FIZE J O U R N A L OF I N D U S T R I A L A N D B N G I N E E R t N G C H E M I S T R P
320
few minutes a t IOO* C. in a water oven, cooled in a desiccator and weighed. CAFFEINE A N D T A N N I N
I n t h e method proposed by H. L. Smith’ for t h e determination of tannin in tea, directions are t h a t the caffeine be separated from the tannin by extraction from t h e aqueous solution with chloroform. T h e method2 directs t h a t 50 cc. of t h e solution be shaken out with four 30 cc. portions of chloroform, making a total of 1 2 0 cc. This method was tested from t h e viewpoint of t h e distribution ratio, using 1 0 5 cc. of water and 3 0 cc. of chloroform. The results are given below: Wt. caffeine Wt. found in 20 used cc. of chlor. layer 0.0653 0,0375 0.0698 0.1228 0.2061 0.1180
Wt. in chlor. layer 0.0563 0.1048 0.1770
Wt. in water layer 0,0090 0.0180 0.0291
CI
a
0.0456 0.0492 0.0470
Average, 0.0473
Hence, on one shaking with 30 cc. of chloroform, b u t ‘/14 of the caffeine remains in t h e water layer. On four washings with 30 cc. of chloroform for each extraction, there is only 1 / 3 5 , 8 ~ ~of the original amount left. This is, of course, beyond our limits of accuracy and such washing is unnecessary. Four washings, using I O cc. for each extraction, are far more satisfactory and economical. Under such conditions, 99.7 per cent of t h e caffeine is extracted, using a total of 40 cc. of chloroform. If t h e aqueous solution is shaken out five times with I O cc. portions of chloroform, 99.95 per cent is extracted. It might be pointed out thaf the aqueous liquid does not need t o be made either acid or alkaline t o get a good separation with chloroform. The validity of t h e above is shown by t h e following analysis. Known weights of caffeine were shaken out from distilled water solutions with four I O cc. portions of chloroform, t h e chloroform evaporated over night, t h e residue dried in a desiccator and weighed. Wt. caffeine started with 0.0809 0.1545
Wt. total residue 0.0816 0.1547
Residue in chloroform 0.0012 0.0012
Wt. caffeine Percentage obtained of total
0.0804 0.1535
99.4 99.3
This was repeated b y another analyst with another sample of chloroform with these results: 0.2000 0.2000
0.2005 0.2002
0.0012 0.1993 0.0012 0.1990 Calculated amount,
99.6 99.5 99.7
T h e distribution ratio of tannin between water and chloroform was also run. The chloroform solution, however, did not leave a weighable residue. Hence, error from this source need not be feared in this determination. SUMMARY
I-A practical application of t h e distribution ratio has been made in a study of a few of the extraction methods given in t h e bulletins of t h e United States H. L. Smith, Analyst, 38, 312; Chapman, Chem. Abs., 2, 1477; 4, 1081. 2 This method is not given in the bulletins of the United States Bureau of Chemistry but it is included in this paper as an example of somewhat excessive washing for the extraction of caffeine. 1
Vol. 6 , No. 4
Bureau of Chemistry with t h e view of pointing out t h e fact t h a t definite directions are needed in our extraction methods which give a definite amount of t h e material in question. 11-A modification of the method of analysis for acetanilid in hydrogen peroxide has been suggested. 111-The method for acetanilid, vanillin and coumarin in vanilla extracts has been discussed from t h e point of view of t h e distribution ratio. IV-The methods now in use for salicylic acid, benzoic acid and &naphthol have been studied and found satisfactory from this point of view. V-A method has been suggested for the analysis of saccharin b y extracting with amyl acetate and a modification of t h e present method with sulfuric ether proposed which gives definite results. VI-It has been shown in t h e analysis of caffeine (in t h e particular case referred to) t h a t the amount of chloroform used for t h e extraction was excessive. VII-The fact has been emphasized t h a t a larger number of extractions, using a smaller volume of solvent for each washing, is better t h a n a fewer number of extractions using a larger amount. A much more extended study of t h e methods of extraction is being carried on in this laboratory a t t h e present time. SOUTHDAZOTAFOODAND DRUGDEPARTMENT VERMILION
SOME REACTIONS OF CHRYSOPHANIC ACID WITH REFERENCE TO ITS DETECTION IN COMPLEX MEDICINAL. PREPARATIONS B y E. MONROEBAILBY Received December 1, 1913
Chrysophanic acid, dioxymethylanthraquinone, CIS-
H1004, is a yellow color principle of weakly acid character occurring in a number of medicinal plants, notably in senna and rhubarb, and may be obtained also from its anthranol’ chrysarobin, C16H1203, which is present in Araroba or Goa powder.2 T h e presence of t h e free acid in plants is presumably due t o t h e enzymic hydrolysis of t h e glucoside, chrysophan. Chrysophanic acid is not the active principle of rhubarb, nor does the cathartic action of senna appear t o be due, primarily, t o its presence. It is soluble in alkalis with t h e production of a deep cherry-red color. If the alkaline solution is heated with a little zinc dust reduction takes place and t h e red color changes t o yellow, t h e anthranol being f ~ r m e d . ~ Reoxidation in t h e alkaline solution takes place very readily; exposure to t h e air or simple dilution with water affects it and a drop or two of hydrogen dioxide produces t h e change almost immediately. It behaves as an indicator, although its merits as such do not appear t o have been investigated. Toward reactions of oxidation chrysophanic acid appears t o be quite stable. When taken into the body it may be, apparently, eliminated unchanged in t h e urine. It is said t h a t after the ingestion of senna t h e urine becomes intensely yellow and if rendered Liebermann, Be*. d . chem. Ges., 1888. Oesterle, Arch. Pharm., 243 (1905). 434. a Allen’s “Commer. Organ. Anal.,” 4th ed., Vol. V, p. 208; cf. “Alizarin.”
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1
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Apr.9 1914
T H E J O U R N A L 5 F I N D U S T R I A L A N D E N G I N E E R I N G CH E M I S T R Y
alkaline by sodium hydroxide a deep red color is produced. Of nine men in t h i s laboratory, however, who took prescribed doses of senna-in preparations compounded with syrup of figs-in only two cases were positive tests given on examination of t h e urine twelve hours later.' The applicability of chrysophanic acid for purposes of artificial coloring are apparent, one instance having been cited recently by Thum.* The sophistication of powdered rhubarb with powdered turmeric has been practiced and Howie3 and others have given some a t tention to the detection of curcumin in such cases. I n t h e inspection of patented and other medicinal preparations, the detection of chrysophanic acid serves t o indicate t h e presence of a restricted group of vegetable constituents. And, finally, t h e similarity of many of its reactions t o those of phenolphthalein, a substance of not uncommon okcurrence in medicines, makes its detection in presence of t h a t substance desirable. If a n alcoholic extract containing chrysophanic acid is dealcoholized or sufficiently diluted with water, acidified with a few drops of concentrated hydrochloric acid and shaken out with ether,4 the coloring matter is taken up b y t h e solvent and t h e ethereal layer is colored yellow. On washing the solvent with dilute alkali ( ~ 1 , ' ~per cent ammonium hydroxide was used) t h e color is transferred t o the aqueous solution which is colored red. Similarly treated, picric acid and t h e color principle of hydrastis yield no red color t o dilute alkali nor does their presence interfere with subsequent tests; but curcumin, haematoxylin, and phenolphthalein yield colors not to be distinguished in certain concentrations from t h a t produced by chrysophanic acid. I n the cases of curcumin and haematoxylin, however, the color of their alkaline solutions is slowly fugitive. After standing over night a t 40°1500 the red element is entirely lost, b u t the red color of chrysophanic acid and phenolphthalein is persistent.
I
If this solution is now acidified and shaken out with ether, the interfering color principles, curcumin and haematoxylin, are eliminated. Their absence can be demonstrated by concentrating a portion of the ether shake-out on filter strips and testing as follows: ( I ) Moisten one of the strips with a drop of strong hydrochloric acid. K O pink color will be obtained, showing the absence of haematoxylin. (2) Moisten another strip with a mixture of hydrochloric-boric acids. N o red color will be produced, showing the absence of curcumin. (3) Moisten a third strip with dilute ammonium hydroxide. A pinkish red color will indicate t h e presence of chrysophanic acid or phenolphthalein or both. To eliminate phenolphthalein transfer a portion of the ether shake-out obtained above t o a test tube and drive off the ether. Add a little zinc dust and 4-5 cc. of 2 5 per cent sodium hydroxide, boil until the red color is discharged and cool the solution. By this treatment chrysophanic acid is reduced, as already described, the solution becoming yellowish, and phenolphthalein is reduced t o phthalin which is colorless. Dilute the alkaline solution with water or treat it with a few drops of hydrogen dioxide and t h e characteristic cherry-red color of chrysophanic acid will be obtained. Phthalin remains unoxidized under these conditions. Curcumin and haematoxylin both undergo reduction by means of zinc dust and sodium hydroxide and neither are subsequently oxidized by hydrogen dioxide, but their yellow or brown solutions mask the color of chrysophanic acid in certain proportions and thus ,make t h e test for t h e latter less distinct. I t is therefore best t o eliminate these substances by the method described. ANALYTICAL LABORATORY AGRICULTURAL EXPERIMENT STATION CONNECTICUT NEW HAVEN
LABORATORY AND PLANT
IMPROVEMENTS IN THE IODINE PENTOXIDE METHOD FOR!THEiDETERMINATION OF CARBON MONOXIDE IN AIR By ATHBRTON SBIDBLL Received January 10, 1914
The iodine pentoxide method is based upon t h e reaction 120s g C 0 = ;COS Iz which has been found to be quantitative a t approximately I 5 0 ' . The sample of air is passed first through absorption tubes containing potassium hydroxide and concentrated sulfuric acid and then through a U-tube containing powdered iodine pentoxide, and immersed in an oil bath heated t o 150'. It is obvious t h a t either the resulting iodine or the carbon dioxide may be used as the measure of the carbon monoxide.
+
+
1 These tests were made with commercial laxative preparations in which senna was declared to be an ingredient. The amounts of senna in many cases may have been too small to give the physiological test. 2 A m . J . Pharm.. 85, 1 , 19. 8 Pharm. Jour., Nov., 1873; also Am. J. Pharm.. 4 (1874): 1, 16. 4 The emulsion which forms is readily destroyed by adding acetone.
I
The apparatus as usually described' consists of a series of U tubes, spiral or other absorption tubes and potash bulbs connected with a suitable aspirator. On assembling a n apparatus according to the usual descriptions, i t became evident t h a t a reduction of the dead air space would materially shorten the time required for a determination and reduce the correction factor resulting from t h e slight decomposition of t h e iodine pentoxide reagent by the air used t o drive the sample through the apparatus.: I t was also hoped t h a t t h e rate a t which the sample is drawn through the apparatus could be increased. The improved apparatus which has been developed is shown in t h e accompanying diagram. The essential feature of i t is the special form of absorption 1
Nicloux, Compt. rend., 126 (1898), 746; Kinnicutt and Sanford,
J. Am. Chem. Soc., 22 (1900), 14; Levy and Pecoul, Compl. rend., 140 (1905), 98; 142 (1906), 162; Morgan and McWhorter, J. A m . Chem. Soc., 29 (1907), 1589; Weiskopf, J . Ckem. M e t . SOL.S. Africa, 9 (1909): 258, 306; and also Chem. News, 100 (1900). 191; Goutal, Ann. chim. a n d 16 (1910), 1-7; Levy, J . SOL.Ckem. I n d . , S O (1911), 1437.
aPPl.,
