Chemical examination of pumpkin seed / by Frederick B. Power and Arthur H. Salway.

  • Power, Frederick B. (Frederick Belding), 1853-1927.
Date:
[1910]
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Chemical examination of pumpkin seed / by Frederick B. Power and Arthur H. Salway. 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.

    11/18 (page 353)
    The filtrate from the basic lead acetate precipitate was treated with hydrogen sulphide for the removal of the excess of lead, filtered, and this filtrate concentrated under diminished pressure. A reddish brown sirupy liquid was thus obtained, which contained a large amount of sugar, since it readily yielded d-phenylglucosazone, melting at 2150. The liquid deposited nothing crystalline, even on long standing, and a portion, when dried in purified sawdust and extracted successively with ether, ethyl acetate, and alcohol, likewise yielded nothing of a crystal- line nature. Treatment oj the Purified Aqueous Liquid with Dilute Sulphuric Acid. A portion of the aqueous liquid which had been purified by treatment with basic lead acetate, as above described, was heated for some time in a reflux apparatus with such an amount of sulphuric acid that the latter represented about 5 per cent, by weight of the mixture. On sub- sequently passing steam through the liquid, the distillate was found to contain formic and acetic acids, but no oily drops. The aqueous, acid liquid remaining in the distillation flask contained a comparatively large quantity of resin. This was collected and well washed with water, but it was quite insoluble in the usual organic solvents, and possessed no further interest. After the separation of the resin, the aqueous liquid, which had a dark brown color, was extracted many times with ether. The combined ethereal liquids were washed, dried, and the solvent re- moved, when about 3 grams of a yellowish brown oil were obtained, which was fractionally distilled under the ordinary pressure. A small fraction was collected at 100-120°, which contained formic and acetic acids, but the larger portion distilled between 230 and 240°. On redis- tilling the latter, it passed over between 240 and 260°. This oil possessed a light yellow color, was freely soluble in water, and gave a precipitate with phenylhydrazine acetate. It was, furthermore, soluble in sodium carbonate with evolution of carbon dioxide and yielded a crystalline silver salt. The latter was precipitated in two fractions by the suc- cessive addition of silver nitrate to a solution of the sodium salt, and these fractions, after drying in a vacuum over sulphuric acid, were analyzed: I. 0.0973 sah gave on ignition, 0.0462 Ag. Ag = 47.5. II. 0.5404 of salt gave on ignition, 0.2628 Ag. Ag = 48.6. C6H7OaAg requires Ag = 48.4 per cent. These results established the identity of the above-described substance as levulinic acid. Its formation may be attributed to the action of the sulphuric acid on the sugar contained in the aqueous liquid. The aqueous liquid from which the levulinic acid had been extracted was next treated with just sufficient baryta to remove the sulphuric