 ¢.c. of hot dilute hydrochloric acid (1:1); pour this solution upon crushed ice, and add 4 g. of sodium nitrite dissolved in 13 c.c. of water. Some ice should remain at this point. To make sure that sufficient nitrite has been used, apply the test with sodium acetate described in § 109. When enough nitrite has been added, stir the turbid solution until it becomes practically clear, and filter it rapidly through a funnel containing a loose plug of cotton. Test the filtrate to make sure that sufficient nitrite has been used. Dissolve about 20 g. of sodium hydroxide in 200 c.c. of water; and, with the temperature of this solution at 60°, pour the diazonium solution rapidly into it. Golden-yellow crystals of sodium p-nitrophenyl- antidiazotate will separate abundantly when the mixture is thoroughly cooled. Collect the crystals upon a Biichner funnel, and wash them carefully with a little ice-cold water. Dissolve them in 90 per cent. alcohol at a temperature not exceeding 60°. Filter the solution, and allow it to stand until the salt crystallizes. The yield will be about 6g. The corresponding syndiazotate has not been prepared. (Schraube and Schmidt, Ber. 27, 518.) a. Make a dilute water solution (30 ¢.c.) of the sodium anti- diazotate, and pour 5 c.c. of it into an alkaline solution of e-naphthol; of 6-naphthol. b. Acidify 5 c.c. of the solution of the antidiazotate by adding dilute hydrochloric acid until the solution reacts distinctly acid. What does this solution contain? Pour some of this acidulated solution into an alkaline solution of e-naphthol; of 6-naphthol. The alkali must be in excess. c. Acidify 5 c.c. of the original solution of the antidiazotate, but make it distinctly alkaline before you pour it into an alkaline solution of a-naphthol; of 6-naphthol, § 113] AND DIAZO COMPOUNDS. AZO DYES’ 97 d. What are syndiazotates?» What réle do they play in the formation of azo-dyes? How are they changed into anti- diazotates? How are antidiazotates changed into diazonium salts? into syndiazotates? In view of these relations, explain the observations which you have made in performing experi- ments a, b, and c above. Azo Dyes. 112. Benzene Diazonium Chloride Solution. To a mixture of 21.5 c.c. (24 mols) of concentrated hydrochloric acid (sp. gr. 1.18) and 20 c.c. of water, add 10 g. of aniline (1 mol). Put into this solution enough crushed ice to keep the temperature of the solution below 10° during the following operation. Dis- solve 7.7 g. of sodium nitrite in 20 c.c. of water, and add it slowly to the solution of the aniline salt. At the end of this process, called “diazotizing,’ there should be some ice left. A sample of this product placed upon a watch-crystal and treated with an excess of a solution of sodium acetate, should. give no yellow color or precipitate. The appearance of a yellow precipitate or color indicates insufficient nitrite; should this occur, add a little more nitrite solution, and test the diazo solution again. When enough nitrite is present, a drop of the diazonium chloride solution, when brought in contact with starch and potassium iodide, should show the starch-iodide test, if not immediately at least after a short time. In the prepara- tion just described, what is the yellow precipitate formed by the addition of sodium acetate? 113. ‘* Coupling ’’ of Diazo Compounds with Amines and with Phenols. a. With amines. To a water solution of dimethylaniline hydrochloride, add a little of the diazonium chloride solution and a slight excess of sodium acetate solution. Pour some of the diazonium chloride into an alcoholic solution of a-naphthyl- amine and of 6-naphthylamine, and add an excess of sodium acetate. What are the products formed in these reactions? b. Add some of the diazonium chloride solution, first to a solution of naphthionic acid dissolved in an excess of sodium hydroxide, and then to a solution of naphthionic acid in an excess of sodium acetate. c. With phenols. Add some of the diazonium chloride so- lution to solutions of phenol; of resorcinol; of a-naphthol; of 98 DIAZONIUM SALTS [§ 115 6-naphthol. These substances should be employed first in acetic acid or alcohol solution; second, in acetic acid with an excess of sodium acetate; third, in a dilute solution of sodium hydroxide. Explain the reactions in each case. 114. Diazoaminobenzene. Pour one-half of the diazonium chloride solution prepared in § 113 into a beaker cooled by sur- rounding it with ice, and add 6 g. of solid aniline hydrochloride. (Cf. §106.) Make a concentrated solution of sodium acetate containing 23 mols and add it to the solution made above. After an hour or two, collect the precipitate upon a funnel connected with a filter-flask and pump; drain it thoroughly and wash it with water. When it has been dried upon a porous plate, recrystallize it from low-boiling ligroine or gasoline. A flask connected with a reflux-condenser should be employed in this process. Diazoaminobenzene should form golden-yellow erystals, which should melt at 98°. The yield should be about 70 per cent. of the amount calculated. a. Dissolve a small amount of diazoaminobenzene in alcohol, and add to it an alcoholic solution of silver nitrate. b. Treat a little of the diazo-compound with dilute hydro- chloric acid. Treat a second portion with hot concentrated hydrochloric acid. Explain these changes. 115. Aminoazobenzene. Mix 1 g. of diazoaminobenzene with a little aniline hydrochloride (0.5 g.), and add to it about twice its volume of aniline. Heat this mixture at a temperature of about 40°-50° for 15-30 minutes. Pour this reaction product into an excess of very dilute acetic acid. Collect the separated solid and wash it with water. Boil the precipitate with 200 c.c. of water, and add concentrated hydrochloric acid cautiously until a sample of the deep-red liquid when cooled will deposit steel-blue needles. Filter the hot solution, and allow it to stand and cool until the crystals of the hydrochloride of aminoazoben- zene have separated. Aminoazobenzene itself may be made from the salt suspended in twice its volume of alcohol, by the action of concentrated ammonium hydroxide, added drop by drop, until the salt is dissolved and the color of the solution becomes brown. By careful treatment with water, aminoazobenzene will separate in yellow crystals. It may be recrystallized from dilute alcohol. § 118] AND DIAZO COMPOUNDS. AZO DYES 99 a. Immerse a piece of white woolen yarn in a hot solution of the hydrochloride of aminoazobenzene. After 10 minutes remove the yarn and wash it. Is it dyed? Can the color be removed by washing? _\116. Bismarck Brown. (First Azo-dye, 1866.) Make a dilute solution of meta-phenylenediamine, add to it a small crystal of sodium nitrite and a drop of dilute sulphuric acid. What is the nature of the reaction? How is this reaction em- ployed to detect and to estimate very small quantities of nitrites in drinking-water? “117. Helianthin. (Methyl Orange.) Dissolve 4.3 g. of sul- Piinilic acid in a dilute solution of sodium hydroxide con- taining 1 g. of the base. Add the calculated amount of sodium nitrite required to diazotize the sulphanilic acid; and, after cooling the mixture, pour into it the calculated amount of hydrochloric acid (1 mol). Dissolve the equivalent amount of dimethylaniline in a little hydrochloric acid and add it to the diazonium solution just prepared. When the mixture is made alkaline by the addition of sodium hydroxide, the azo-salt will separate at once. Collect the precipitate mon a filter and re- crystallize it from hot water. a. To a hot solution of the sodium salt, add dilute acetic acid. b. To a hot solution of the salt, add an excess of concentrated hydrochloric acid. How do you explain the different results obtained in a and 6? (Cf. Hantzsch, Ber. 41, 1187 (1908); Stieglitz, J. Am. Chem. Soc. 25, 112 (1903).) c. Reduction of Helianthine. Dissolve 3 g. of stannous chloride (SnCl.,2 H.O) in 6 c¢.c. of concentrated hydrochloric acid. Make a hot concentrated solution of helianthine (1 g.), and add the stannous chloride solution to it, until the color is entirely removed. When the mixture is cooled and stirred, sulphanilic acid will separate. What is the other reduction product? Benzidine Dyes. 118. Benzoblue. (Disazo-dye.) Dissolve 2.3 g. of benzidine in 7 g. of hydrochloric acid (sp. gr. 1.18) and 125 c.c. of water. Diazotize this solution, cooled by ice, by adding 1.7 g. of sodium nitrite dissolved in 10 c.c. of water. Pour the solution into an alkaline solution of 1,8-amino-naphthol 3,6-disulphonic acid 100 DIAZONIUM SALTS, ETC. [§ 119 (“H acid”). The dye will separate in brilliant needles. This dye will color wool without a mordant. a. What is Congo red? Trypan blue? 119. Polyazo-dye. Dissolve this benzoblue in slight excess of hydrochloric acid, and add to it the calculated amount of a sodium nitrite (.08 g. of nitrite for 1 g. of benzoblue). A deep greenish-blue diazonium compound will be formed. If this solution is poured into an alkaline solution of resorcinol, a dye will be formed which will color cotton green without a mordant. What is the meaning of the term substantive dye? adjective dye? CHAPTER XXII. PHENYLHYDRAZINE. NITROSAMINES. NITROSOPHENOL. DIPHENYLAMINE DYES. 120. Phenylhydrazine by the Reduction of a Diazonium Compound. Dissolve 10 g. of aniline in 100 c.c. of concen- trated hydrochloric acid. Cool the solution thoroughly by surrounding it with ice, and diazotize it by adding the calcu- lated amount of sodium nitrite. Pour the solution slowly into a cold solution containing 60 g. of stannous chloride (SnCl, 2 H:O) dissolved in concentrated hydrochloric acid. The hydrochloride of phenylhydrazine will be precipitated. After a short time, collect the crystals and drain them thor- oughly. This can be done best by means of a Biichner funnel and a pump. Treat the crystals with a slight excess of a solu- tion of sodium hydroxide, and extract the liberated hydrazine by means of ether. When the ether solution has been dried (12 hours) over solid potassium hydroxide, separate the solid and remove the ether by distillation. Distill the phenylhydra- zine in vacuo. Cf. Fig.17. An oil-bath or a metal-bath must be used to get a temperature high enough. At 12 mm., phenyl- hydrazine will boil when the temperature of the bath lies be- tween 120°-140°. a. What is the action of Fehling’s solution upon phenyl- hydrazine? 6. Compare the process of reduction of benzene diazonium - chloride in an alkaline solution of stannous chloride, with the process of reduction used above in the preparation of phenyl- hydrazine. 121. Para-nitrosodimethylaniline and its Hydrochloride. Mix 5 g. of dimethylaniline with 10.5 c.c. of concentrated hydro- chloric acid, and add to it some crushed ice (15 g.). Dissolve 3.2 g. of sodium nitrite in 10 c.c. of water, and add this solution gradually to the cold solution of the dimethylaniline salt. The hydrochloride of p-nitrosodimethylaniline will separate. Allow 101 102 PHENYLHYDRAZINE, ETC. [§ 124 the mixture to stand twenty minutes; then collect the salt upon a Biichner funnel, wash it with alcohol and ether, and recrys- tallize it, using 12 parts of dilute hydrochloric acid (1:1). It must not be heated above 60° during the process of solution. Its melting-point is 177°. To prepare the free nitroso-compound, suspend a part of the salt in water, and add a 10 per cent. solution of sodium carbonate until the yellow salt is decomposed. Extract the green nitroso- compound with a small amount of ether. Remove most of the ether by distillation, pour the remaining concentrated solution into an Erlenmeyer flask, and allow the solvent to evaporate until crystals of the nitroso-compound have separated. The melting-point is 77°. | a. Reduce a portion of the nitroso-compound, using a hydro- chloric acid solution of stannous chloride as the reducing agent. b. To another portion of the nitroso-compound, add a few drops of a solution of potassium permanganate. What is pre- cipitated? How could you identify it? c. Compare the behavior of dimethylaniline, a tertiary aro- matic amine, towards nitrous acid, with the behavior of aniline, a primary amine, and methyl aniline, a secondary aromatic amine, towards the same reagent. Have nitroso-derivatives resembling nitroso-dimethylaniline in form been obtained from primary and secondary amines? [RI]. Diphenylamine Dyes and Related Dyes. 122. Indoanilines. To a solution of phenol or of resorcinol in sodium hydroxide, add a small amount of nitroso-dimethylaniline. Shake the mixture with zinc dust until the color is removed. Filter the solution, and shake it with air. Explain the changes observed. Substitute a-naphthol for phenol, and repeat the experiment. 123. Indamines. ‘‘ Toluylene Blue.’? Mix a water solution of nitroso-dimethylaniline hydrochloride with a small amount of meta-toluylendiamine. To one portion, add sodium hydroxide; to a second portion, add an excess of hydrochloric acid. 124. Thiazine Dye. Methylene Blue. To a solution of p-nitrosodimethylaniline hydrochloride, add a few drops of ammonium sulphide and warm the solution gently. What is formed by the action of the sulphide? After a few seconds, add an excess of dilute hydrochloric acid and a few drops of ferric § 126] PHENYLHYDRAZINE, ETC. 103 chloride. Methylene blue will result. What is the formula of methylene blue? What relation does it bear to the indoanilines? 125. Safranine Dye. Mauve. (First Commercial Aniline Dye; Perkin, 1856.) Heat 1 g. of commercial aniline containing toluidine with a small excess of hydrochloric acid. To the clear solution, add a few cubic centimeters of a dilute solution of potassium dichromate. 126. Para-nitrosophenol, Quinone Monoxime. Heat a so- lution containing 25 g. of sodium hydroxide solution (sp. gr. 1.25) and 225 c.c. of water in a round-bottomed flask connected with a condenser and a receiver containing dilute hydrochloric acid. The end of the condenser-tube should just touch the surface of the acid in the receiver. To this solution, add small portions of p-nitrosodimethylaniline until 5 g. have been added. After the addition of each portion, close the flask, and allow the nitroso- compound to dissolve before a fresh sample is introduced. When all of the nitroso-compound has been used, boil the mix- ture until the dark-green color changes to a reddish-yellow tint. Cool the alkaline product, acidify it with sulphuric acid, and extract it with ether. When the ether has been distilled, nitroso- phenol will be left as a brown crystalline solid. Separate it, and dry it. It decomposes with a slight explosion at 120°-130°. If the hydrochloric acid in the receiver is evaporated on a water-bath, dimethylammonium chloride will be obtained. a. Liebermann’s ‘‘Nitroso’’ Reaction. Dissolve a few crys- tals of nitrosophenol (quinone monoxime) in an excess of phenol, and warm this mixture with concentrated sulphuric acid. A blue color will appear, which will change to red when the product is poured into water. CHAPTER XXIII. PHENOLS AND SOME RELATED COMPOUNDS. 127. Phenol by the Diazo-reaction. Pour 10 g. of aniline into 300 c.c. of water, and add gradually 8 c.c. of concentrated sulphuric acid. With this solution, cooled to 40°-50°, mix a solution of sodium nitrite containing the calculated amount necessary to diazotize the aniline salt. Heat this solution for 30 minutes on a water-bath at a temperature varying from 40°-50°. When a current of steam is passed into this liquid, phenol will distill, Add sodium chloride to the distillate, and extract the phenol by means of ether. Dry the ether extract, and subject the solution to fractional distillation. Phenol boils at 183°. a. Treat a small amount of phenol with a strong solution of sodium hydroxide. What do you observe? Acidify the alkaline solution. What is the result? b. Dissolve a drop of phenol in water, and add bromine water to it as long as the bromine is readily absorbed. Collect the precipitate upon a filter, dry it on a piece of porous plate, and determine its melting-point. This compound, 2,4,6-tribrom- phenol, is frequently used in detecting the presence of and in determining the quantity of phenol. c. Phenol from Benzene Sulphonic Acid. Fuse 1 g. of sodium hydroxide in a small porcelain crucible, and add 0.5 g. of sodium benzene sulphonate. Cf. §98. Continue the heating for five minutes, but avoid a temperature high enough to cause the fused mass to char. Cool the product and dissolve it in water. After making the solution acid by means of hydrochloric acid, filter it, and notice the odor of the filtrate. (?) Add bromine water in slight excess to the filtrate. Collect the precipitate, wash it, dry it, and determine its melting-point. (Cf. test b above.) d. To a dilute solution of phenol, add a few drops of a dilute solution of ferric chloride. 104 § 129] PHENOLS AND RELATED COMPOUNDS 105 e. Make dilute solutions of pyrocatechin and of resorcinol, and test each with ferric chloride. To the pyrocatechin solu- tion containing ferric chloride, add some sodium carbonate. This change in color is characteristic of pyrocatechin. f. Compare the behavior of the phenols with the reactions of acetoacetic ethyl ester and acetylacetone in the presence of ferric chloride. Cf. §63 and § 87. 128. Anisol, Phenyl Methyl Ether. Dissolve 15g. of phenol in 50 c.c. of water and 20 c.c. of 10 N. sodium hydroxide. Pour this mixture into a flask (250 ¢.c.) and add slowly 25 c.c. of dimethyl sulphate (commercial). Dimethyl sulphate is odor- less, but extremely poisonous. Be careful not to breathe the vapor. Perform the operation under a hood. The mixture will become so warm that thorough shaking and cooling of it will be necessary to keep the temperature between 40° and 50°, as shown by a thermometer placed in the mixture. At first, the clear liquid will become turbid; and, in the course of a few min- utes, a light layer of oil will float upon the surface. The re- action may be considered complete when the product no longer becomes warm spontaneously. (Cf. §75, Methyl Thiocyanate.) To destroy the excess of dimethyl sulphate, warm the mix- ture to the boiling-point, and shake it frequently. Finally, cool the liquid, make it slightly alkaline, and extract it with ether. Dry the ether solution with anhydrous potassium car- bonate. When the ether has been removed by distillation from a water-bath, distill the ether, and then the anisol. Anisol boils at 155°. The yield will be about 90 per cent. of the theo- retical amount. a. In what sense may anisol be considered as an ester? \ 129. Phenyl Benzoate. After mixing 0.5 g. of phenol with 5 c.c. water, add to it 0.8 g. of benzoyl chloride and enough sodium hydroxide solution to make the mixture slightly alkaline, even after it has been warmed and shaken. After the odor of benzoyl chloride has disappeared, cool the solution and allow it to stand for a short time. When the ester has solidified, collect it on a filter, wash it, and recrystallize it from alcohol. Dry the crystals, and determine the melting-point (69°). a. If this substance were boiled with a solution of sodium hydroxide, what would be formed? ‘Try the reaction. Acidify the alkaline solution. What is precipitated? 106 PHENOLS AND RELATED COMPOUNDS [§ 130 ' 430. Ortho- and Para-nitrophenol. Dilute 27 c.c. of con- centrated nitric acid with 70 c.c. of water and cool the mixture in a stream of water. To this dilute acid, add 20 g. of phenol in several small portions. While the phenol is being added, shake the flask constantly, and keep it cool. Allow the mixture to stand for 12 hours. When the layer which forms has been separated and washed with twice its volume of water, subject it to distillation in a current of steam. The Ortho Compound. Steam will carry over the ortho- nitrophenol in the form of a yellow oil, which will solidify par- tially in the condenser-tube. Collect these crystals and dry them on a porous plate; they are practically pure. They may be very successfully recrystallized as follows: — Dissolve them in 5 times their weight of dry ether and add 23 times their weight of petroleum ether. Pour this solution into an Erlenmeyer flask cover the flask loosely with a cap of filter-paper, and allow it to stand until the substance has crystallized. What is the principle involved in this method? The Para Compound. The para-nitrophenol, — which is not volatile with steam, — will remain in the flask as a brown tarry mass. In order to purify it, boil it for some time with a dilute (5 per cent.) solution of sodium hydroxide, and filter the dark- colored solution. Heat the filtrate with animal charcoal, and filter it again. When this alkaline solution has been concentrated to about one-third its original volume, treat it with a strong solution (50 per cent.) of sodium hydroxide. The sodium salt of para- nitrophenol will separate as the solution cools. Collect it upon a filter, dissolve it in the smallest amount of hot water possible, and precipitate it again by means of a concentrated solution of sodium hydroxide. (?) When the purified salt is suspended in water and treated with dilute sulphuric acid, para-nitrophenol will be formed. To purify it still further, recrystallize it from a small amount of hot water. a. Treat a few crystals of o-nitrophenol and of p-nitrophenol with a solution of sodium hydroxide. What is formed? Pass carbon dioxide through these solutions. Are the nitrophenols precipitated? Repeat the experiment, using phenol in place of the nitrophenols. Which is the more active acid, o-nitro- § 183] PHENOLS AND RELATED COMPOUNDS 107 phenol or phenol? Compare the hydrolysis of aniline salts and salts of substituted aniline derivatives with the behavior of these substituted phenols. Cf. Appendices D. and E. Do the nitrophenols decompose carbonates? 6b. How is the fact explained that para-nitrophenol and its esters are colorless while its salts are colored? (Hantzsch and Gorke, Ber. 39, 1073, 3074.) ve @ 131. Picric Acid. Dissolve 0.1 g. of phenol in 2c.c. of con- ‘centrated sulphuric acid. Pour this solution gradually into a mixture of 2 c.c. of concentrated sulphuric acid and 2 c.c. of concentrated nitric acid. After heating this mixture on a water- bath for 5-10 minutes, pour it into about 70 c.c. of cold water. When the product is cool, collect the precipitate upon a filter, and wash it with a mixture of 2 c.c. of water and 0.5 c.c. of concentrated hydrochloric acid. (?) Recrystallize the picric acid, using for this purpose a boiling mixture of 4 ¢c.c. of water and 1 ¢.c. of concentrated hydrochloric acid. When the precipi- tate has separated from the cool solution, collect it, and wash it with dilute hydrochloricacid as before. The melting-point is 122°. a. Is picric acid a more active acid than phenol? Does it decompose carbonates? b. How is picric acid employed as an explosive? as a dye? ~ 132. Para-amidophenetole from Phenacetin. Boil 5 g. of commercial phenacetin with 10 c.c. of concentrated hydrochloric acid and 10 c.c. of water. A few pieces of porous plate placed in the flask will prevent “‘bumping.’’ The hydrolysis will be complete in 20-30 minutes. When the solution has cooled, the odor of acetic acid will be noticeable, and the hydrochloride of para-amidophenetole will separate. Cf. §108, Acetanilid. The hydrochloride melts at 234°. Para-amidophenetole may be made from this salt as follows: — Dissolve one-half of the salt in water, and add a 10 per cent. solution of sodium hydroxide to it until the solution reacts distinctly alkaline. Separate the oil which forms, and extract the alkaline solution by means of ether. After drying the ether over potassium hydroxide, remove it, and distill the para-amido- phenetole. The boiling-point is 142°. a. Treat a water solution of it with ferric chloride. 133. Dulcin, p-Phenetole urea. Dissolve 2g. of the hydro- chloride of p-amidophenetole in 10 c.c. of water, and mix this 108 PHENOLS AND RELATED COMPOUNDS [§ 133 solution with a concentrated solution of 1.2 g. of potassium cyanate. The liquid will become filled with crystals of the urea. Collect the crystals upon a funnel, and recrystallize them from alcohol. Dulcin is about as sweet as cane-sugar. It is powsonous. a. In what respect does this reaction resemble the reaction involved in the preparation of urea from potassium cyanate and ammonium salts? CHAPTER XXIV. ALDEHYDES AND KETONES. _ Aldehydes. ~~ 184. Benzaldehyde. a. Shake several drops of benzaldehyde with a concentrated solution of sodium hydrogen sulphite. Collect the crystals upon a filter-paper, dry them, and heat them with a solution of sodium carbonate. Cf. §28, Acetone. b. Mix benzaldehyde with a solution of phenylhydrazine in 50 per cent. acetic acid. What is formed? Cf. § 28, Acetone. | c. Does benzaldehyde reduce an ammoniacal solution of silver nitrate? d. Rub a small amount of benzaldehyde on a watch-crystal, and allow it to stand exposed to air for some time. What change has taken place? e. Make a dilute solution of potassium iodide containing starch emulsion (cf. §92, Starch Iodide). Add a drop of benz- aldehyde to it. Shake the mixture frequently, and allow it to stand in the sunlight. What are oxidases? 135. Meta-nitrobenzaldehyde. Mix 100 c.c. of concentrated sulphuric acid and 8.5 c.c. of fuming nitric acid. Cool this acid to 0° in a freezing-mixture of ice and salt, and allow 25 g. of commercial benzaldehyde to flow into the acid very slowly, while the mixture is being stirred. During this stage, the tem- perature should not exceed +5°. Pour this product into a flask, and heat it slowly upon a water-bath until the temperature reaches 40°. Cool the product, and pour it slowly upon some crushed ice. Collect the m-nitrobenzaldehyde upon a Biichner funnel; dry it, and recrystallize it from a mixture of benzene and ligroine. Its melting-point is 58°. a. How do you explain the fact that benzaldehyde is oxidized on exposure to air, but is not readily oxidized by concentrated nitric acid at low temperature (+5°). Cf. §134, d and e. 109 - 110 ALDEHYDES AND KETONES [§ 137 136. Meta-chlorbenzaldehyde. Mix 20g. of meta-nitrobenz- aldehyde with a solution containing 90 g. of crystallized stannous chloride and 125 g. of fuming hydrochloric acid. The temperature may increase to such an extent that external cool- ing will be necessary. When the aldehyde has passed into solution, dilute the acid with water, and add sufficient ice to lower the temperature to 0°. ‘ While you shake this mixture, pour into it, very slowly, a solution of 9.2 g. of sodium nitrite dissolved in 35 c.c. of water. Prepare a solution of cuprous chloride by boiling 6 g. of crystal- lized cupric chloride and 3 g. of copper turnings with 25 c.c. of hydrochloric acid and 6 ¢.c. of water. When this solution has been cooled to about 0°, pour the diazonium solution into it. (Cf. Sandmeyer’s reaction.) After 24 hours, distill the m-chlorbenzaldehyde with steam; separate the oil, and dry it with calcium chloride. Subject it to fractional distillation, and collect the fraction which boils between 210° and 216°. When this fraction is cooled in a freez- ing-mixture, it will yield solid m-chlorbenzaldehyde. The solid may be freed from oil by means of a Biichner funnel and a pump. It boils at 213°-214°; its melting-point is 17°-18°. 137. Stereoisomeric Aldoximes. Meta-chlor-a-benzaldoxime. Dissolve 10 g. of m-chlorbenz- aldehyde and 6 g. of hydroxylamine hydrochloride in 200 c.c. of water. Heat this mixture in a flask placed upon a water-bath. Pass a stream of carbon dioxide into the flask. (?) After sev- eral hours, cool the solution, and collect the crystalline oxime upon a filter. Recrystallize it from 95 per cent. alcohol. It melts at 70°-71°. It is also called meta-chlor-anti-benzald- oxime. Conversion into Meta-chlor-B-benzaldoxime. Dissolve 5 g. of the oxime in 50 c.c. of dry ether, and conduct into it a stream of dry hydrogen chloride gas. (Cf. Appendix G.) The hydrochloride of the oxime will finally separate as a white cry- stalline solid. Collect this salt upon a filter protected as much as possible from moist air. Wash the salt with absolute ether, and dry it in a vacuum-desiccator over sulphuric acid. To prepare the B-oxime itself, mix 5 g. of this hydrochloride with a solution of 2.5 g. of sodium carbonate in 25 ¢.c. of water. A colorless oil will form at first; after it is shaken, it will solidify. § 139] ALDEHYDES AND KETONES 111 Recrystallize the B-oxime from dilute alcohol. It is also called the syn-oxime. This solid will melt at 115°-116°; but, at the same time, it will be converted into the a-oxime. The fused substance, when it has solidified once more, will be found to melt at 70°-71°, instead of 115°-116°. , a. What is the significance of the terms syn and anti (a and 8) as applied to aldoximes? How are space configurations chosen for two geometrical isomeres? Ketones. 138. Benzophenone. Friedel and Crafts’ Reaction. In a 1-liter flask, mix 15 g. of anhydrous aluminium chloride with 50 c.c. of dry carbon disulphide. Through the stopper of this flask, pass a dropping-funnel and a bent adapter connected with a long condenser. At the upper end of this condenser, insert a calcium chloride tube bent downward and containing calcium chloride. From this tube there should be a long glass tube which reaches into a bottle and ends just above the surface of some water placed in the bottle. Into the dropping-funnel, pour a mixture of 15 g. of benzoyl chloride and 15 g. of dry benzene, and allow it to flow into the flask gradually. Heat the flask in a water-bath for two or three hours, or until the evolution of hydrogen chloride has practically ceased. Remove the carbon disulphide by distillation in the usual -way, and pour the residue into ice water. After adding 10 c.c. of concentrated hydrochloric acid, conduct steam into the product, and collect the distillate. Extract the ketone by means of ether, wash the ether with a solution of sodium hydroxide, and dry it. When the solvent has been removed subject the ketone to distillation. Use a small flask with a long side neck joined near the bulb, and without condenser attached to it. Benzophenone boils at 360°. Its melting-point is 48°. . 139. Benzophenoneoxime. Dissolve 5 g. of benzophenone and 6 g. of hydroxylamine hydrochloride in 65 c.c. of alcohol and 40 c.c. of water. Add 10 g. of sodium hydroxide dissolved in 15 c.c. of water, and boil the mixture for about an hour in a flask attached to a reflux-condenser. Dilute the product with a large volume of water, and acidify it with dilute sulphuric acid. After several hours, collect the crystalline oxime, wash it with water, and dry it. The melting-point is 141°. The yield will be nearly quantitative. (Cf. §31, Acetoxime.) 112 ALDEHYDES AND KETONES [§ 141 Beckmann’s Rearrangement of a Ketoxime. Dissolve 3 g. of benzophenoneoxime in 40 c.c. of ether dried over sodium. In a closed weighing-bottle, weigh out 4 g. of phosphorus penta- chloride in the form of a fine powder, and add it in small por- tions to the ether solution. Remove the ether by distillation, and pour the residue upon ice ina mortar. Grind the solid very fine, collect it upon a Bichner funnel, and wash it with water. When the benzanilid is dry, recrystallize it from boiling alcohol. The melting-point should be 162°. a. How is this reaction employed to determine the space configurations of stereoisomeric ketoximes? 140. Benzophenone Phenylhydrazone. Dissolve 1.5 c.c. of phenylhydrazine in 5 ¢.c. of acetic acid (30 per cent.), and add to this solution 1 g. of benzophenone. The hydrozone will form readily when the mixture is thoroughly shaken. Collect it upon a filter and wash it. Dissolve it in a little hot alcohol and filter the solution if necessary. Add water to the filtrate until it shows a slight turbidity; then allow the solution to cool. The hydrazone will separate in crystalline form. It melts at 105°. 141. Quinones and Related Compounds. a. Benzoquinone, Quinone. Dissolve 10 g. of aniline in a mixture of 54 g. of concentrated sulphuric acid and 200 c.c. of water. Cool this solution to about 10°, and add 6.4 g. of finely powdered potassium dichromate. This salt should be introduced slowly in one-gram portions. The operation should require about 20 minutes, during which the flask must be shaken very frequently. When all of the dichromate has been added, allow the flask to stand over night; then, with the conditions the same as before, add 13.5 g. of powdered potassium dichromate. The bluish color will finally change to brown. Extract the solution repeatedly with ether. If an emulsion should form which prevents the separation of the layers, a few cubic centimeters of alcohol will cause the liquids to part. When the ether has been removed by distillation, impure quinone will be left. The further purification of quinone may be accomplished by subjecting it to distillation in a current of steam. Place the solid in a distilling-flask, and conduct into it a rapid current of steam. Bright yellow crystals of quinone will collect in the con- denser and in the receiver. It may be recrystallized from ligroin. § 141] ALDEHYDES AND KETONES 113 a. Notice the odor of quinone. 6. Add a few crystals of quinone to an acidulated solution of potassium iodide. What class of chemical compounds does quinone resemble in this reaction? y. Dissolve some quinone in chloroform, and add to it a solution of bromine in chloroform. What does this reaction suggest concerning the constitutional formula of quinone? 6. Reduction of Quinone to Hydroquinone. Dissolve 5 g. of quinone in 100 c.c. of commercial soditim bisulphite solution (40 per cent.). It may be necessary to warm the mixture slightly.* After cooling the reaction product, extract the solu- tion repeatedly with ether. When the ether has been dried with anhydrous sodium sulphate, and removed by distillation, hydroquinone will be left as a slightly colored residue. It may be recrystallized from a little water containing sulphurous acid and animal charcoal to remove the color. The melting- point is 169°. a. To an alkaline solution of hydroquinone, add an ammoni- acal solution of silver nitrate. gB. Treat a concentrated solution of hydroquinone with ferric chloride. Try the same reaction with a dilute solution of hydroquinone and an excess of ferric chloride. Heat the mix- ture and observe the odor. y. Acetyl Derivative, Hydroquinonediacetate. Suspend some hydroquinone in twice its weight of acetic anhydride to which one drop of concentrated sulphuric acid has been added. Cool the product, collect the solid, and wash it with water. 6. What structure formule have been proposed for quinone? Discuss the bearing of reactions a, 8, and y in both a and 8, as evidence in support of, or in disproof of one or the other of these formule. c. Dinitroso Resorcinol, Dichinoyldioxime.{ Dissolve 5 g. of resorcinol in 20 c.c. of water containing 10 c.c. of concentrated hydrochloric acid, and 25 g. of sodium chloride. Cool the solu- tion thoroughly by ice, and add slowly a cold solution of sodium nitrite containing 6.4 g. of sodium nitrite in 25 c.c of water. * Note 11. — As an alternative, suspend the quinone in a little water, and pass a rapid stream of sulphur dioxide into it until the solution be- comes almost colorless. } Hantzsch, Ber. 39, 162. 114 ALDEHYDES AND KETONES [§ 141 After one hour, collect the precipitate, wash it with a little cold water, and dry it. Cf. § 126, Nitrosophenol. This compound is known as resorcin green or fast green, and is employed with iron salts as mordants to color cotton green; wool may be dyed green by it without a mordant. | CHAPTER XXV. AROMATIC ACIDS AND THEIR DERIVATIVES. J 142. Benzoic Acid by the Oxidation of Benzaldehyde. - Heat a few drops of benzaldehyde with an aqueous solution of potassium permanganate. What is the precipitate formed? When the odor of benzaldehyde has disappeared, add a few drops of alcohol to decompose any excess of permanganate. Filter the liquid An acidify the filtrate. Benzoic acid will be precipitated. a. Are the processes usually employed in making benzoyl chloride, benzamide, benzoic ethyl ester similar in form to those which were used to make the corresponding derivatives of acetic acid? 143. Benzoic Anhydride. Dissolve equa-molecular quanti- ties of benzoic acid and acetic anhydride in dry benzene, and boil the mixture for 6 hours. Subject the product to frac- tional distillation. The last fraction, which boils between 347° and 348°, is practically pure benzoic anhydride. The yield should be 80 per cent. (Kaufman and Luerbacher, Ber. 42, 3483.) a. How is nitrogen pentoxide usually prepared? Is there any analogy between this method and the method just described? 144. Benzoyl Peroxide.” Gradually dissolve some commercial sodium peroxide in a solution of sodium acetate, thoroughly cooled by crushed ice. Shake this solution with several drops of benzoyl chloride until a crystalline precipitate forms. Re- crystallize the solid, using alcohol as the solvent. Benzoyl per- oxide will be obtained. It will melt at 103°. a. Heat a small sample of the solid. b. Warm a little of it with an acidulated solution of potas- sium iodide. Explain your observation. Cf. § 134, Benzalde- hyde, e. * Pechman and Vanino, Ber. 27, 1511. 115 116 AROMATIC ACIDS [§ 147 145. Salicylic Acid from Oil of Wintergreen. Mix 1 g. of oil of wintergreen (methyl salicylate) with a solution of 2.5 g. of sodium hydroxide in 15 ¢.c. of water. Heat this mixture in a flask connected with a reflux-condenser. When all the oil has disappeared, acidify the solution, and separate the solid by filtration; dry the acid, and determine its melting-point. a. How is salicylic acid obtained in large quantities? b. How could you prepare oil of wintergreen synthetically? Heat some salicylic acid with soda lime. Observe the odor. What is formed? c. To a dilute solution of salicylic acid, add a few drops of a very dilute solution of ferric chloride. What use is made of this reaction in detecting small amounts of salicylic acid; e.g.,in foods? 146. Mandelic Acid Nitrile. Shake 15 g. of benzaldehyde with 50 c.c. of concentrated sodium hydrogen sulphite solution. Collect the addition product which forms, and wash it with a little water. Stir this substance with water enough to make a thick mixture, and pour into it a solution of 12-g. of potasstum cyanide dissolved in 15 c.c. of water. When this mixture is stirred, the solid will go into solution, and an oil will form. This oil is the nitrile; it is very unstable. a. Mandelic Acid from its Nitrile. Treat the nitrile with four times its weight of concentrated hydrochloric acid, and evaporate the mixture upon a water-bath until a crystalline film begins to form upon the surface of the liquid. When this solution has stood for several hours, collect the crystalline product, and extract the filtrate with ether to remove the re- mainder of the acid. Recrystallize the acid from water, or from benzene. Mandelic acid melts at 118°. 147. Gallic Acid. a. Add a few drops of ferric chloride to a water solution of gallic acid. b: Rufigallic Acid. Moisten a small amount of gallic acid with concentrated sulphuric acid. Warm the acid until the mixture turns deep red; then pour the product into a little cold water. Rufigallic acid is a derivative of anthraquinone. Cf. Alizarin. c. Heat a little gallic acid in a dry test-tube. Does the liberated gas affect lime water? What are the chief products of decomposition? § 148] AND THEIR DERIVATIVES 117 148. Tannin. a. Treat a water solution of tannin with a few drops of ferric chloride. How are “iron” inks made? b. Soak a small piece of gelatine in cold water until it swells. Warm this gelatine with the water until it dissolves. Cool the solution and add tannin to it. What occurs? How is tannin employed in the tanning processes? CHAPTER XXVI. DERIVATIVES OF DIPHENYLMETHANE AND OF DIPHENYLETHANE. 149. Tetramethyl-p-diamidodiphenylmethane. Mix 1 c.c. of formalin solution with 10 c.c. of water, and add 0.5 c.c. of dimethylaniline. Acidify the mixture with dilute sulphuric acid and shake it vigorously for a few minutes. When this product has been made slightly alkaline by means of sodium hydroxide, boil it in a dish until the odor of dimethylaniline is no longer noticeable. | Tetramethyl-p-diamidodiphenylmethane will be precipitated. Collect this precipitate upon a small filter, and wash it with water. Spread the filter in a small porcelain dish; moisten it with dilute acetic acid, and sprinkle upon it some finely powdered lead dioxide. A blue dye (hydrole) will result. (?) a. How is this reaction employed in similar cases as an in- termediate stage in making various triphenylmethane dyes com- mercially? 150. Benzoin. ‘‘ Benzoin Condensation.’’ Dissolve 10 g. of benzaldehyde in 12 c.c. of alcohol, and add to it a solution of 1g. of potassium cyanide in 10c.c. of water. Connect the flask with a reflux-condenser, and heat this solution for 15 minutes. When the liquid has cooled, benzoin will separate; it should be collected upon a filter, and crystallized from alcohol. It may be necessary to use a little animal charcoal to remove coloring matter. The melting-point is 134°. a. Does benzoin reduce Fehling’s solution? Cf. §89, Mono- saccharides. 151. Benzil. Mix 5g. of benzoin with 15 c.c. of concentrated nitric acid (sp. gr. 1.4). Shake the mixture frequently, and heat it upon a water-bath until oxides of nitrogen are no longer visible and a sample poured into water gives a precipitate which, when dissolved in alcohol, will not reduce Fehling’s solution. If this test shows no reduction, pour the acid solution in ~ water, and collect the crystals upon a Biichner funnel. Re- crystallize the benzil from alcohol. The melting-point is 95°. a.. What is benzilic acid? How is it obtained from benzil? 118 CHAPTER XXVII. DERIVATIVES OF TRIPHENYLMETHANE — TRIPHENYLMETHANE DYES. Triphenylmethane Dyes. 2 -\ 152. Malachite Green. (Leuco-base.) Mix 10 g. of di- methylaniline, 4 g. of benzaldehyde, and 8 g. of anhydrous zinc chloride, and heat the mixture in a porcelain dish over a water- bath. This mixture should be stirred frequently, and a little water should be added to prevent it from becoming too thick by evaporation. After several hours, transfer the product to a flask, and remove the unchanged dimethylaniline by steam dis- tillation. Cool this residue and pour away the solution of zinc chloride. Wash the impure leuco-base and dissolve it in hot absolute alcohol. Upon cooling, the leuco-base will separate in crystals, almost colorless. By repeated crystallization, it may be obtained colorless. —~\ 153. Malachite Green. (Dye.) Dissolve 3 g. of the leuco- base in 36.3 c.c. of normal hydrochloric acid, and dilute the solution with 275 c.c. of water. Cool this solution, and add 2.2 g. of lead dioxide which has been suspended in 20 c.c. of water. This operation should require about 5 minutes. The mixture should be shaken for 5 minutes after all of the lead dioxide has been introduced. Filter the solution, add 3.5 g. of zine chloride, and then a sufficient amount of a saturated solution of salt to precipitate the dye so completely that a filtered sample of the mother liquor shows only a faint green color. Collect the dye and wash it with salt solution. It may be purified by dissolving it first in hot water, and then reprecipitating it by means of saturated salt solution. Finally, collect the dye, and dry it upon a piece of porous plate. a. Treat a sample of malachite green with an excess of con- centrated hydrochloric acid. (?) Add a large volume of water. 6. Add asolution of sodium hydroxide to a sample of malachite green. (?) 119 120 TRIPHENYLMETHANE DYES [§ 157 c. Treat a sample of the dye with zinc dust and hydrochloric acid. Explain these changes. 154. Parafuchsine, Pararosaniline Hydrochloride. (Dye.) Mix 1 ¢.c. of aniline with 1 g. of p-toluidine and 3 g. of mercuric chloride. Heat this mixture to a temperature of 180°-200° for 15 minutes. Extract the residue with alcohol, filter the solution, and evaporate it. Make a water solution of the residue, and acidulate it with dilute hydrochloric acid. a. Add concentrated hydrochloric acid to one portion of the solution. Explain the change in color. [RI]. b. Pararosaniline. (Color-base.) To a second portion of the solution, add ammonium hydroxide or sodium hydroxide. The color will be removed. Explain this reaction. c. Paraleucaniline. (Leuco-base.) To a third portion of the solution, add zinc dust, and warm the mixture. How is the color removed? 155. Rosolic Acid. Heat a mixture of 2 c.c. of phenol, 0.5 g. of oxalic acid, and 5 c.c. of concentrated sulphuric acid. Pour the red liquid into water, and add a slight excess of sodium hydroxide. The sodium salt of rosolic acid will be formed. Phthaleins. 466. Phenolphthalein. Mix a small crystal of phenol with an equal volume of powdered phthalic anhydride. Place the mixture in a small test-tube, moisten the powder with one drop of concentrated sulphuric acid, and heat the tube for three minutes in a bath whose temperature is about 160°. Cool the residue, dissolve it in about 2 ¢.c. of water, and add 1 c.c. of a 10 per cent. solution of sodium hydroxide. Filter the solution and pour the filtrate into water. —\ 157. Fluorescein. If resorcinol is substituted for phenol in preparation 156, and the other conditions are kept the same, fluorescein will be obtained. Notice the intense fluorescence of the water solution. :.08) 20 —2.0 PoOtAassiuTO NIUTaALe ot ea hee ee 13 —2.85 Potassium chlorides... 3.440. ee 30 —10.9 Ammonium chioridé?..22..0 4502. seen 25 —15.4 Ammonium nitrate, 265.63. eee 45 —16.75 Sodium nitrate ii ks ae: eee 50 —21.3 Sodium: chloride :so40224) bee eee 30 —22.4 Calcium chloride crys. (CaClz+2 HO). 143 —50 Solid carbon dioxide and ether ........ —100 TABLE IV. — Comparison of the Various Heat Units. At the present time, several different heat units are employed to designate quantity of heat. The following ones are most frequently used: — a. The Gram Calorie (Small Calorie), cal., is equal to the amount of heat absorbed by one gram of water in warming one degree C. This quantity, however, is not the same for all 1° intervals; e.g., the amount of heat necessary to warm a gram of water from 0° to 1° is a somewhat different value from that which is required to heat it from 99° to 100°. Practically, the calorie measured between 15° and 16° is the most convenient. 1 gram calorie =42,720 gram centimeters (mechanical equiva- lent of heat). 6. The Kilogram Calorie (Large Calorie), Cal., is the amount of heat required to raise the temperature of one kilo- gram of water 1°C. Here, again, it will be evident that this quantity will vary with the different unit intervals chosen. c. The British Thermal Unit, B.T.U., is quite generally employed in engineering work in America and in England. It may be defined as the amount of heat necessary to raise the APPENDICES 141 temperature of one pound of water 1° F. Since 1 pound is equal to 453.6 g., and 1° F. is equivalent to 3° C., it follows that 1 B.T.U. = 453.6 X 8 = 252 gram calories. Consequently 1 Cal. = 1000 cal. = 3.97 B.T.U._ 1 B.T.U. = 252 cal. = 0.252 Cal. 1 cal. = 0.001 Cal. = 0.00397 B.T.U. Heat Value, Calorific Power, Heat of Combustion are ex- pressed in calories per gram or in B.T.U’s per pound of substance. It is evident that the unit of mass in comparing these two numerical values will cancel; and in consequence, one calorie per gram (cal.) may be read as 3 B.T.U’s per pound. Thus, although the absolute value of 1000 cal. in quantity of heat is 3.97 B.T.U’s, a heat value of 1000 cal. per gram may be read as 1800 B.T.U’s per pound. APPENDIX B. PRESSURE MEASUREMENT. TABLE V.— Correction of Barometric Readings. To reduce the reading taken at room temperature (Tem- perature) to the corresponding height of a column of mercury at 0°, subtract the proper number in the second column (Correction) from the actual reading in millimeters. Tempera- : Tempera- : Tempera- ture. Correction. ture. Correction. Correction. Tempera- Tempera- Tempera- Pressure. ture. Pressure. ture. Pressure. 13.5 25.1 14.4 26.5 15.4 28.1 16.3 29.8 17.4 31.8 18.5 33.4 19.7 35.4 20.9 37.4 22.2 39.6 23.6 760.0 et et pe WHE HODOOOMD”E WON MON AOUNAD 142 APPENDIX C. VOLUME AND WEIGHT RELATIONS. SPECIFIC GRAVITY. By specific gravity * of a liquid is meant its relative weight compared with the weight of an equal volume of pure water at some definite temperature. Since the density of a liquid varies as its temperature changes, the scale is adjusted to a certain temperature, usually 15°C. with water at 15° = 1. In some of the following tables the values are based upon water at 15°. In order to transpose these values to the basis of water at its greatest density (+ 4°), it will be necessary to multiply the values in such tables by 0.99916. Two other scales are still in use in technical work; viz., the Baumé and the Twaddell. Baume. On the Baumé hydrometer, the scale readings bear no direct relation to actual specific gravity. Baumé dissolved 15 parts of pure sodium chloride in 85 parts of water at 12.5° C. The point to which his instrument sank in this solution was marked 15, while the point to which it sank when placed in pure water was marked 0. The distance between these two points was divided into 15 equal parts, and the stem was calibrated in divisions of this width. The divisions are called degrees. In the case of liquids lighter than water, the point to which the instrument sank in a 10 per cent. solution of sodium chloride solution was marked 0; while the point to which it sank in pure water was marked 10. The distance between these two points was divided into 10 equal parts, and the stem was graded in equal divisions through its entire length. This instrument is extremely unscientific in principle. Thus, since the 0 is placed at the bottom of the stem, the lighter the gravity of the liquid the greater numerically is the scale reading; e.g., a liquid read- ing 70 Bé. is of a less density than one of 50 Bé., which, in turn, is lighter than water at 10 Bé. * This account, slightly modified, is taken from Thorp’s “‘ Outlines of Industrial Chemistry.” 143 144 APPENDICES Twaddell’s Hydrometer. The spindle of Twaddell’s hydrom- eter is graduated from 1 to 174. The readings are direct. The reading of pure water at 15.5° C. is taken as 0, and each subse- quent rise of 0.005 in specific gravity is recorded on the scale as one additional division. Thus, 10 Twaddell becomes a specific gravity of 1.050. The divisions are spoken of as degrees. Interconversion of Various Scale Values. Tw. = reading Twaddell; Bé. = reading Baumé; Sp. gr. = Specific gravity. 144.3 ote ; 5 Sp. er, = eee ne. for liquids heavier than water. 15° C. 14 Pore Tees . Sp. gr. = 130 + Bé. for liquids lighter than water. 17.5° C. Sp. gr. = 1+ (Tw. x 0.005) 15.5° C, TABLE VII. — Table of Specific Gravity and Percentage of Sodium Hydroxide in Aqueous Solutions. SPECIFIC GRAVITY AT 15° COMPARED WITH WATER AT 15°=1. (Lunge.) Le 1. io i tS 1; Le i: iy is 13 1. i, ie Ly is i; Li dis a. i; a2 1; {; 1; APPENDICES 145 TABLE VIII.— Table of Specific Gravity and Percentage Composition of Ammonia in Aqueous Solution. The correction values in the fourth column hold for the tem- perature interval 13-17°. For example, if the specific gravity at 13° were found to be 0.900, the specific gravity at 15° would be less, and would be found by subtracting 2 x 0.00057 = 0.001 from the value observed. This would give for the specific gravity 0.899, or an ammonia content about one-third of one per cent. higher. | SPECIFIC GRAVITY AT 15° COMPARED WITH WATER AT 15°= 1. (Lunge and Wiernik.) 1 |. con- ns . Sp. Gr.| Nie Sp. Gr| Rie | NE at | Comsetion a LS EE SS ce (en (| 1.000 | 0.00] 0.0 | 0.00018 } 0.940! 15.63] 146.9 | 0.00039 0.998 | 0.45] 4.5 | 0.00018 | 0.938] 16.22) 152.1 | 0.00040 0.996 | 0.91) 9.1 | 0.00019 | 0.936] 16.82] 157.4 | 0.00041 0.994 | 1.37] 13.6 | 0.00019 § 0.934] 17.42] 162.7 | 0.00041 0.992 | 1.84] 18.2 | 0.00020 | 0.932) 18.03] 168.1 | 0.00042 0.990 | 2.31| 22.9 | 0.00020 | 0.930) 18.64] 173.4 | 0.00042 0.988 | 2.80] 27.7 | 0.00021 } 0.928) 19.25] 178.6 | 0.00043 0.986 | 3.30] 32.5 | 0.00021 | 0.926] 19.87/ 184.2 | 0.00044 0.984 | 3.80] 37.4 | 0.00022 | 0.924] 20.49] 189.3 | 0.00045 0.982 | 4.30] 42.2 | 0.00022 | 0.922) 21.12] 194.7 | 0.00046 0.980 | 4.80] 47.0 | 0.00023 | 0.920) 21.75] 200.1 | 0.00047 0.978 | 5.30] 51.8 | 0.00023 | 0.918] 22.39] 205.6 | 0.00048 0.976 | 5.80] 56.6 | 0.00024 | 0.916] 23.03] 210.9 | 0.00049 0.974 | 6.30| 61.4 | 0.00024 | 0.914] 23.68] 216.3 | 0.00050 0.972 | 6.80] 66.1 | 0.00025 | 0.912) 24.33] 221.9 | 0.00051 0.970 | 7.31] 70.9 | 0.00025 | 0.910) 24.99] 227.4 | 0.00052 0.968 | 7.82] 75.7 | 0.00026 | 0.908] 25.65] 232.9 | 0.00053 0.966 | 8.33/ 80.5 | 0.00026 | 0.906] 26.31] 238.3 | 0.00054 0.964 | 8.84 85.2 | 0.00027 | 0.904) 26.98] 243.9 | 0.00055 0.962 | 9.35] 89.9 | 0.00028 | 0.902] 27.65] 249.4 | 0.00056 0.960 | 9.91] 95.1 | 0.00029 | 0.900] 28.33] 255.0 | 0.00057 0.958 | 10.47| 100.3 | 0.00030 | 0.898] 29.01] 260.5 | 0.00058 0.956 | 11.03] 105.4 | 0.00031 | 0.896] 29.69] 266.0 | 0.00059 0.954 | 11.60] 110.7 | 0.00032 | 0.894] 30.37] 271.5 | 0.00060 0.952 | 12.17] 115.9 | 0.00033 | 0.892) 31.05] 277.0 | 0.00060 0.950 | 13.74] 121.0 | 0.00034 | 0.890) 31.75] 282.6 | 0.00061 0.948 | 13.31] 126.2 | 0.00035 | 0.888] 32.50] 288.6 | 0.00062 0.946 | 13.88] 131.3 | 0.00036 } 0.886) 33.25] 294.6 | 0.00063 0.944 | 14.46] 136.5 | 0.00037 | 0.884| 34.10) 301.4 | 0.00064 0.942 | 15.04] 141.7 | 0.00038 | 0.882) 34.95] 308.3 | 0.00065 146 APPENDICES TABLE IX. — Table of Specific Gravity and Percentage Com- position of Hydrochloric Acid at 15°C. Water at 4° =1. (Lunge and Marchlewskt.) seh Per cent. sere Per cent. 15° Per cent. HCl HCl Cl es by weight. 73 by weight. by weight. in vacuo. fe ee ja a ee ee el See ee ee ee ee en ee ell aes TABLE X. — Table of Specific Gravity and Percentage Com- position of Solutions of Sulphuric Acid at 15°C. Water bs at 4°= 1. (Lunge and Isler.) Sp. gr. 100 parts by Sp. gr. 100 parts by 15° weight con- 15° weight con- 4° tains per cent. 4° tains per cent. in vacuo. H2SOs. in vacuo. H2SOs. .650 72.82 700 vp he be 3 .750 81.56 .800 86.90 .810 88.30 .820 90.05 .830 92.10 .834 93.05 .840 95 .60 .8415 97.70 .840 99 .20 .8385 99.95 . 8384 100.00 .000 0.09 .050 7.37 . 100 14.35 . 150 20.91 . 200 27 .32 .250 33.48 . 300 39.19 .350 44.82 .400 50.11 .450 55.03 . 900 59.70 .550 64.26 . 600 68.51 1 1 1 i 1 1 1 1 1 1 1 1 1 ee 147 TABLE XI.—Table of Specific Gravity and Percentage ee of Solutions of Nitric Acid at 15°. Water at 4°=1. APPENDICES (Lunge and Rey.) 100 parts by 100 parts by jo" weight con- jo” weight con- 4° tain ae cent. 4° tain per cent. in vacuo. HNO. in vacuo. HNO. Sp. gr. 15° Sp. gr. Loe .400 63 .30 415 68 .63 .450 77 28 .900 94.09 .905 96.39 .510 98.10 515 oUF .920 99.67 .000 .050 .100 .150 . 200 .250 . 300 .390 fe el ek el et et ee ee a ee TABLE XII.—Table of Specific Gravity and Percentage Composition of Solutions of Alcohol and Water at Vari- ous Temperatures. Water at 4° = 1. (Mendelejeff.) Per cent. by weight of alcohol. Specific gravity of alcohol-water mixtures. 0.99988 0.99135 0.98493 0.97995 0.97566 0.97115 0.96540 0.95784. 0.94939 0.93977 0.92940 0.91848 0.90742 0.89595 0.88420 0.87245 0.86035 0.84789 0.83482 0.82119 0.80625 0.99831 0.98945 0.98195 0.97527 0.96877 0.96185 0.95403 0.94514 0.93511 0.92493 0.91400 0.90275 0.89129 0.87961 0.86781 0.85580 0.84366 0.83115 0.81801 0.80433 0.78945 0.99579 0.98680 0.97892 0.97142 0.96413 0.95628 0.94751 0.93813 0.92787 0.91710 0.90577 0.89456 0.88304 0.87125 0.85925 0.84719 0.83483 0.82232 0.80918 0.79553 0.78096 148 APPENDICES TABLE XIII. — Table of the Solubility of Sodium Chloride in Water. 100 PARTS OF WATER BY WEIGHT DISSOLVE THE GIVEN WEIGHTS. (De Coppet.) APPENDIX D. DISSOCIATION CONSTANTS OF ORGANIC ACIDS AND BASES. Ostwald’s Dilution Formula. When an electrically neutral molecule, A, dissociates, A= mA,+ NeAe+ See (1) it follows in accordance with the law of mass action that eee Ct SOs, (2) The same formula applies to the dissociation of electrolytes, if c be chosen to represent the concentration of the undissociated part in terms of gram molecules per liter, and c; and c; the con- centrations of the ions (dissociation products) in terms of gram ions per liter. Since the ions occur in electrically equivalent amounts, the following formula holds for a binary electrolyte: Ke= c,2. (3) And if a represents the degree of dissociation (part dissociated) determined by any of the various physical methods — e.g. osmotic pressure methods or the electrical conductivity method, —and if V represents the volume which contains one gram molecular weight, then it follows that C= ee) and V ci = ae (4) consequently, from equations (3) and (4), KV (1 — a) =@?, (5) a? or K = ean (6) In other words, the undissociated part per unit volume is pro- portional to the product of the concentrations of the constituent 149 150 APPENDICES ions, and the proportionality factor is called the Dissociation Constant or Ionization Constant. This formula, known as Ostwald’s dilution formula, applies rigorously only to the less active acids and bases. Furthermore, solving this equation for a, yah) Most of the constants given in the following tables are numeri- cally equal to 100 times the constants obtained by Ostwald’s dilution formula. Such values are designated by the symbol 100 K. Ina few cases, other multiples are used. In the system of notation employed to designate these values, 10 stands for unity followed by ten ciphers; 10—!° means a decimal point fol- lowed by nine ciphers and unity. 109 = au 10,000,000,000 107° = Se 0.0000000001. 1010 TABLE XIV. — A Comparison of the Dissociation Constants of Certain Weak Acids, Organic and Inorganic. Temper- ature = 25°. Substance. Formula. K X 102, H.NO, 6,400,000 H.C.H;02 180,000 Carbonic Hydrogen sulphide Water (C+ Con: = Ky,0) APPENDICES Pisa TABLE XV.— Monobasic Fatty Acids and Some of their Substitution Products. Temperature = 25°. Substance. Formula. 100 K. Formic (Ostwald). H.COOH 0.02140 Acetic (Ostwald). . CH;.COOH 0.00180 PLOULONIC.’. ....... CH;.CH2.COOH 0.00145 Butyric CH:3.(CH2)2,. COOH 0.00175 Valerianic CH;.(CH2)3. COOH 0.00156 i CH3.(CH2)4. COOH 0.00147 CH;.(CH2)s. COOH 0.00146 HaAtoGgen Derivatives or Acetic Acip. (OsTWALD.) Monochloracetic.. . CH.Cl.COOH 0.155 Dichloracetic CHCl..COOH 5.144 Trichloracetic..... CCl;. COOH 120.00 A Series OF SuBsTITUTION Propucts or Acetic Acip ILLUS- TRATING THE EFFECT OF VARIOUS UNIVALENT SUBSTITUENTS UPON THE DISSOCIATION CONSTANT. (OSTWALD.) CH;.COOH 0.0018 Phenylacetic CH:2(C.H;). COOH 0.00556 Glycollic CH.(OH).COOH 0.0152 Thioglycollic CH.(SH).COOH 0.0225 Monobromacetic. . CH.Br.COOH 0.138 Monochloracetic .. CH.2Cl.COOH 0.155 i CH.(COOH).COOH 0.163 Sulphocyanacetic.. CH2(SCN).COOH 0.265 Cyanacetic CH.2(CN).COOH 0.370 DERIVATIVES OF PRoPIONIC AcID SHOWING THE INFLUENCE OF VARIOUS SUBSTITUENTS UPON THE DISSOCIATION CONSTANT. Propionic CH;3.CH2.COOH 0.00145 6-Hydroxypropionic |CH,(OH).CH:.COOH 0.00311 CH;3.CH(OH).COOH 0.0138 Glyceric CH.(OH).CH2(OH).COOH 0.0228 Iodopropionic CH.ICH2.COOH 0.0090 Trichlorlactic CCl;.CH(OH).COOH 0.465 152 APPENDICES TABLE XVI. — Dibasic Acids and Some of their Substitution Products. (Ostwald.) Temperature = 25°. Substance. Formula. COOH.COOH Malonic (Walden)... CH2(COOH). Succinie C2H.(COOH).2 Glutaric C3:Hs(COOH )2 Pimelic CsHio(COOH).2 Dipasic UNSATURATED AcIps ILLUSTRATING THE RELATION BETWEEN CONFIGURATION AND DISSOCIATION CONSTANTS. Hyproxy DrrivaTives oF Drsasic AcIps. Succinic C.H,.(COOH). 0.00665 i-Malic C.H3;(OH).(COOH): 0.0399 Tartaric (d-, l-, r-) C.H2(OH)2. (COOH). 0.097 APPENDICES 153 TABLE XVII. — Benzoic Acid and Some of its Substitution Products. (Ostwald.) Temperature = 25°. Substance. Formula. 100 K. Benzoic (Bauer) CsH;.COOH ~ 0.0073 Cinnamic C.H;.CH =CH.COOH | 0.00355 o-Nitrobenzoic CsH4. NO2.COOH 0.616 p-Nitrobenzoic CsHs.NO2. COOH 0.0396 m-Nitrobenzoic CsH4. NO2. COOH 0.0345 m-Chlorbenzoic C.H,4.Cl. COOH 0.0155 o-Chlorbenzoic C.H..Cl. COOH 0.0132 p-Chlorbenzoic C.H,.Cl. COOH 0.0093 o-Hydroxybenzoic, salicylic.| CsH..(OH).COOH 0.102 m-Hydroxybenzoic C.H..(OH).COOH 0.0087 p-Hydroxybenzoic C.sH,.(OH).COOH 0.0029 Dihydroxybenzoic (2, 6)....| CesH3.(OH)2. COOH 5.00 Dihydroxybenzoic (2, 3)....| CsH3.(OH)2,. COOH 0.114 Dihydroxybenzoic (2, 5)....| CsH3.(OH)2. COOH 0.108 Dihydroxybenzoic (2, 4)....| CsH3.(OH)2. COOH 0.052 TABLE XVIII.— Phenol and Some of its Substitution Products. Temperature = 25°. Substance. Formula. 100 K. Phenol (Walker) C.sHs.0OH 0.000000013 o-Nitrophenol (Bader) CeHy.NO2.0H /|0.000043 m-Nitrophenol (Bader) CsHy.NO2.0H /|0.000012 p-Nitrophenol (Bader) CsHi.NO2.0H |0.0000089 Dinitrophenol (1, 2, 6) (Bader).. .|CsH3. (NO2)2.0H 0.0174 Dinitrophenol (1, 2, 4) (Bader).. .|CsH3.(NOz2)2-OH|0.008 Dinitrophenol (1, 3, 6) (Bader).. .|CsH3.(NOz2)2.0H |0.0007 Dinitrophenol (1, 2, 3) (Bader). se CsH3.(NO2)2.0H 0.0012 Dinitrophenol (1, 3, 4) (Bader)... .|CsH3. (NOz)2.OH 0.0004 154 APPENDICES TABLE XIX. — Dissociation Constants of Some Organic Bases. (Bredig.) Temperature = 25°. Substance. Formula of the Base. ALIPHATIC AMINES. Methylamine : ~ 0.050 Ethylamine ; 0.056 Dimethylamine : 0.074 Diethylamine : 0.126 Trimethylamine 0.0074 Triethylamine 0.064 K=1.6X10—-4 C;-H;NH;0H K=1.1 < 10-10 C.sH;CH.NH;0H 2.4x10-5 o-Nitraniline (Farmer). ...| CsH4NO,.NH;0H 610-4 m-Nitraniline CsHsaNO.NH;OH 4X 10-12 p-Nitraniline CsHz.NO,NH;0H 1.210-3 REFERENCE TO THE LITERATURE. Ostwald, Z. fur Phys. Chem., 3, 170; 31, 433. Bredig, Z. fiir Phys. Chem., 13, 289. Walker, Z. fiir Phys. Chem., 4, 319. Walker, Z. fiir Phys. Chem., 32, 137. Bader, Z. fiir Phys. Chem., 6, 289. Bauer, Z. fiir Phys. Chem., 56, 218. Walden, Z. fur Phys. Chem., 8, 433. . APPENDIX E. HYDROLYSIS OF SALTS OF WEAK ACIDS AND WEAK BASES. TABLE XX. Temperature = 25°. (From Walker’s Physical Chemistry.) Per cent. of Substance. Formula. hydrolysis. Salts of Weak Acids x Potassium phenolate Potassium cyanide Sodium tetraborate Sodium acetate NaC2H;302 Hea? Weak Bases - 10 Aniline hydrochloride CsHsN H3.Cl p-Toluidine CH;C.H,N H3.Cl o-Toluidine CH;CsH.NH;.Cl NH2CONH;.Cl Concentration 39 o-Nitraniline hydrochloride ..| NO.CesH,NH3.Cl m-Nitraniline hydrochloride. .| NO2C;H,NH3.Cl p-Nitraniline hydrochloride ..| NOzCsH,NH;.Cl Acetanilide hydrochloride... .| CsHs.N(COCHs) H2.Cl 155 APPENDIX F. LIST OF APPARATUS NEEDED TO PERFORM THE EXPERIMENTS IN THIS OUTLINE. (ORIGINAL OUTFIT.) RETURNABLE ARTICLES. 1 Adapter, bent. 2 Bottles, vial-mouthed, 1000 c.c., plain. 4 ovr Wide 250 cau 2 7 evaiale < 200. C.0:aie aan 1 Bucket, small, granite ware. 2 Bunsen burners. 1 Calcium chloride tube, straight, 18 cm. 1 u ? S 2oeme 2 Clamps and attachments. 1 Condenser, Liebig’s, 55 cm. 1 Cork borer, set of 5 and handle. 1 Crucible, iron, 6 cm. 1 Crucible tongs, iron. 1 Cylinder, grad., 100 c.c. 1 Desiccator, Scheibler’s, 10 cm. with side tube. 1 Dropping-tube, cf. § 16. if Evaporating dish, 7 cm. 1 » 10 cm. 1 a " 12 cm. 1 Filter pump a attachment. 2 Flasks, flat bottom, 30 c.c. 4 Flasks, flat bottom, 100 c.c. 2 4 300 c.c. Pe ee *: “2 500 c.c. 1 Haak es Be LOO Ge 1 ” ~~ round bottom, 500 c.c. 1%, 2) filtering “20a: AE ee distilling, 15 c.c. ) Ea 30 ¢.c. evans Ms 506.6: be e 150 c.c. 1 Fractionating-column, cf. § 1. 156 APPENDICES 157 RETURNABLE ARTICLES. 2 Funnels, 65 mm. 1 Funnel, 10 mm. fee Buchner, 64 cm. Lie 677 dropping, 60 c.c. Dee separatory, 250 c.c. 4 Glass plates, 4 x 4 inches. s 1 Mortar and pestle. 1 Nest of beakers, 50 c.c. to 600 c.c. 1 Pinch clamp, Mohr’s. 3 Rings, iron, three sizes. 1 Sand bath, sheet iron. 1 Screw clamp. 1 Spatula, porcelain, 10 cm. 1 Stand, iron, small. 1 Stand, iron, medium. 24 Test-tubes, 160 x 15 mm. 1 Test-tube holder. 1 Thermometer, 360°. 1 Thistle tube. 1 Tripod, iron. 1 Tube, hard glass combustion, 25 cm., cf. § 20. 1 Watch glass, 50 mm. eae oo TOM, jd a ” 100 mm. 1 Water bath. 1 Set of weights, 10 mg. to 50 g. NON-RETURNABLE ARTICLES. 1 Clay triangle. 1 File, triangular. 1 File, round. 5 ft. Glass rod, 4 mm. 5 ft. Glass tubing, 6 mm. 1 Package of filter paper, 9 cm. 1 ft. Pure gum rubber tubing, ¢ in. 9 ft. Rubber gas tubing. 1 Sponge. 1 Test-tube #rush. 1 Towel. 1 Wire gauze. 158 APPENDICES List oF SpecrAL APPARATUS USED ONLY IN ONE EXPERIMENT. Asbestos paper, thin, § 18. Bath, Wood’s metal, § 57. sna terayt Baa es ig Fractionating-column, special form, § 28. Galvanometer, § 22. Kipp’s apparatus, § 178. Manometer, § 120. Pipette, 5 c.c. grad. in 0.1 ¢.c., § 96. Platinum electrodes, § 22. 4 wire, fine, § 18. Sodium press, § 17. Soxhlet extractor, § 102. Two-liter flask, § 57. APPENDIX G. SOME SPECIAL APPARATUS FOR PREPARING REAGENTS. GASES. a. Kipp’s Apparatus. Many gases (CO, HS, H, ete.) which can be prepared by the action of liquid reagents upon solids, may be made in small amounts for laboratory uses by means of a Kipp Generator. The solid in large pieces rests upon the Zé p> | | Fig. 24. Kipp’s Apparatus. shoulders of the middle glass compartment. The liquid reagent, usually water or acid, is poured into the upper glass globe, from which it flows to the bottom compartment, and thence to the solid. The upper chamber serves as a reservoir to accommodate the liquid which, by the pressure of gas evolved after the flow of gas has been stopped, is forced away from the central and lower compartment. The gas generated passes through the stop-cock to appropriate apparatus containing reagents for 159 160 APPENDICES washing it or drying it. For this purpose, it is convenient to use a Drechsel Wash-bottle charged either with wash liquid or with drying agents. Large U-tubes charged with drying or ey | | SLAM FE SRF ERE BOTA SS Cre Fig. 25. Dropping-generator. purifying agents are frequently desirable; e.g., calcium chloride or phosphorus pentoxide to remove water vapor, soda-lime to remove acid vapor, lead acetate on glass beads to remove hydro- gen sulphide. When considerable quantities of such gases are required, it is APPENDICES 161 now customary to prepare them in large, specially constructed generators, or to supply them from cylinders of compressed gas (oxygen, hydrogen, carbon dioxide, etc.) connected with pipe systems. By means of a pressure reducing device at some central supply station, the pressure at which gases from such cylinders are delivered can be regulated and set as required. b. The Dropping-generator. A very convenient form of gas generator, known as the dropping-generator, devised by Mr. Freas* of the University of Chicago, has proved very useful in preparing many gases in which liquids must be added during the process, and must be admitted to the generator flask while the gas, under some pressure, is being evolved. The following table will illustrate some of the reactions which may be carried out with the dropping-generator. TABLE XXI.. Reagent used in the Dropping-generator. Reagent used in the Flask. ley HCl (dil.) NaHCO; H,.O Na2O2(oxone) HCl (dil.) FeS (powd.) HCl (dil.) Zn (dust) NaNOz (sat. sol.) HCI (dil.) + FeCl, (heat) NaNOz (sat. sol.) NH,.Cl + H:20 (heat) HCl (dil.) HCl (conc.) H2SO, (conc.) H.O 2 i OH (abs) alcohol) | H4PO, (ap. gr. 1.73) (heat) Bra ted HO A dropping-funnel of the usual kind is modified by providing it with a side tube of glass which connects the space above the liquid in the funnel with the interior of the generator flask, thus equalizing the pressure at the two places while the liquid, regu- lated by a stop-cock, is allowed to flow into the flask. A second stop-cock sealed in the pressure equalizing tube must be closed when it becomes necessary during the operation to pour more * Thomas B. Freas, School Science and Mathematics, February, 1907. 162 APPENDICES liquid into the funnel. The gas passes from the flask through the annular space between the two tubes at the bottom of the dropping-generator, where an exit tube conducts it to a wash- bottle. This device greatly facilitates the setting up of apparatus, especially for lecture demonstration, since it does away with the usual cumbersome connections made by means of three-holed stoppers. SOLUTIONS. a. The Dissolving-tube. The problem of making filtered solutions of difficultly soluble crystalline solids — such as mercuric chloride, copper sulphate, potassium dichromate, silver nitrate, etc. —is one which causes considerable oe inconvenience when time is an item. A simple y device suggested by Mr. Freas* of the Uni- versity of Chicago is very useful for such pur- poses. It permits of the making of filtered solutions of any desired strength up to satu- rated solutions. The weighed solid is placed on a filter-plug of cotton or of glass-wool in the chamber of the dissolving-tube. An ordinary 2-liter acid bottle contains the measured solvent, which should fill the bottle to a point sufficiently high to permit enough water or liquid to be drawn up to fill the dissolving-tube; at the same time sufficient water should be left in the bottle to Fig. 26. The cover the end of the wide tube which leads to Dissolving-tube. the side tube of the dropping-tube. A notch cut in the cork of the bottle permits air to enter. ji When the materials are ready, the dissolving-tube is closed with a rubber-stopper which fits it air-tight. By means of a stop-cock inserted in this stopper, air is drawn from the apparatus until the liquid has risen and filled the dissolving-tube to a point slightly above the opening of the side tube. When the stop-cock is closed, the denser liquid around the solid will fall to the bottom * Thomas B. Freas, School Science and Mathematics, February, 1907. iti APPENDICES 163 of the bottle through the longer tube, and will thus displace pure solvent at the surface of the liquid in the bottle. A continuous flow of the liquid will begin, and will not cease until all of the solid has disappeared or the solution has become saturated. b. The Soxhlet Extractor (see page 91, Fig. 21) will be found very serviceable when it is desirable to make a separation of two or more substances by means of a limited amount of solvent. The mixture to be extracted is placed in an extraction thimble * indicated in the illustration by dotted lines. The solvent is poured into the flask and heated until it boils. The vapors pass from the flask through the wide tube to the left in the illustration, and are condensed in the Liebig’s condenser at the top. The liquid then drops upon the mixture in the thim- ble. When the level of the liquid in the main compartment reaches the level of the bend at the top of the small side tube at the left in the illustration, the solvent with some dissolved substance syphons back into the flask. This action continues until the mixture in the thimble is completely extracted. * Extraction thimbles for this purpose are made by Schleichert and Schill, and may be purchased through any large dealer in chemical supplies. APPENDIX H. LISTS OF GASES, LIQUIDS, AND SOLIDS USED AS REAGENTS FOR ORGANIC CHEMISTRY. The following lists include the reagents needed to perform all of the experiments included in the outline. Whenever a reagent is used more than ten times in the outline, that is in more than ten different sections, no section numbers are given in the lists. In all other cases the numbers of all sections in which each reagent is used are printed in bold type. The letters S.R. after a name indicate that it is not advisable to put that substance on the side-shelves. Such substances are either dangerous or costly. They may be set out for the par- ticular experiment, or better still, in many cases, they may be distributed to students at the storeroom. The concentrations of the solutions are given in most in- stances. In order that the student may be informed of the approximate strength of each solution he uses, the solutions have been made of some definite normality, usually normal (N.), molar, half-normal (3 N.), or tenth-normal (75 N.). In a few special cases, the concentrations are expressed in terms of per cent. The number in parentheses following the symbol desig- nating concentration is the weight or volume of a substance required with water to make one liter of the solution. Sat. = saturated. In the case of hydrates, the calculations are based upon the use of the commonest commercial hydrate. Unless this is the case, the formula of the substance used will be given. It is desirable to place on the labels of the reagent bottles all of the information given above. This will inform the student, as well as the person who makes the solution, as to the exact nature of the contents of each bottle. When the experiments to be performed have been decided upon, it will be possible to exclude from the list of reagents for the shelves all materials which are shown in the following lists to be required only for experiments outside of those chosen. 164 = ee > ae = APPENDICES 165 GASES. SECTION. LE 2 Seen UNE 2 130, 137, 163, 173 Chlorine. . [Sad cate 81 Hydrogen . Re ee OH Te at or a chloride . Ra ee a ik Neh ee S04 197 ts sulphide ......... Pe arte Gay ae hs RAN TOR EO EE OOTP gs bay kde Seed as. Cie a eae ety 108 LiqUuIDS AND SOLUTIONS. (600 c.c. narrow-mouthed bottles.) Acetic acid, glacial...... 32, 38, 94, 108, 115, 117, 165, 166, 167 ¢" ” dilute, 6 N., » (220. C.8, of 80 per cent. FY ” anhydride. . ; . .86, 141, 143 ” ethyl ester . iy e455 Acetone... nee sai ois: 28, 29, 31, 32, 50, BT, 93, 170 Acetoacetic ethyl e ester . 2. epee ’ 87, 168 Acetylacetone .. ES CR RRO SA pee ee acaba aad 8 Acetyl chloride. . MIR Se Sy ON rar bin a, ancien, AL LOS Alcohol, 95 per cent. Aluminium chloride, #5 molar, (7% N.)................96, 105 44 Pe hoe eA laa tiath dees abd cod hse 9 ae Manon cnioride, 4N.; (213.5). .............4....¢, Ol, 161 4 ferric sulphate, 10 per cent. .......... 65 4 hydroxide, 6 N., (400 c.c.).... 7, 45, 74, 78 ? a com’l., 7 N. Amylene. . MNRONE ee Le tes, 0 og gl TY Ue 5 abla nse Dao 6 Amyl aleohol . a eet Soe ORE eee Mien ae Gok, PER oe ee Ui | Amy] nitrite. . 109 1 a 106, 108, 112, ‘115, 120, 125, 141, 154, 172 Aniline solution, sat., 3 N. ooo, Sop aed ]-Arabinose. . RN U8 ae EEE hic dike ip Coke eS Barium chloride, 7; molar, (4 N.), (24.4) ................ 96 Benzaldehyde ............... 29, 30, 134, 135, 141, 145, 150, 152 Benzene, benzol . BRA SiNe Sachs 97, 98, 99, 100, 138, 178 Benzoyl! chloride. . ike .11, 60, 61, 129, 138, 143 Brom benzene, cf. phenyl ‘bromide. — 166 APPENDICES SECTION. Bromine, element . Re .51, 66, 157, 165 Bromine solution, 5 per cent. in : carbon tetrachloride . 6, 97, 127 Bromine water, sat., 3 N., (15 c.c.).. 0, 0s 88, “78, 127 Butyl alcohol, Ra Ae pectics (0s Uneeseiamee Meee Calcium chloride, 7) molar, (3 N.), (21.9 cryst.) ..64, 65, 95, 96 i hydroxide, lime-water, sat., #5 N. (2 as CaQ). Carbon disulphide .;..., ...:<4,./.<.0 eee 74, 76, 138, 162 Chloroform arava. ce oe ee eee . A, 8, 45, 52, 58, 63 Chromic acetate. Ree er SS: see re at Cupric sulphate, N ., (125) . eee oa ra 61, 79, 87 Diethylamine, S.R...............2.22 eae 53 Dimethylaniline .. Pee ..108; 113, 117, 121, 149) 152 Dimethyl sulphate, ‘Ss. R.. ase Wee 78 128 Ethylammonium ares go N., Ay a oo een ene 8 Ethyl bromide. . Lee Se Ethyl ether, absolute ve edie e seein in a ecu) pale dll eine aga ena Ethyl iodide, 8.R. cece vele bled dalle 0 cle) gct Wilestan aan as Ethyl malonic acid, SR. . Leech nee Pete es Ferric chloride, N., (90). Ferric hydroxide, colloidal sol. ...............+.--.+--- 985 Ferrous sulphate, 75 N. .44, 83 Fehling’s solution. . 26, 30, 89, 90, 91, 104, “120, 150 Formaldehyde, formaline, 40 per cent coast eee ee 22, 94, 149 Glycerol, glycerine ..:...:...+--+c4+00 «sie hoy Gey Ogee amen Hydrochloric acid, C.P., conc., 13 N. hae “dil, ON. , (467 c.c.) 4 Use? ro N eke ae er 96 Hydrochlorplatinic acid, S.R., 10 per cent.. .. ..52, 53, 105, 172 Hydrogen peroxide, 10 vol Re a 50 Hydroxylamine pei) 10 per cent... she aE g-Hydroxybutyric acid, 8.R. re sin al Lee Iodine solution (11:5 KI: 15 ane weeee ee el, 45, 92 FeO PE DY Cn ea ; eee Isopropyl] iodide, S.R. . MPI APPENDICES 167 SECTION. CE ARMM os Gin) ig ein g's b.6 64 dp bo nid eos Lead acetate, N.. Ree sa ee Ligroine, boiling-point 40°-60° . ted ware COP SL OS Litmus, neutral. Magnesium sulphate, ee Pe een, Ee AT EO Mercurie chloride, sat., 4 Ga Fete Re Pe 34, 48, 82 Methy] alcohol.. i V2: p 19, 20, 22, 34, 35, 37, 48, 101, 102, 164 ” iodide, S. R. eee oes 43, 164, 171 MPO SOUIGION 6.2, ee ie ce hs ce eve we ev vey OL a, oe nalts a eds pwd wae LAG Sa RERC NEV OOMIUITIO Fo. yh. och hy care ice ne ep nn we wend LOS a-Naphthol, 10 per cent. in chloroform. ................ 88 Pirekoruiurace, N., (145)... ..6.....--..- 62 me cero oouc,, ©. P.,16 Ni... cn... ek ces 99, 100, 130, 131, 151 Nitric acid, dil., 6 N., , (B82 € C.C. a Nitrobenzene aoe ones a1013 102, LO0bpeL (2 Nitroethane, S.R.. of TONER Ste ree a 48 Petroleum ether, cf. ligroine. Phenolphthalein sol., (1 g. + 500 c.c. se Ee cies horas 36 Phenyl bromide, brombenzene ....... HS Le Phenylhydrazine.. hoes 32, 93, 139, 140, 168 Phloroglucinol, 1 per cent. sol. . pcre 20 Phosphoric acid, sp. gr., 1.73, 46 N.. a ieee te tp) 61 Phosphorus trioxide, S.R.. ee eae we Platinic chloride, cf. hydrochlorplatinie acid. Potassium bromide, 3 4.N., (59.5).. rs terse .8, 97 o oa : PVCS: fia ko een cioike yo 91, “158, 171 7 ferrocyanide, 10 per cent. re ere 65 ie hydrogen sulphide, 33 per ‘cent, Mra) ee as iodide, 3 N., (83). . EKO ET oy 9 ich x Pon nitrate, 4 N,, (50. aie uA 22 ‘J permanganate, iN.,, (79) . As a ‘66! 68, 97, 121, 141 4 ae 10 per ene AG aaa to N. ie ees. 65 Pyridine. . : a as Aes TOU EL Resorcinol, resorcin, 0.5 per cent. sol................... 19 Meat 168 APPENDICES Schiff’s reagent. . Silver nitrate, 4 (42. a Sodium acetate, N., (136 eryst.) bromide, 7. vs molar, (75 N.), (10. a 4 carbonate, N., (53 aalivcrodca £: chloride, 75 molar, (ao N.), (5. 85)... 9) 9 ”” hydrogen phosphate (NasHPO,) molar . sat., 6.5 N., (322))) + ED, SECTION. . .29, 30 8,9, 22, 23, 34, 36, 43, 81, 82, 84, 134 Soap solution, teal dv abnalce +s bt se0o 95 a5 121, 127, 134 ” hydrogen aoe (bisulphite, 40 per cent, AY 28, 134, 146 ¢ hydroxide, 7 to N.; (4.0) . 24 iodide, 7's molar, te N..). 332) di sulphate, 75 molar, 3 + N., (82. mie Sulphuric acid, cone., C.P., 36 N., 4 rene C.P., 6 N;, (167. C.C; aay Tollen’s ecru eee Toluene . xh Turkey-red oil I-Xylose 5 per cent. sol. ...... Zinc chloride, 4 SOLIDS. (250 c.c. wide-mouthed bottles.) APeLSIOIGe!, «0 an ee Acetanilid....... 2.0.0.0) 45. 0.521 ee Albumin 2. oi. oe ee ee Alizarin-paste . Aluminium chloride, anhydrous, § S, R. oy ea . ; eo ‘i a 1 8-Amino-naphthol, 3,6- mae acid, ae mene meee ss - Ammonium chloride. . $ oxalate. ... 3 Aniline hydrochloride 3:2... |... eee Anthracene ... RETR ue Antimonious oxide........ Arsenious oxide, powd... N., (68 cryst.).. sulphate... 2. 6.2.2... 126, 127, 131, 135 i BB a80 .. ..98, 167 161 89 105 a 167 85 36 APPENDICES — PENANG. 6... .. ss - Benzoic acid . Bleaching-powder, } Ib. can, S.R............. Caffein, S.R.. Bien Bde: ois c chloride, fused sticks. chloride, porous fused. oxide, quick-lime Sepa 9 9 Cane-sugar, cf. hl Casein.. Charcoal, “animal Chloral hydrate... 169 SECTION. ells peeves 57 80 7 ..2, 52, 158 ey AS, 108, 130 Chromic anhydride com 7 ; 3 ; x 7 Derk! ice Re tae Ce Cloth, cheese-. . 9) Copper turnings.. hte ee a ea SOnGO Ted... 5... se ) Cotton. Cupric acetate .. . »” chloride. . ” oxide, powd. ” sulphate, anhydrous te Se ee ee ” ” eo Cyanuric acid .. Dextrin....... Diethyl tartrate... Dimethyl glyoxime .. 3,5-Dinitrobenzoic acid. . Diphenylamine .. .. Pereroreroride, ANUYCTOUS....... 2.0. 6. 2 ee eee ee eee Ferrous sulphate..... cn 1h 2 eerie PnCHSIMe... 6. ..c... d-Galactose ... Gallic acid... mordanted i in strips. Saantond bie Pe OSpere cc osc. e 5s. 63 136 170 APPENDICES Gelatin. «oo be ivck web in ee aso eee Gelatin plates. . O-GIUCO8C soi vse alg ole pide eis ele 0 ove clale pt grate nae Ghartin. oo oN ec sl cw eC a hela ble Glycogen iia. eis se ea ee ce ve oa be te gern Gum arabic; . 2960s oe deen Ds ek Hydroxylamine hydrochloride, 8.R LOCING! 5) ee dees Indigo, natural....... Iron filwigg (5) 3 oa Lactose, appt pai Lead chloride. . ” dioxide. . Litharge, lead monoxide. . Litmus paper. Magnesium turnings (Grignard)... Malachite green . .. Maleiec acid, S.R.. 6.6. cs. 0s oe ee Maltose, malt-sugar... ........... Manganese dioxide, powd. .... .. .. «5: 92: iee ee dzMarinose.. 2s. «ago Mercury, metallic... ....0, ¢..., +. 2<0eeee Mercuric chloride, powd. :....... 2. .203ay ae eee Mercurie cyanide:)\o55-.ne eee Meta-toluylenediamine. . Methylamine hydrochloride, SR. . s rs e Me ay ek reenter sey ~ Methyl violet . Methylene blue... . ae . oa eee Milk-sugar, cf. Lactose. Monochloracetic acid... . Naphthalene ...... a-Naphthol. . B-Naphthol . .. a-Naphthylamine. . uae Ae ewes SECTION. 96, 148 ..88, 91, 92 Be a! 7, 31,197, 138 119) 14, eee .. ..158, 169 97 90 5 oe alae ...149, 153 34 Pee 15, 102, 174 151 ee eee ek wae 113, 122, 163 die 113, 160, 163, 164, 165 113 APPENDICES 171 SECTION. 6-Naphthylamine. . EN Bee Res en one. Sas eble Naphthionic acid. . fee rg pe cos ae ge at Bs o-Nitrobenzaldehyde, S.R.. Soe rey aren ae owen WL0 p-Nitrophenylhydrazine, S. ita Dt ee ee ure foe eek aise ooo vals vee eka aie 04, 66,155 Been mee wee. -.- SIDR SALE EIN AON aA eee REY Paranitraniline . eee eis oR et mo Ne LOT es LIL Phenacetin, com’l. 132 Phenol, carbolic acid . 113, 122, 127, 128, 129, 130, 131, Toe 156 m-Phenylaminediamine. . he See LG Phosgene in toluene, 20 per cent, . hee Peng et ht SLMS ef Phosphorus, red. . Pieter ahah a cr UeAO RT ss pentachloride, S.R.. ett en onteler Loe a pentoxide, S.R... ile eet pane coer EN Ue MCU OTIG oki s cna vcu capes vcccecescveccs 156 Ot ee ee Potassium carbonate, anhydrous « se Ae .59, 128 # cyanate. . Me Ot 72, 7, 94, 133 g cyanide, 98 per pent. Ne 20, 94, 145, 150 ae dichromate, granular . Seabi e be a0, on, 125, 141 “ ferricyanide . oe SAN RE POEM Rae eT! CE LANs, de hydrogen tartrate . LAR ea ASE ena de 85 id hydroxide . . a eas eee ..8, 43, 51, 54, 164 ni iodide . 109, 111, 112, 141, 144 3; thiocyanate (sulphocyanate). . ee 65, 75 NN te RR os lags Gace ea Seem ies 160 Re ee 0) ok 6 Lbs oo Neca ha tale sees oat. Led Resorcinol (resorcin) ........... MelIS A122 0127 peel Rosaniline . oe ey Rochelle salt, ef. sodium potassium tartrate. Sand. . EE ea PN ie iiad sie oe Meee Silk, white. . Mtr eet eS Poe. a ee, ale A eee LL Silver nitrate, Ea i Ree ces 49 Soda-lime. . Ee ee Pee 40, 44 Sodium, metallic, ‘cape @ Sateen Tk. 17, 22, 44, 48. 59 - acetate, cryst. Ke a 109, 111, ‘112, 113) 114, 143 172 APPENDICES SECTION. Sodium, acetate, fused . a 11, 36, 41 acid carbonate, cf. sodium n hydrogen carbonate. ” carbonate, anhydrous. . .. 187, 159 ” chloride, CP. ” chloride, common salt fs formate. . . .04, 37, 64 ” hydrogen carbonate... io arn ” hydroxide . ...89, 67, 101, 105, 110, 111, 117, “127, 130, 144, 169 ”” methyl sulphate. . Soe te ee we Nitrite fe 47, 111, 112, 116, 118, 119, 120, 121, 127, 136, 141, 171 7 peroxide . cones ws 144 ” potassium tartrate .. . . .26, 84 ” sulphate, hydrate. . 98. 159 Stannous chloride, mee Se a Starch. . Sugar (cane-sugar).. Sulphanilic acid. . Tannie acid 0... 0000 0, eee Tin, granular..... p-Toluidine.... Uren 32st es Oric avid... 2 eee Wood Splints °*.) 2h. e aoe Woolen yarn, white........:..... Zinc dust.. Zinc chloride, anhydrous Re ......110, 117, 120, 121, 136 ..91, 92, 96, 109, 112, 134 88, 89, 90 117 ..148, 161 105 154 ..44, 77, 78, 79, 96 80 eee ..115, 161, 163 ..4, 103, 122, 153, 154, 157, 173 152 APPENDIX I. REAGENT BOTTLES AND RE- AGENT SHELVES. Borvr.eEs. For liquids, 500 c.c. tincture bottles of the type represented in the illustration are very serviceable. The wing stoppers are easily held between the fingers in the usual way while the reagent is being poured. Such stoppers are much to be preferred to NITRIC ACID 125 Fig. 27. flat stoppers for this reason. When flat stoppers are used, they are placed upon the shelf or desk, and in this way are frequently broken or returned to the wrong bottle. Glass-stoppered salt-mouthed iron-mould bottles, 8 oz. (250 c.c.), with hood tops have been found to be very convenient for solid reagents. The depression in the stopper facilitates the transferring of small amounts to tubes, flasks, etc. It has been 173 174 APPENDICES found that this form of reagent bottle induces economy in the use of solids. With the ordinary solid stopper it is customary to pour solids upon slips of paper or upon watch crystals, and to throw away the unused portion. LABELS. Narrow gummed labels with cations and anions, or with the common names, such as ethyl, methyl, cone. C.P., etc., printed separately, have been found to be a great convenience in labeling sets of reagents for various laboratories. With comparatively few different kinds of labels countless combinations can be made as required. Sets of such labels can be kept ready for use in small oblong pasteboard boxes arranged alphabetically. Labels may be made to stick firmly to glass by observing the following precautions: — Clean the surface of the glass very carefully with gasoline. Moisten the label thoroughly, and press it firmly against the bottle by means of a piece of blotting paper until all of the air spaces have been removed. If the mounted label, previously warmed, is quickly painted with paraffine heated almost to the boiling-point, and the excess of paraffine is rubbed off, the labels will last for years. REAGENT SHELVES. The illustration (Fig. 28) shows a type of reagent shelf which has been used successfully with elementary classes for a number of years. The dimensions of the shelves pictured are 72 in. high x 39 in. wide X 5 in. deep. By means of narrow (3 "in.) strips of wood at the sides and back, each bottle is provided with its own numbered compartment. These strips may be fastened so that all bottles, both large and small, shall set 1 inch back from the front of the shelf. If desired, the strips may be beveled in front, and may also be set back 1 inch from the edge of the shelf. This will leave a 1-inch margin in front of the bottles which will make it easy to keep the shelves clean. The bottles have very little free play. Asa result of this, they are always opposite the proper number on the shelf, and the reagent shelves as a whole always present an orderly appearance. APPENDICES 175 Fig. 28. Small brass stencils will be found convenient in numbering the compartments. The lower shelves have been made a little wider than the others in order to accommodate a number of small stone-ware jars with covers which have been used for some bulky solids; e.g., copper turnings, marble, nails, sand, etc. A shelf of the kind illustrated above will accommodate fifty students working at once. INDEX. Abbreviations, 2 Absolute alcohol, 8 Absorption curves, 82 plotting of, 83 Acetal of formaldehyde, 29 Acetaldehyde, 30, 32 Action of, on Fehling’ S solution, 32 Action of Schiff’sreagent on, 33 by the decomposition of lactic acid, 72 Polymerization of, 32 Reduction of silver nitrate by, 32 Resin formation with, 33 Tollen’s reagent with, 32 Acetamide, 45 Action of alkalies on, 46 Action of sulphuric acid on, 46 © in the preparation of methyl- amine, 49 Preparation of, from acetic ethyl ester, 45 Use of, in preparing acetoni- trile, 46 Acetanilide, Preparation of, 94 ' Action of sodium hydroxide on, Action of sulphuric acid on, 94 Acetic acid, 38 Action of chlorine on, 71 Action on aniline of, 94 Anhydride of, 43 as a solvent for bromine, 127 Chloride of, 42 Dissociation constant of, 151 Ethyl] ester of, 41 Salts of, 38 Acetic anhydride, 43 Action of alcohol on, 43 Action on diethyl tartrate of, 73 Acetic anhydride, action on water of, 43 in the preparation of benzoic anhydride, 115 to determine hydr oxy l groups, 43 ether, 41 Hydrolysis of, 41 Use of, in preparing aceta- mide, 45 Acetoacetic ethyl ester, 73 Action of ferric salts on, 73 Condensation of, with phenylhydrazine, 131 Copper salt of, 73 Tautomerism of, 74 Acetone, 34 Action of hydroxylamine on, 34 aa of phenylhydrazine on, 6 Action of sodium acid sul- phites on, 34 Condensation of, with benzal- dehyde, 34 in the preparation of chloro- form, 56 Iodoform test with, 21 p-nitrophenyl hydrazone, 36 Oxidation of, 34 Preparation of, from isopropyl alcohol, 34 Reduction of, 34 Acetonitrile, Preparation of, 46 Action of sodium hydroxide on, 46 Acetoxime, 35 Acetylacetone, 61 Action of ferric chloride on, 61 Copper salt of, 61 Acetyl chloride, Preparation of, 42 Action of aniline on, 94 177 178 Acetyl chloride, action of di- methyl aniline on, 94 Action of methyl aniline on, 94 in the preparation of acetic anhydride, 43 Reaction of, with alcohol, 42 Reaction of, with water, 42 Acetylene, Preparation of, 13 Action of bromine on, 14 Copper, 14 Flame of, 14 Acid splitting of acetoacetic acid, 71 Acrolein from glycerol, 60 Adipic acid, Dissociation con- stant of, 152 Air condenser, 19 Albumin tests, Nature of, 81 Alcohol acids, 72 Alcohol, 18 Ethyl, 8, 18, 21 Isoamyl, 21 Iscbutyl, 21 Propyl, 21 Alcoholic potash, 15 pees of,on brom benzene, 1 Action of, on chloroform, 57 Action of, on ethyl bromide, 15 Aldehyde. Cf. acetaldehyde ammonia, 30 Aliphatic hydrocarbons, 10 Alkyl cyanides, 66 Amides, 45 Amines, 48 Aliphatic, dissociation, con- stants of, 154 Aromatic, dissociation con- stants of, 154 Coupling of, with diazo com- pounds, 97 Aminoazobenzene, 98 by the rearrangement of di- azoaminobenzene, 98 Dyeing with, 99 Hydrochloride of, 98 Amino acids, 78 Aminoacetic acid, 78 INDEX ‘ Bem acid, Hydrochloride O ) Preparation of, 78 Salts of, 78 1,8-Amino-naphthol 3,6-disul- phonic acid, 99 p-Aminophenetole, 107 Action of ferric chloride on, 107 Hydrochloride of, 107 Ammonia gas, 31 Ammoniacal silver nitrate, 26 Ammonium ferric sulphate, 62 hydroxide, specific gravity of solutions of, 145 oxalate, 63 Reduction of mercuric salts by, 63 thiocyanate, 68 Amy] alcohol, 18 Amylene, Action of bromine on, 12 Amyl nitrite as a diazotizing agent, 95 Anhydride, Acetic, 43 Benzoic, 115 Nitric, 115 Phosphoric, in syntheses, 46 as a drying agent, 134 Aniline, Action of acids on, 92 Ager of acetyl chloride on, by the distillation of indigo, 131 Conversion into acetanilid, 94 Dissociation constant of, 154 in the isonitrile reaction, 57 in the synthesis of quinoline, 132 Aniline hydrochloride, 93 Action of hydrochlorplatinic acid on, 93 Conversion of, into benzene diazonium chloride, 95 Degree of hydrolysis of, 95, 1 54 Double salt with tin chlo- ride, 92 in the rearrangement of di- azoaminobenzene, 98 INDEX Animal charcoal to remove col- ored impurities, 94, 118 Anions in the precipitation of colloids, 80 Anisol, Preparation of, 105 Anthracene, 127 ao of toanthraquinone, 1 picrate, 127 Anthraquinone, 127 Antidiazotate of p-nitraniline, 96 Antifebrin, 94 Antimonious oxide in’ making tartar emetic, 73 Apparatus, Care of, 1 Lists of, 156 Special, for making reagents, 159 Aqueous vapor, Tension of, 142 1-Arabinose, 75 Action of Fehling’s solution on, 75 Aromatic acids, 115 amine salts, 93 Hydrolysis of, 93 compounds, 85 Asymmetric carbon atom, 72 Azo benzene, 90 Preparation of, from nitro- benzene, 90 Reduction of, to hydrazo- benzene, 91 dyes, 95 Azoxybenzene, 90 Bader 154 von Baeyer, 35 Barometer readings, Corrections for, 142 Bases, ae om ai constants of, 15 Bauer, 154 Baumé hydrometer, 143 Scale readings of, 143 Beckmann’s rearrangement, 112 Benzalacetone, 34 Benzaldehyde, 109 Action of air on, 109 Action of ammoniacal silver nitrate on, 109 179 Benzaldehyde, action of sodium hydrogen sulphite on, 109 Action of phenylhydrazine on, 109 Benzoin condensation of, 118 Condensation with dimethy]l- aniline, 119 Conversion into m-nitroben- zaldehyde, 109 Preparation of benzoic acid from, 115 Use of, in preparing dibenzyli- dene acetone, 34 Use of, in preparing mandelic acid nitrile, 116 Benzanilid from benzophenone- oxime, 111 Benzene, 87 Action of alkaline permanga- nate on, 87 Action. of bromine on, 87 Action of concentrated. phuric acid on, 87 Conversion of, into m-dinitro- benzene, 90 Conversion of, into nitroben- zene, 89 Diazonium chloride, 95 Reduction of, 95 Solution of, 97 Hydrocarbons, 87 Reaction of, with benzoyl chlo- ride and aluminium chlo- ride, 111 Sulphonic acid, 88 Benzidine, 91 Salts of, 91 Rearrangement of, 91 Use of, in making dyes, 99 Benzil, 118 Benzine, 88 Benzoic acid, 115 Dissociation 153 Detection of carbon and hy- drogen in, 10 Preparation of, 115 Anhydride, 115 Benzoblue, 99 Benzoin, Preparation of, 118 sul- constant of, 180 Benzoin, action of Fehling’s solu- tion on, 118 Benzophenone by Friedel and Crafts’ reaction, 111 Oxime, 111 Phenylhydrazone, 112 Benzoyl chloride, 115 Action on benzene and alu- minium chloride, 111 Action on ethyl alcohol, 18 Action on glycerol, 60 Action on glycol, 59 Action on phenol, 105 Peroxide, 115 Benzylamine, Dissociation con- stant of, 154 Bismarck brown, 99 Biuret from urea, 70 Bleaching-powder, Action of, on acetone, 55 Boiling-points, Correction of, 138 Determination of, 17 Boric acid, Dissociation constant of, 150 Bredig, 154 British thermal unit, 140 Definition of, 140 Comparison of, with other heat units, 141 Brom benzene, 15, 135 Action of alcoholic potash on, 15 in Grignard’s synthesis, 135 nitrosopropane, 48 Bromine with acetylene, 14 acetamide, 49 acetoxime, 48 benzene, 87 ethylene, 12 fluorescein, 120 6-naphthol, 127 phenol, 104 sodium nitroethane, 47 Biichner funnel, Use of, trated, 19 Bumping, Prevention of, 6, 49, 55 illus- Butyl alcohol, Tertiary, 18, 21 Butyric acid, Preparation of, 64 Dissociation constant of, 151 INDEX Cacodylic oxide, 39 Caffein, Action of nitric acid on, 70 Calcium carbide, 13 chloride as a drying agent, 16 malonate, 64 oxalate, 62, 63 oxide, 8, 16 tartrate, 72 Calorie, Definition of, 140 Calorific value, 141 Cane-sugar, 75 Action of Fehling’s solu- tion on, 76 Hydrolysis of, 76 Caproic acid, Dissociation con- stant of, 151 Carbocyclic compounds, 85 Carbohydrates, 75 Molisch’s test for, 75 Carbon, Tests for, in organic compounds, 10 dioxide, 161 disulphide, 67, 111 Carbonic acid, Dissociation con- stant of, 151 Casein, 80 Catylitic oxidation of methy] al- cohol, 25 Cellulose, Hydrolysis of, 76 Centigrade scale, 137 Comparison. of, with Fah- renheit scale, 138 Cheese cloth in dyeing, 122 Chloral, 33 hydrate, 33 m-Chlorbenzaldehyde, Prepara- tion of, 110 m-Chlor-a-benzaldoxime, 110 Stereoisomeric forms of, 110 m-Chlor benzoic acid, Dissoci- ation constant of, 153 o-Chlor benzoic acid, Dissocia- tion constant of, 153 p-Chlor benzoic acid, ’ Dissocia- tion constant of, 153 Chlorine, Action of, on acetic acid, 71 Chloroform, 31, 50 in isonitrile reaction, 50, 57 INDEX Chloroform from acetone, 57 Reduction of, to methane, 10 Chlorplatinate of ammonium, 50 of methylammonium, 50 of phenylammonium, 93 Chromic acetate, Lake of, with alizarin, 124 anhydride as an _ oxidizing agent, 34, 127 Cinnamic acid, Dissociation con- stant of, 153 Cobalt salts, Detection of nickel in, 61 Colloidal ferric hydroxide, 79 Colloids, Emulsion, 80 Suspension, 79 Congo-red, 93, 122 Copper acetylacetone, 61 Copper acetylene, 13 biuret, 70 cyanurate, 70 formate, 37 glycocollate, 78 oxide in the oxidation of or- ganic compounds, 10 sulphate, anhydrous, 8 Action of, on alkaline tar- trate, 73 turnings, 76 Correction of melting-points and boiling-points, 138 Coupling to form azo-dyes, 97 Cuprous acetylene, 14 chloride, 14 Making of, 14 in Sandmeyer’s reaction, 110 Crystallization, Purification of substances by, 19 Cyanacetic acid, Dissociation constant of, 151 Cyanates, 66 Cyanhydrine reaction, 116 Cyanic acid, 66 from cyanuric acid, 67 Cyanide by the action of sodium on nitrogen compounds, 66 Cyanogen, 66 Cyanogen compounds, 66 Cyanuric acid, 67 from urea, 70 181 Degree of dissociation, 150 Desiccator, illustration, 31 Detection of halogens in organic compounds, 15 Determination of melting-points, Government bulletin con- cerning, 21 Dextrin, 76 Diacetyl tartaric ethyl ester, 73 Diazoaminobenzene, 98 Action of ammoniacal silver nitrate on, 98 es of hydrochloric acid on, 9 Diazo-compounds, 95 Diazonium salts, 104 Diazotizing with amy] nitrite, 95 with nitrous acid, 95 Tests for completeness of, 95 Dibasic acids, 62 Dissociation constants of, 151 Unsaturated, 64 Dissociation constants of, 151 Dibenzylidene acetone, 34 Action of acids on, 34 Dibenzalacetone. Cf. Dibenzyli- dene acetone, 34 Dichinoyl! dioxime, 113 as a dye, 125 Dichloracetic acid, Dissociation constant of, 151 Dicyanogen, see Cyanogen. Diethylamine, Action of ethyl bromide on, 50 Diethylammonium Dissociation 154 Diethyl! ether, 22, 23, 24 Dihydroxybenzoic acids, Disso- ciation constant of, 153 Diketones, 58, 61 Dilution formula, Ostwald’s, 149 Dimethylamine from _ p-nitroso- dimethylaniline, 103 Dimethylammonium hydroxide, Dissociation constant of, 154 hydroxide, constant of, 182 Dimethyl aniline, Action on ace- tyl chloride, 94 Action of nitrous acid on, 101 Condensation of, with ben- zaldehyde, 119 Condensation of, with for- maldehyde, 116 Use of, in the preparation of helianthine, 99 glyoxime, 61 sulphate as agent, 67 m-Dinitrobenzene, 90 3,5-Dinitrobenzoic acid, 19 Dinitronaphthalene, 126 Dinitro-a-naphthol, 126 Dinitrophenols, Dissociation con- stants of, 153 Dinitrosoresorcinol, 113 Diphenylamine dyes, 102 Salts of, 93 Hydrolysis of, 93 Diphenylethane, Derivatives of, 118. Diphenylmethane, Derivatives of, 118 Direct dyes, substantive dyes, 122 Directions for the laboratory, 1 Disaccharides, 76 Dissociation constants, 149 Dissolving-tube, 162 Distillation, Fractional, 5 in vacuo, 58, 101 with steam, 56 Diureids, 69 Disazo compounds, 99 Double bond, von Baeyer’s re- agent for, 6, 65, 87. Drechsel wash-bottle, 160 Drinking water, Test for nitrites in, 99 Dropping-generator, 160 Gases generated in, 160 Dropping-tube, 22 Dulcin, p-phenetole urea, 107 Dyalysis of ferric chloride solu- tion, 79 Dyeing by precipitation, 122 . Experiments in, 122 an alkylating INDEX Ebullition-tubes, 5 Egg albumin, 80 Action of reagents on, 80 Electric current, Action of, on colloids, 79 Emulsion colloids, 80 Emulsoids, 80 Kosin, Preparation of, 120 Ammonium salt of, 120 Sodium salt of, 120 Ksters of benzoic acid, 18 of 3,5-dinitrobenzoic acid, 18 of nitrous acid, 47 of thiocyanic acid, 67 of isocyanic acid, 67 - Ether, Acetic, 41 Diethyl, 18 Phenyl methyl, 105 Ethereal salts, 18 Ethylammonium bromide, 15 hydroxide, Dissociation con- stant of, 154 Ethyl bromide, 15 Action of silver nitrate on, 15 Addition of, to diethylamine, 50 . Addition of, to triethyl- amine, 51 Kthylene, its preparation from alcohol, 11 Ethylene dibromide, 55 Conversion of, into glycol, glycol, Action of sodium on, 58 ester of benzoic acid, 59 Ethyl ester of acetic acid, 41 of acetoacetic acid, 73 of benzoic acid, 18 of diacetyl tartaric acid, 73 of 3,5-dinitrobenzoic acid, 20 of tartaric acid, 73 Ethyl iodide, 16 Action of light on, 16 — of silver nitrate on, 1 malonic acid, 64 mercaptan, 44 nitrite, 47 nitrolic acid, 45 INDEX Fahrenheit scale, 138 Fast green, 114 Fatty acids, 137 Fehling’s solution, Action of, on sugars, 75, 76 Action of,on acetaldehyde, 32 Preparation of, 32 Ferric chloride, anhydrous, 29 hydroxide, Colloidal, 79 oxalate ions, 62 Fibrin, Swelling of, 80, 81 Fluorescein, 120 Fischer, Martin H., 83 Formaldehyde, formalin, 25, 26, 27 Apparatus for preparing, 26 Condensation of, with di- methylaniline, 118 im milk, 27 Leache’s test for, 27 Resorcinol as a test for, 26 Formic cep as a reducing agent, 3 from lactic acid, 72 from methyl alcohol by oxi- dation, 38 from oxalic acid, 37 Salts of, 37 Fractionating-columns, 29 Freas, Thomas B., 161, 162 Freezing-mixtures, 140 Friedel and Crafts’ reaction, 111 Fuchsine, Dyeing with, 124 Fumaric acid from maleic acid, 64 Dissociation 152 Fuming nitric acid, Action of, on benzaldehyde, 109 d-Galactose, 75 Gallic acid, 116 Conversion of, into rufigallic acid, 116 Gases, Preparation of, by the dropping-generator, 161 used in the course, 165 Gelatin plates, Swelling of, 82 Glacial acetic acid, 39 d-Glucose, 75 constant of, 183 d-Glucose, Action of Fehling’s solution on, 75 Molisch’s test applied to, 75 Glucosazone, 77 Glutaric acid, Dissociation con- stant of, 152 Gluten, Swelling of, 80 Glyceric acid, Dissociation con- stant of, 151 Glycerol, 58 as a bath, 20 Action on copper salts in solu- tion, 60 Action of benzoyl chloride on, 60 Conversion into acrolein, 60 in the preparation of formic acid, 37 Glycerin, see Glycerol Glycine, 78 Glycocoll, Dissociation constant of, 151 Preparation of, 78 Glycogen, 76 Action of Fehling’s solution on, 76 Glycol, Ethylene, 58 ester of benzoic acid, 59 Preparation of, from ethylene dibromide, 58 Gram calorie, 140 Grignard’s synthesis, 21, 136 Gum arabic, 76 ape of Fehling’s solution on, 6 ““H’’ Acid, 99 Halogens, Test for, 10 Halogen alkyls, 15 acids, 71 Dissociation constants of, 151° Hantzsch, 107, 119 Hehner’s method of detecting formaldehyde, 28 Heat of combustion, 141 Heat units, 140 Helianthine, Preparation of, 99 Reduction of, 99 184 Heptylic acid, Dissociation con- stant of, 151 Heterocyclic compounds, 129 Hofmann’s mustard-oil test, 68 Hydrazobenzene, 91 Action of Fehling’s solution on, 91 ; from azobenzene, 91 Rearrangement of, to benzi- dine, 91 Hydrazones, 36 of acetone, 36 of benzaldehyde, 109 of benzophenone, 112 Hydrocarbons, 10 Acetylene, 13 Benzene, 87 Olefine, 11 Paraffine, 10 Hydrochloric acid, Specific grav- ity of, 146 Hydrochlorplatinic acid with methylammonium — chlo- ride, 50 Action of, on ammonium chloride, 50 Action of, on aniline hydro- chloride, 93 Action of, on quinoline hy- drochloride, 133 Hydrocyanic acid, Salts of, 66 Hydrogen, Tests for, in organic compounds, 10 Hydrogen peroxide, 72 sulphide, Preparation of, 161 Dissociation constant of, 150 Hydrol dye, 118 Hydrolysis of acetic ethyl ester, Al aniline salts, 93 acetamide, 46 acetanilid, 94 aromatic amine salts, 93 cane-sugar, 76 cellulose, 76 diphenylamine salts, 93 p-nitraniline salts, 93 nitriles, 46 INDEX Hydrolysis of salts of weak acids and bases, 155 soap, 39 sodium acetate, 39 starch, 76 Hydrophillic colloids, 80 Hydrophobic colloids, 79 Hydroquinone, 113 Diacetyl derivative of, 113 Hydroxy acids, Dissociation con- stants of, 151, 152 $-Hydroxybutyric acid, 72 Hydroxylamine, Action of, on aldehydes, 110 Action of, on ketones, 35, 111 as a reducing agent for copper salts, 14 6-Hydroxypropionic acid, Disso- ciation constant of, 151 Illuminating-Gas, 12 Unsaturated hydrocarbons in, 12 Indoamines, 102 Indoanilines, 102 Indigo, 122, 131 blue, Reactions of, 132 carmine, 132 Synthesis of, from o-nitroben- zaldehyde, 132 Interconversion of specific grav- ity readings, 144 Invert-sugar, 76 Action of Fehling’s solution on, 76 Action of phenylhydrazine on, (ib Iodine, Action on carbohydrates, 77 Detection of, in organic com- pounds, 15 Reaction with alcohol, 16 solution for iodoform test, 21 Iodoform reaction applied to al- cohols, 21 Preparation of, 57 Iodopropionic acid, Dissociation constant of, 151 Ionization constants, 150 INDEX Iron filings as a bromine carrier, 87 Isocyanide reaction, 57 Isopropyl! alcohol, 21, 34 iodide, 48 Isomerism, An illustration of, 40 Jara-Jara, 126 Kekulé’s formula for benzene, 87 hypothesis of linkings of car- bon atoms, 11 Ketones, Aliphatic, 34 Aromatic, 111 acids, 73 Ketonic splitting, 74 oe Rearrangement of, 11 Kilogram calorie, 140 Kipp’s apparatus, 159 Labels, 174 Laboratory precautions, 1 Lactic acid, Dissociation con- stant of, 151 Action of sulphuric acid on, 72 Lactose, milk-sugar, 76 Law of mass action, 149 Leache’s method of detecting formaldehyde, 26 Lead acetate in dyeing, 122 chloride in Grignard’s synthe- sis, 1385 dioxide as an oxidizing agent, 118, 119 formate, 37 Leuco-base of fluorescein, 119 malachite green, 120 pararosaniline, 120 Levulose, fruit-sugar, 75 Liebermann’s nitroso reaction, 103 Liebig’s condenser, Illustrations of, 5, 8, 9 Light action on ethyl iodide, 17 in accelerating oxidation, 63, 109 in causing rearrangement of maleic acid, 64 in processes of substitution, 13,41 185 Ligroine, Action of bromine on, 13 List of pada used as reagents, 65 solids used as reagents, 168 Lunge, Tables by, 144, 145, 146, 147 Lyophobice colloids, 79 Lyophilic colloids, 80 Magnesium in Grignard’s syn- thesis, 21, 185 to reduce azobenzene, 91 Malachite green, 119 Action of reagents on, 119 Maleic acid, Action of perman- ganate on, 65 Conversion of, into fumaric acid, 64 Dissociation constant of, 152 Malic acid, Dissociation con- stant of, 152 Malonic acid, Decomposition of, by heat, 64 Dissociation 151 Preparation of, from mono- chloracetic acid, 64 Maltose, malt-sugar, 76 Mandelic acid from its nitrile, 116 nitrile from benzaldehyde, 116 Manganese dioxide, 63 d-Mannose, 75 Manometer, 58, 101 Martius’s yellow, 126 Mass action, Law of, 149 Mauve, 103 Melting-points, 138 constant of, Correction of, determinations, 20 Menge, George, 21 Mercaptans, 44 Mercuric chloride as an oxidizing agent, 37, 63 in fuchsine preparation, 120 cyanide, Action of silver salts on, 66 186 Mercuric cyanide in preparation of cyanogen, 66 Metallo-organic compounds, 134 Methane from chloroform, 10 Methylal, 29 Action of sulphuric acid on, 30 Methyl alcohol, 18, 25, 26 amine solution, 49 aniline, 94 ammonium chloride, 50 hydroxide, Dissociation con- stant of, 154 cyanide, acetonitrile, 46 ester of formic acid, 40 iodide in Grignard’s reaction, 21 isocyanate, 67 mustard-oil, 68 orange, 99 salicylate, 116 thiocyanate, 67 violet, Dyeing with, 124 Methylene-amino-acetonitrile, 78 Conversion of, into glycocoll, 78 Methylene blue, 102 Milk, Test for formaldehyde in, 27 sugar, 76 Molar solutions with colloids, 80 Molecular rearrangement of ma- leic acid, 64 of diazoaminobenzene, 98 Molisch’s test for carbohydrates, Monatomic alcohols, 18 Monobasic fatty acids, 37 Dissociation constants of, 151 1-Monobrom-6-naphthol, 127 Monochloracetic acid, 71 Action of silver nitrate on, 71 Decomposition of, by carbo- nates, 72 Dissociation constants of, 151 Monomethylaniline, 94 Monosaccharides, 75 Mordants, 124 INDEX Mordanted cloth, 124 Murexid from uric acid, 70 Mustard-oils, 68 Naphthalene, 126 Dinitro, 126 a-Nitro, 126 Naphthionic acid, Coupling of, to form azo-dyes, 97 a-Naphthol as a reagent for car- bohydrates, 75 in the formation of azo-dyes, 96, 97 Nitration of; Martius’s yellow, 126 B-Naphthol, Action of sodium hydroxide on, 126 Coupling to form azo-dyes, 96, 97, 98 methyl ether, 126 1-monobrom derivative of, 127 a-Naphthylamine, Coupling of, to form azo-dyes, 97 8-Naphthylamine, Coupling of, to form azo-dyes, 97 Nef, J. U., 60 Nerolin, see 6-Naphthol methyl ether, 126 Nickeldimethylglyoxime, 61 Nitranilines, Dissociation con- stants of, 154 p-Nitraniline, Conversion of, into a diazo-salt, 96 Hydrochloride of, 93 Hydrolysis of, 98, 155 Nitric acid, Specific gravity of solutions of, 147 Nitrile, Aceto, 46 Mandelic acid, 116 Methylene-aminoaceto-, 78 Nitrites, Test for, in drinking water, 99 m-Nitrobenzaldehyde, 109 Nii in synthe- sis of indigo, 1 Nitrobenzene, 89 Preparation from benzene, 89 Reduction to azoxybenzene, 90 to azobenzene, 90 to aniline, 92 INDEX Nitrobenzoic acids, Dissociation constants of, 153 Nitroethane, Sodium salt of, 47 Nitrogen, Test for, in organic compounds, 45 compounds, 45 pentoxide, 115 Nitrolic acid, Ethyl, 47 Nitroparaffines, 47 a-Nitronaphthalene, 126 o-Nitrophenol, 106 p-Nitrophenol, Preparation of, 106 Nitrophenols, Dissociation con- stants of, 153 p-Nitrophenyl-antidiazotate of sodium, 96 “aa of, towards reagents, 9 p-Nitrophenylhydrazine, 36 Action of, on acetone, 36 p-Nitrosodimethylaniline, 101 Conversion of, into dyes, 102 Conversion of, into p-nitroso- phenol, 103 Hydrochloride of, 101 p-Nitrosophenol, 103 Nitroso reaction, Liebermann’s, 103 Nitrous acid, Dissociation con- stant of, 150 Non-electrolytes and swelling of colloids, 82 Note-book, 1 Oedema, 83 Oil bath, 134 of wintergreen, 116 Olefines, 10 compared with paraffines, 12 Osazone of d-glucose, 77 Ostwald’s dilution formula, 149 Oxalic acid, 62 Action of concentrated sul- phuric acid on, 63 as a reducing agent, 63 Calcium salt of, 62 Complex-ions of, 62 187 Oxalic acid, Preparation of, from formic acid, 62 Dissociation constant of, 152 in making para-rosolic acid, Oxidation and reduction cell, 28 of ethyl alcohol, 18, 30 of anthracene to anthraqui- none, 127 of acetaldehyde by silver ni- trate, 32 of isopropy] alcohol to acetone, 34 of methyl alcohol, 25, 26, 28 Oxime of acetone, 35 of benzophenone, 111 of m-chlor benzaldehyde, 110 Oxygen, Preparation of, from oxone, 161 Paraffines, 10 Paraformaldehyde, 25, 27 Conversion of, into methylal, 29 Parafuchsine, pararosaniline hy- drochloride, 120 Paraleucaniline, 120 Pararosaniline, 120 Perkin, 103 Peroxide, Benzoyl, 115 Petroleum ether, 12, 87 Action of sulphuric acid on, 87 p-Phenetole urea, 107 Phenol, Action of bromine on, 104 Action of sodium hydroxide on, 104 Action of ferric chloride on, 104 Action of nitric acid on, 106, 107 popping of, to form azo-dyes, Conversion of, into picric acid, 107 Conversion of, into anisol, 105 Conversion of, into phenyl ben- zoate, 105 Dissociation constant of, 153 188 Phenol, Preparation of, 97, 104 Use of, in making phenol- phthalein, 120 Phenolphthalein, 39, 120 Phenylacetic acid, Dissociation constant of, 151 Phenylammonium chloride, 93 Phenyl benzoate, 105 m-Phenylenediamine in the prep- aration of Bismarck brown, 99 Phenylglucosazone, 77 Phenylhydrazine, 77, 101 Action of Fehling’s solution on, 101 Condensation with acetoacetic ethyl ester, 131 Hydrochloride of, 101 in the preparation of hydra- zones, 36, 112 Preparation of, 101 Phenyl magnesium bromide, 135 methyl ether, 105 Phloroglucinol, 27 Phosgene in the preparation of urea, 69 Phosphoric acid, in the prepara- tion of acrolein, 60 in the preparation of ethy- lene, 55 Phosphorus, red, 16 as a chlorine carrier, 71 pentachloride in the Beck- mann’s rearrangement, 112 pentoxide, Action of, on aceta- mide, 46 trichloride, Action of, on acetic acid, 42 Phthaleins, 120 Phthalic anhydride, 120 in the preparation of fluores- cein, 120 in the preparation of phenol- phthalein, 120 Picric acid, 107 addition product with anthra- cene, 127 as a dye, 125 Piloty, 48 INDEX Pimelic acid, Dissociation con- stant of, 152 Platinum as a catalyzer, 25 chloride, Action on amine salts, 50 Polyatomic compounds, 53 alcohols, 58 Polyazo-dyes of benzidine, 99 Polyhalogen compounds, 55 Polymerization of acetaldehyde, 32 of cyanic acid, 67 Polysaccharides, 76 Potassium acid sulphate, 60 carbonate, Action of, on ethy- lene dibromide, 58 cyanate, 66 Conversion of, into methyl isocyanate, 67 cyanide, 66 in synthesis of organic com- pounds, 64, 66, 67, 78, 118 dichromate, 18, 30, 57, 122 ferricoxalate, 62 complex-ion of, 63 ferricyanide, Complex-ion of, 62 phenolate, Degree of hydroly- sis of, 1 permanganate, Action of, on benzene, 87 Action of, upon olefines, 12 Oxidation of benzaldehyde by, 115 Oxidation of oxalic acid by, 63 with maleic acid, 64 thiocyanate, 67 Precautions for the laboratory, 4 Precipitation of colloids, 79 Pressure, Correction of baro- metric, 142 Primary amines, 50 Prussian blue, 45 Prussic acid, Salts of, 66 Dissociation constant of, 150 Pseudonitroles, 48 Purpuric acid, see Murexid, 48 Pyrazol blue, 131 INDEX Pyridine, 132 Addition of methyl iodide to, 132 Behavior of, towards salt solu- tions, 1382 Reaction of, towards litmus, 132 Pyrocatechin, Action of ferric chloride on, 105 Quinoline, 132 Chlorplatinate of, 133 Dichromate of, 183 Hydrochloride of, 133 Skraup’s synthesis of, 132 Quinone, 113 monoxime, 103 Reactions of, 113 Reactions of alcohols, 18 Reagent bottles, 173 Labeling of, 174 Shelves for, 174 Rearrangement, Molecular, Beckmann’s, 112 Benzidine, 91 Diazoaminobenzene to ami- noazobenzene, 98 of maleic acid, 64 of stereoisomeric aldoximes, 110 Recrystallization, Process of, 19 Reflux-condenser, illustration of use of, 8 Resin formation with aldehydes, Resorcin green, 114 Resorcinol, Action of ferric chlo- ride on, 105 Coupling of, to form azo-dyes, 97 in the test for formaldehyde, 26 Rosaniline, Hydrochloride of, 33 in making Schiff’s reagent, Rosolic acid, Preparation of, 120 Rufigallic acid from gallic acid, 116 Saccharose, see cane-sugar, 76 Safranine dye, 103 189 Salicylic acid, Action of ferric chloride on, 116 Action of soda-lime on, 116 from oil of wintergreen, 116 Test for, in food, 116 Salts of weak bases, Hydrolysis of, 155 acids, Degree of hydroly- sis of, 155 Sandmeyer’s reaction, 96, 110 Schiff’s reagent for aldehydes, 33, 61 Schotten-Baumann’s reaction, 18, 59, 60, 105, 115 Schraube, 96 Separatory funnel, Use of, 16 Silver acetate, 39 nitrate, 15, 27, 37 Action on halogen alkyls, 15 Skraup’s quinolin synthesis, 132 Soap, 39 Soda-lime, 42 Sodium metallic, Action on alco- hols, 18 Disposal of residues, 24 use of, in drying ether, 24 Use of, in test for nitrogen, acetate, Action of water on, 39 Degree of hydrolysis of, 155 in the preparation of acetic acid, 38 Reactions with, 18, 38, 95, 96 acid sulphite, 34 benzene sulphonate, 89 carbonate in preparation of iodoform, 57 chloride, Effect of solutions on colloids, 148 formate, 37, 40 hydrogen sulphite, 34 hydroxide, Specific gravity of solutions of, 144 isonitromethane, 47 methyl sulphate, 67, 105 p-nitrophenyl-antidiazotate, 96 peroxide in making benzoyl peroxide, 115 press for making wire, 24 ® 190 Sodium salt of fluorescein, 120 formic acid, 37 eosin, 121 tetraborate, Degree of hydrol- ysis of, 155 Tannic acid as a mordant, 124 Tannin, 117 Tartaric acid, 72, 73 Calcium salt of, 73 Complex ions of, 73 Dissociation constant of, 152 Tartar emetic, 73, 124 Tautomerism, Cases of, 47, 61, 66, 73, 103 Tension of aqueous vapor, Table of, 142 Tertiary butyl alcohol, 21 Tetraethylammonium bromide, 51 Tetramethy]l- p2-diaminodiphen- ylmethane, 118 Thermometer readings, 137 scales, 1387 Thiazine dyes, 102 Thiocyanates, 67 Thioglycollic acid, Dissociation constant of, 151 Tin and hydrochloric acid as re- ducing agent, 92 Tollen’s reagent, 32 Preparation of, 32 Toluene, Action of concentrated sulphuric acid on, 88 as a solvent for anthracene, 127 o-Toluidine hydrochloride, De- gree of hydrolysis of, 155 p-Toluidine in the preparation of mauve, 103 hydrochloride, Degree of hy- drolysis of, 155 use of, in making parafuchsine, 120 Toluylene blue, 102 2,4,6-Tribromphenol, 104 Trichloracetic acid, Dissociation constant of, 151 INDEX Trichlorlactic acid, Dissociation constant of, 151 Triethylammonium bromide, 50 hydroxide, Dissociation con- stant of, 154 Triethylamine, 51 Trimethylammonium hydroxide, Dissociation constant of, 154 Trimethylsulphonium iodide, 44 Triphenylmethane, Derivatives of, 119 Tubes, Dissolving-, 162 Dropping-, 22 Ebullition-, 6 Twaddell’s hydrometer, 144 Readings of, 144 Ultramicroscope with colloids, Units, Heat, 140 Urea, Wéhler’s synthesis of, 69 Action of alkaline hypobro- mite on, 69 Action of nitric acid on, 69 Action of sodium hydroxide on, 69 Dissociation constant of, 154 hydrochloride, Degree of hy- drolysis of, 155 quantitative estimation of, 69 synthesis of, from phosgene, 69 Uric acid, Conversion into mur- exid, 70 Vacuum desiccator, Use of, 31 Valerianic acid, Dissociation con- stant of, 151 von Baeyer’s test for the ‘‘ double bond,” 12 Villiger, 34 Walden, 154 Walker, 154 Water, Dissociation constant of, 150 INDEX 191 Water, Action of calcium carbide Zinc dust as a reducing agent, on, 13 Test for, in alcohol, 8 chloride anhydrous as a con- Wohler’s synthesis of urea, 69 densing agent, 119 copper couple, 134 1-Xylose, Action of Fehling’s so- ° ethyl, preparation of, 134 lution on, 75 Reactions of, 134, 135 Gn a,