The constituents of the essential oil of American pennyroyal / by Marmaduke Barrowcliff.

  • Barrowcliff, Marmaduke.
Date:
1907
Catalogue details

Licence: In copyright

Credit: The constituents of the essential oil of American pennyroyal / by Marmaduke Barrowcliff. 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.

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    This substance was thus identified as salicylic acid. As the original oil had previously been extracted with sodium carbonate, this acid could not have existed in it in a free state, and was probably present in the form of methyl salicylate, which had become hydrolysed in the process of isolation. Preliminary Examination of the Terrenes.—In order to test for the presence of an olefinic or other unstable terpene, the oil which had previously been extracted with sodium carbonate and caustic alkali, as above described, was distilled under 60 mm. pressure, and the portion which passed over below 120° (about 50 c.c.) separately collected. This was again distilled under the same pressure, when it was resolved into the following fractions: below 105°, 105—120°; above 120°. The fraction boiling below 105°/60 mm. had the odour of pinene and a density of 0’8508 at 15°/15°, which indicated the absence of any olefinic terpene. The fraction 105—120°/60 mm. was specially tested for phellandrene, but with a negative result. All the above fractions were subsequently added to the main portion of the oil after the latter had been hydrolysed. Isolation of PvXegone. The entire portion of the oil boiling above 120°/60 mm. was treated with a solution of sodium bisulphite according to the method employed by Baeyer for the separation of pulegone from the oil of Mentha Pulegium {Ber.y 1895, 28, 652), and the mixture actively shaken for ten days. This effected the separation of a large quantity of a crys- talline bisulphite compound, which was removed by filtration and washed with alcohol and ether. The uncombined oil contained in the filtrate and washings was extracted with ether, and the ethereal solu- tion dried with anhydrous sodium sulphate. After the removal of the ether the residual oil was rectified under 60 mm. pressure, when a small quantity of resinous matter remained in the flask. The further treatment of this portion of the oil is subsequently described. The solid bisulphite compound and the aqueous filtrate therefrom, which had been freed from uncombined oil, were then separately decomposed by wai’ming with a solution of potassium hydroxide, and the liberated ketone extracted with ether and dried. That obtained from the solid bisulphite compound distilled at 135—140°/65 mm. as a colourless oil, which acquired a slight yellow colour on standing, and amounted to 390 grams : 0T027 gave 0 2966 COg and 0-0979 HgO. C = 78-8; H = 10-6. . requires C = 78-9 ; H = 10‘5 per cent. <^ = 0-9377 at 20°/20°; ud -i-19°50' in a 1-dcm. tube, whence [a]u +21-15°. A ortion of this ketone was treated with semicarbazide hydro-