V- A. (r<xn^-. 
 
 Si~udte$ 0-f- The, LrocsoB / ne, Jzx~t~r'oic,-f~' Of- 
 
 pi^iTczl r& Leave# . 
 
 \ 
 
 Iii 
 
 ■ M. 
 
 
STUDIES OF THE GASOLINE EXTRACT 
 
 OF 
 
 DIGITALIS LEAVES 
 
 BY 
 
 VIRGIL A. GANT 
 
 THESIS 
 
 FOR THE 
 
 DEGREE OF BACHELOR OF SCIENCE 
 
 IN 
 
 
 
 COLLEGE OF LIBERAL ARTS AND SCIENCEwS 
 
 UNIVERSITY OF ILLINOIS 
 
 1921 
 
Digitized by the Internet Archive 
 in 2015 
 
 https://archive.org/details/studiesofgasolinOOgant 
 
UNIVERSITY OF ILLINOIS 
 
 \$%\ 
 
 1 
 
 Hjl I 9 2_A_ 
 
 THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY 
 
 -YJDiGLIL-JL* GAHT. 
 
 ENTITLED..SXIIDI]i:a-QZ-l^-[>ASiILnrK^TRACX-iIg-JDiaiXAUIS--LEAV£a 
 
 IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE 
 degree of __ Baj3he_lP_r__of 
 
 Instructor in Charge 
 
 Approved 
 
 
 HEAD OF DEPARTMENT OF 
 
 /OO 
 
 *3u : t ci C C>0 
 

 I 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TABLE OP CONTENTS 
 
 introduction 
 
 Page 
 
 Discussion of the Problem 1 
 
 Historical 2 
 
 Properties and Nature of Pats and Waxes 3 
 
 Part X. Analysis of the Gasoline Extract of 
 
 Digitalis Leaves 5 
 
 Part II. Analysis of gasoline-free and chlorophyl- 
 
 free fatty acids 9 
 
 Conclusions 12 
 
 Bibliography 17 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Acknowledgment 
 
 To Dr. George D. Beal, who, by his kind, careful, and 
 willing supervision, has caused me to go into this work 
 with a heart-felt and whole-hearted purpose, I wish to 
 extend my most sincere feeling of gratitude. 
 

 
 
 
 
 ' 
 
 c - * 
 
 ♦ 
 
 ' 
 
 
 r 
 
 ♦ 
 
INTRODUCTION 
 
 Discussion 
 
 One of the greatest problems in the manufacture of chemical 
 and phama cent i cal products to-day is the utilization or disposal 
 of by-products* Sometimes the by-products are such that they are 
 harmful to life in the region around the plants, and must be dis- 
 posed of as quickly as possible* More often, however, the by- 
 products give promise of being of some use to man, and it then be- 
 comes the duty of the chemist to find a use for this product which 
 might otherwise be thrown away and lost* 
 
 In the manufacture of the heart-tonic, Digitol, there is a 
 certain amount of vegetable fat in the compound, which, if not re- 
 moved will become rancid or n strong" and thus lessen the pharmaceu- 
 tical value and keeping qualities of the tonic* This rancidity is 
 thought to be due to certain unsaturated fatty acids which have 
 foul odor when oxidized* Hence, in order to avoid this undesirable 
 quality the leaves of the digitalis plant are first extracted with 
 gasoline in order to completely dissolve the vegetable fats* Gaso- 
 line is used because it dissolves the fats and leaves behind the 
 valuable proximate principles* This gasoline extract, also, con- 
 tains much chlerophyl from the leaves. It is important that the 
 chlorophyl be removed from the tonic because it must be clarified 
 in order to be attractive* 
 
 The problem has been to determine the nature of the gasoline 
 extract and, if possible, the character of the various extractive^ 
 It has included the study of the extract perse, with the determina- 
 tion of the unsoponifiable matter, largely gasoline residues; the 
 

 
 
 
 - 
 
 . 
 
 
 
 r 
 
 
- 2 - 
 
 character of the gasoline free extract, and a study of the chlere- 
 phyl-free fatty matter. The methods of analysis followed have been 
 largely those of the Association of Official Agricultural Chemists, 
 with frequent reference to Lewkowttsch, Technology of Oils, Fats 
 and Waxes on questions dealing with the interpretation of results 
 and special separations. 
 
 Historical 
 
 Digitalis Foluim of the gardens, grown as an ornamental flow- 
 ering plant is the common Foxglove. The variety most commonly used 
 medicinally is Digitalis purpurea Linne ( Fam. Scrophulariaceae ) • 
 
 The dried leaves of the plant constitute the official part and are 
 used without the presence or admixture of more than 2 percent, of 
 stems, flowers or other foreign matter. The leaves when entire at- 
 tain a length of 30 cm. and a breadth of 15 cm. , ovate to oval a- 
 bruptly contracted into winged petioles, the latter from 5 to 10cm. 
 in length, or in the smaller leaves, nearly absent; margin crenate, 
 irregular (the commercial article usually more or less crumpled and 
 broken), thin, dull, pale green or gray and densely pubescent on the 
 lower surfaces; upper surfaces wrinkled and sparsely hairy; the 
 midribs flat and the principal veins broad and purple; odor slight; 
 taste strongly bitter. 1 The leaves are carefully plucked and clean- 
 ed so as not to have dirt clinging to them. The lower leaves of the 
 plant, especially when grown on a loose loamy soil, will have the 
 highest ash content, due to earthy material, and even the upper 
 leaves will have a higher ash content if gathered soon after a 
 splashing rain. After drying, they are pulverized, giving a dark 
 green powder. From this powder, the various preparations such as 
 

 
 
 
 
 
 r 
 
 
 
 
-3- 
 
 Fluidextractum Digitalis, Infusum Digitalis, and Tincture Digitalis 
 are made* 1 ' 
 
 Properties and nature of Fats and Waxes, 
 
 Fats and waxes are both esters of the aliphatic mono carboxylic 
 acids of even carbon content, lmown as the fatty acids. Fats are 
 esters of the triatamic alcohol glyceral while waxes are esters of 
 monatomic alcohols. As a rule the alcohols of the waxes are of the 
 same number of carbon atoms as the acids with which they have been 
 associated, and probably have their source in the same aldehjzde. 
 
 In order to determine the various properties and nature of fats 
 and waxes, the saponification and iodine numbers are used as con- 
 stants. 
 
 The saponification or (XoStsoTffer ) number is the number of 
 milligrams potassium hydroxide used in saponifying one gram of the 
 sample. From 1 to 3 grams of the sample are saponified by reflux- 
 ing on the water bath, with alcoholic KOH until the oil is complete- 
 ly saponified. The excess alkali is titrated with standard hydro- 
 chloric acid and the number of milligrams of potassium hydroxide is 
 calculated by taking the difference between the amount of acid need- 
 ed to titrate the blank and the amount needed to titrate the sample. 
 The saponification number is in a sense a measure of the mean mole- 
 cular weight of the mixed fatty acids. The iodine number is the per- 
 centage of iodine absorbed by the fat. The official methods used is 
 that of Hanus where a solution of iodine monobromide in glacial acet- 
 ic acid is used. This solution is used because it is more stable 
 than the others and reacts more quickly with the fat. The theory of 
 this constant is based on the fact that where we have an ethylene 
 

 
 
 
 
 
 
 
 
 - 
 
 
 
 
 T 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 u > ' 
 
 
 
 
 
 
 . 
 
 - 
 
 . 
 
 V 
 
 
 
 
 t 
 
 
 
 
 
 •* 
 
 
 
 
 
 
- 4 - 
 
 linkage, the earhon atoms will add between them a mole of iodine or 
 a halide of iodine, becoming saturated* i’his holds true in the case 
 of I Br dr ICl also since one atom of iodine and one atom of bro- 
 mine or chlorine will add in the same manner as two atoms of iodine* 
 In the calculation, we assume that the addition is all iodine* 
 
 ‘i’he method consists essentially in dissolving the fat in chlor- 
 oform and allowing the solution to react with a measured volume of 
 the iodine solution in a glass-stoppered Erlenmeyer flash for a def- 
 inite length of time, adding potassium iodide solution, and titrat- 
 ing the excess iodine with standard sodium thiosolfate using starch 
 as an indicator* A blank is run in the same manner* jjYom the dif- 
 ference between the blank and the sample, the percentage of iodine 
 is calculated* ‘i’his constant give an exact measure of the unsatura- 
 ted acids present; or rather of the degree of unsaturation, the high 
 er the iodine number, the higher the per cent, of unsaturated acids* 
 
5 
 
 Part I 
 
 Analysis of the Gasoline Extract of Digitalis Leaves, 
 
 4 . 
 
 Saponification Dumber 
 
 The saponification number was determined in the usual manner 
 by refluxing from one to three grams, accurately weighed, with 25cc. 
 of § alcoholic potassium hydroxide. The excess of potassium hydrox- 
 ide was determined by titration with D/2 hydrochloric acid, using 
 phenol phtholein as an indicator, A blank determination carried out 
 with another 25co. portion of the alcoholic potash gave the acid e- 
 quivalent of the total alkali used. Owing to the presence of so 
 much chlorophyl in the extract, it was very difficult to arrive at a 
 sharp end point in the titration. Only by observing the color of 
 the solution in very thin layers could any decision be made as to the 
 completeness of the titration. 
 
 Results: 
 
 Wt. of sample no, 1 — 1.8663 gms. 
 
 " " n 2 - 1.8660 gms. 
 
 " " " " 3 1*8608 gms. 
 
 C.C. HC1 req. for Do. 1 — 5.2 
 
 " " " " 2 5.2 
 
 " ” " " 3 5.15 
 
 saponification value for no. 1 90.8 
 
 " " " " 2 90.7 
 
 n " ” " 3 90.2 
 
 Av.= §0.5 
 
 25e.c. alcoholic EOH s 28.5c. c. HC1 D.F .5106 
 This is an exceedingly low saponification value and shows that the 
 extract consists chiefly of the organic solvent and chlorophyl with 
 
 comparatively little fat 
 

 
 
 
 
 
 
 
 
 
Unsaponifiable Matter. 4 
 
 In this determination, the extract was saponified with alcohol- 
 ic potash, dealcoholized, and the soap dissolved in water* The soap 
 solution was extracted three times with ether to remove the unsapon- 
 ifiable matter, but since chlorophyl may be extracted from a soap 
 solution by means of ether, the unsaponifiable matter had a green 
 color* The residue was dried very quickly and weighed* The odor of 
 hydrocarbon oils was easily detected. 
 
 Ke suits : 
 
 wt. of sample no. 1 3.5304 gms. 
 
 " " " no. 2 3.5824 gms. 
 
 " " residue no. 1 0.1490 gms. 
 
 " " " no. 2 0.1488 gms. 
 
 per cent, unsaponifiable matter in no. 1 4.22 
 
 " " " " "no. 2 — 4.15 
 
 Av. 4.18$ 
 
 The values thus obtained do not represent the total unsaponifi- 
 able matter actually present, but only that which survived the heat 
 treatments during saponification, extraction and drying, naturally 
 a large part of the unsaponifiable matter of the original extract 
 consisted of gasoline residues, much of which would be lost during 
 these operations. 
 
7 
 
 Iodine Number 
 
 This was determined by the method of Hangs usuing a solution of 
 iodine monobromide in glacial acetic acid. The determination was 
 carried out in the usual manner, care being taken not to allow the 
 samples oir blanks to stand any longer than necessary because it was 
 found that the iodine number was lowered appreciably upon standing. 
 This is due to the absorption of oxygen by the unsaturated fatty 
 acids. 
 
 sample 
 
 .Blank 
 
 Na 2 Sg0 3 
 
 c * c . 
 
 - used 
 
 Excess 
 
 Iodine no 
 
 .2590 
 
 87.5 
 
 74.6 
 
 12.9 
 
 79.01 
 
 .2590 
 
 87.5 
 
 74.6 
 
 12.9 
 
 79.01 
 
 .2590 
 
 87.5 
 
 74.6 
 
 12.9 
 
 79.01 
 
 .1250 s N.F. of HagSgOg 
 
 Soluble Acids,^ 
 
 Prom 1 to 5 grams of the sample were saponfied, the soap solu- 
 tion dealcoholized, and made slightly acid with a measured excess of 
 standard hydrochloric acid. The fatty acids were liberated by boil- 
 ing gently to form a layer of oil on top. The flask was cooled, the 
 acid solution poured off, the soluble acids dissolved by washing the 
 oily layer with hot water and the the solution titrated with N/10 
 alkali using phenothalein as an indicator. 
 
 
 Sample 
 
 c.c.Na OH 
 
 wt. of 
 
 per cent. 
 
 
 
 used 
 
 Butyric acid 
 
 soluble acids 
 
 1 . 
 
 4.5191 
 
 4.12 
 
 .0362 
 
 .802 
 
 2. 
 
 4.5191 
 
 4.12 
 
 .0362 
 
 .802 
 
 3. 
 
 4.5191 
 
 4.12 
 
 .0362 
 
 .802 
 
 
 
 .1314 = H. P. 
 
 Na OH 
 
 
8 
 
 4 
 
 Insoluble Acids {Hehner Number). 
 
 The flask containing the cake of insoluble acids was allowed to 
 drain and dry for 18 hours, and the acids then dissolved in hot ab- 
 solute alcohol into a tarred dish after which the alcohol was evap- 
 orated and the dish and contents dried to constant weight. The per 
 cent, of insoluble acids was calculated from the weight of the sam- 
 ple used in determining the soluble acids. 
 
 Sample no. 1 s 4.5191 g. 
 
 " no. 2 = 4.5191 g. 
 
 " no. 3 = 4.5191 g. 
 
 per cent. 
 
 1 W 1U &?8t Ci<iS 
 
 (2) 35.86 
 
 (3) 35.86 
 
 wt. of residue from no. 1 
 " " n no. 8 
 
 " " " " no. 3 
 
 1.6205 
 
 1.6206 
 1.6205 
 
 Solid and Liquid IPatty Acids. 
 
 4 
 
 About 10 grams of the sample were saponified in the usual man- 
 ner and after neutralizing the excess alkali, the lead soaps were 
 precipitated with lead acetate solution, and treated with ether. The 
 soluble lead soaps supposed to represent the unsaturated acids were 
 filtered off and decomposed with -e th e r hydrochloric acid, forming 
 Lead chloride which was drawn off and the ether solution evaporated 
 Ln an inert atmosphere to determine the per cent, of liquid acids. 
 
 The insoluble lead soap left on the filter and in the flask 
 vas washed into the flask, decomposed with hot hydrochloric acid, 
 cashed with hot water, cooled, dissolved in hot 95$ alcohol, evap- 
 orated, dried and weighed as solid fatty acids. Only ten grams were 
 used owing to the small amount of fat in the extract. 
 
 

 1 
 
 / 
 
 / 
 
 
 
 
 
 
 
 
 c 
 
 
 
 
 
 
 
 
9 
 
 wt. of solid per cent 
 acids solid acids 
 .0839 1.85 
 
 .0839 1.85 
 
 wt. of liquid 
 
 per eent 
 liquid acid 
 
 1. 9.0382 
 
 2. 9.0382 
 
 Sample 
 
 acids 
 
 .3575 
 
 .3577 
 
 7.91 
 
 7.91 
 
 Iodine number of Liquid ratty Acids 
 
 1. .3575 
 
 2. .3577 
 
 Sample 
 
 c.c. used 
 
 25.1 
 
 25.1 
 
 Iodine no 
 106.09 
 106.09 
 
 B. I 5 , of Ba 2 S 2 0 3 -.11905 
 
 Part II 
 
 Analysis of gasoline-free and chlorophyl-free Pat 
 
 In order to attack this part of the work, 50 grams of the ex- 
 tract were saponified with alcoholic potassium hydroxide, and the 
 alcohol boiled off completely while frequently adding small amounts 
 of water to replace the alcohol. The soap was diluted with water, 
 acidified with sulfuric acid, and boiled gently to set free the fat- 
 ty acids from their potassium salts. A thick black layer formed on 
 top. This layer consisted of the fatty acids and chlorophyl. Since 
 it was a hard cake, a hole was punched thru it and the acid solution 
 poured off. The cake of acids and chlorophyl was then dissolved in 
 an aqueous solution of sodium hydroxide to form the sodium salts of 
 the fatty acids. Since these salts are insoluble in ether, or only 
 slightly soluble, and since chlorophyl is soluble in ether, the al- 
 kaline solution was poured into a separatory funnel and repeatedly 
 extracted with ether. The soap solution, free from chlorophyl had 
 a light brown color. This solution was boiled gently with dilute 
 sulfuric acid until a clear brown layer of fatty acids formed on top. 
 The remainder of this work was done on the fats obtained in this man- 
 ner. Very small amounts were used and the work done very carefully 
 

 
 
 
 
 
 O 
 
 1 
 
 i 
 
 r * 
 
 - 
 
10 
 
 because only three grams of fat were obtained from 50 grams extract. 
 The fat was not absolutely free from gasoline. 
 
 Iodine Number of Purified Patty Acids. 
 
 Carried out in the usual manner as already described. 
 
 Sample Blank Excess c.c. used Iodine no. 
 
 Na^SpOa 
 
 1. .8713 94.95 31.70 63„25 114.2 
 
 1. .8713 94.95 31.70 63.25 114. E 
 
 N.F. Na 2 S 2 0 3 « .1239 
 
 Saponification Equivalent of Purified Patty Acids. 
 
 Carried out in the usual manner as already described. 
 
 c.c.HCl c.c.HCl c.c.HCl Saponification 
 
 for blank for excess used by sample Equivalent 
 70.3 66.5 3.8 146.9 
 
 70.3 66.5 3.8 146.9 
 
 N.F. of HC1 I .5106 
 
 Unsaponifiable Matter. 
 
 The solution remaining from the determination of the saponifi- 
 cation equivalent was again made alkaline and extracted repeatedly 
 with ether. The ether was evaporated and the residue resaponified 
 with alkali. This soap solution was then extracted with ether to 
 determine the true unsaponifiable matter. 
 
 Sample wt. of residue per cent 
 
 unsaponifiable Matter. 
 
 1. 1.0398 .1786 17.18 
 
 2. 1.0397 .1785 17.18 
 
 These results express the per cent, of unsaponifiable matter 
 including hydrocarbon residues from the gasoline. To remove the 
 hydrocarbon oils from the total unsaponifiable matter, the residue 
 was boiled with 95$ alcohol, cooled, filtered, and the filtrate e- 
 vaporated, dried and weighed. 
 
 Sample 
 1. 1.0398 
 2 1.0397 
 

 
 
 
 
 
 
 
 
 
 
 
 
11 
 
 Sample wt. of residue per cent of 
 
 unsap. matter in pure 
 fatty acids. 
 
 1. 1.0389 .0159 1.53 
 
 2. 1.0397 .0156 1.53 
 
 These results express the per cent, of unsaponif iable matter of 
 the phytostdrol type in the pure fatty acids containing no hydrocar- 
 bon oils or chlorophyl. 
 
 Calculation of Mean Molecular Weight of Purified 
 Mixed Patty Acids 
 
 The neutralization value of the purified mixed fatty acids is 
 not expressed by the saponification equivalent of 146.9 because the 
 fatty acids used in determining the saponification equivalent con- 
 tained 17.18$ unsaponif iable matter. The actual weight of fatty acid 
 ;itrated is 0.8610 gm t and the weight of potassium hydroxide consumed 
 per gram of acid is 0.1264 gm. 
 
 Formula : 
 
 M- mol. wt. expressed in grams, (theory requires that M 
 grams be neutralized by 56.1 grams potassium hydroxide) 
 
 Ifs no. grams of potassium hydroxide required to neutralize 
 1 gram of pure fatty acids. Then we have the proportion 
 M:56.1::l:n; hence Ms 56.1 1 
 
 0.1264 Ms 444.2 
 

IE 
 
 Melting Point of Pure Patty Acids 
 
 Ho melting point was taken because the free fatty acids were 
 liquid after standing 48 hours at room temperature. 
 
 Conclusions. 
 
 Since only 3 grams of fatty acids were obtained from 50 grams of 
 the gasoline extract, it is evident that the extract contains a very 
 small amount of fatty acids. The bulk is made up of gasoline and 
 chlorophyl. The solution may be freed from the organic solvent by 
 evaporation on the water -bath under diminished pressure. To obtain 
 the free fatty acids, it is necessary to saponify the extract with 
 alcoholic potassium hydroxide, and boil with dilute sulfuric acid un- 
 til the oily layer floats on top. This oily layer consisting of fat- 
 ty acids and chlorophyl is then treated with an aqueous solution of 
 sodium hydroxide and repeatedly extracted with ether to remove the 
 chlorophyl. After all the chlorophyl has been removed, the free fat- 
 ty acids may be liberated by again adding dilute sulfuric acid and 
 boiling until the oily layer appears. The free fatty acids may then 
 De extracted with ether, the ether evaporated, and the fatty acids 
 iried. 
 
 The small amount of free fatty acids in the extract is accounted 
 for by the fact that most vegetable fats and oils are found in the 
 seeds and kernels, and not in the leaves. 
 
 The iodine value of the mixed fatty acids is 114.2 and that of 
 the liquid fatty acids is 106.09. The liquid fatty acids are supposed 
 to represent the unsaturated acids. Therefore, most of the mixed fat- 
 ty acids are unsaturated. An iodine number of 114. E is too low to en- 
 able the oil to be classed as a drying oil. This value classes the 
 nixed fatty acids as a semi-drying oil. The mixed fatty acids when 
 

13 
 
 left exposed to the atmosphere for 48 hours formed a very thifl scum 
 or membrane. This is characteristic of a semi -drying oil. 
 
 After removing the unsaponifiable matter from the mixed fatty 
 acids and calculating the true neutralization value the mean molecu- 
 lar weight was found to be 444. E. These values correspond very close- 
 ly to a mixture of erucic acid with a mean molecular weight of 338 
 and a neutralization value of 166 with some polymerized products 
 formed during the extractions. This classes the fatty acids with the 
 solid waxes which have acidswith molecular weights of over 300. The 
 presence of hydrocarbon residues from gasoline perhaps prevented the 
 fatty acids from solidifying. Although, these hydrocarbon residues 
 were present, the mixed fatty acids in their free state became viscid, 
 thus showing a tendency at least to become solid. 
 

 
 
 
 
 * 
 
 
 “ ' 
 
 
 
 . . 
 
 
 
 
 
 
 
 
 
 
 - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 . 
 
 
 
 
 
 
 
 
 
17 
 
 BIBLIOGRAPHY 
 
 1* United States Pharmacopoeia. 
 
 (9th decennial Revision) 
 
 2. Lewkowitsch, Technology of Oils, 
 
 Pats, and Waxes. 
 
 3. Sherman, Organic Analysis. 
 
 4. Methods of Analysis, Association 
 
 of Official Agricultural Chemists.