Chemical examination of jalap / by Frederick B. Power and Harold Rogerson.

  • Frederick Belding Power
Date:
[1910]
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Chemical examination of jalap / by Frederick B. Power and Harold Rogerson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    22/38 (page 98)
    I These results would indicate that the above-described product con- sisted chiefly of a higher homologue of convolvulinolic acid, having the formula C17H3403. As previously noted, a similar product was obtained by the acid hydrolysis of the chloroform extract. “ Ether Extract.—This was a soft, black, resinous mass, and amounted to 8 grams. It was examined, but nothing of a definite character could be obtained from it. V. Alcohol Extract of the Resin. This extract, as indicated in the first part of this paper, was the chief constituent of the original crude resin. When quite dry it could readily be reduced to a light brown powder, and on treating it in dilute alcoholic solution with successive portions of animal charcoal, a nearly white product was obtained. The latter, after drying at no°, melted at 150- 1600, and, when heated on platinum foil, it burned with a smoky flame, leaving no residue. The optical rotatory power of the purified alcohol extract was deter- mined, with the following result: A solution containing 0.9905 gram of dry substance in 25 cc. of absolute alcohol had aD —1.470 in a 1 dcm. tube, whence [a]h —37.1°. This value is almost precisely the same as that obtained for the purified total resin, namely [a]D —37.o°, as recorded in the first part of the paper. It also agrees closely with the rotation ([a]D —36.9°) observed by Kromer1 for the product designated as “convolvulin,” the latter consisting of that portion of jalap resin which is insoluble in ether. Fusion with Potassium Hydroxide. Twenty grams of the alcohol extract of the resin were fused with 120 grams of potassium hydroxide in a nickel basin, the temperature of the mixture being kept at about 150° for some time, after which it was slowly increased to 260°, with constant stirring. When the reaction had ceased, and the mass had become pasty, it was allowed to cool, and then dissolved in water. The solution was acidified with sulphuric acid, and distilled with steam until volatile products ceased to pass over. The distillate, which was found to contain only acidic substances, was made alkaline with sodium carbonate, the liquid concentrated, acidified, and extracted with ether, when a quantity of an oily acid was obtained. This was distilled twice under the ordinary pressure, and the following fractions finally collected: (1) Below 165°; (2) 165—1750; (3) 175-185°; (4) 185-245°; (5) 245-280°. Fractions (1), (2) and (3) were analyzed. It would appear from these results that fraction (1) consisted of a nearly pure butyric acid, while fractions (2) and (3) evidently contained valeric acid. The subsequent fractions consisted of mixtures of acids of higher molecular weight. 1 J. Chern. Soc. Abst., 66, i, 540 (1894).