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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    chloride and sodium acetate, when a semicarbazone was obtained which, after crystallisation from methyl alcohol, melted sharply at 171°, the melting point of pulegone semicarbazone. The oil obtained by treating the aqueous bisulphite liquid with alkali likewise distilled at 135—140°/65 mm,, and amounted to 140 grams. It had an optical I’otation of +18°28' in a 1-dcm. tube, and yielded a semicarbazone melting at 171°. It therefore also con- sisted of pulegone, and the somewhat lower rotatory power may be due to its having become partially racemised. The total quantity of pulegone obtained by the above treatment with bisulphite thus corresponds to 24‘1 per cent, of the original oil. Hydrolysis of tlie Oil. The oil from which the pulegone had been I’emoved as completely as possible by the above-described treatment with bisulphite was hydro- lised by boiling it for two hours with a solution of 16 grams of potassium hydroxide in 400 c.c. of 90 per cent, alcohol, the mixture being frequently shaken. After removing the greater portion of the alcohol, a quantity of water was added, and the mixture extracted with ether, the ethereal solution being subsequently washed with water and dried with anhydrous sodium sulphate. After the removal of the ether the product was distilled under a pressure of 60 mm., when the greater portion passed over between 135° and 155°, a small quantity of resinous substance being left in the flask. The weight of the hydrolysed oil thus obtained was 1115 grams. Fractional Distillation of the Oil. The whole of the oil remaining from the foregoing treatment, to which was added the small portion that had been separated for the preliminary examination of the terpenes, was then subjected to repeated fractional distillation under the ordinary pressure, when the following fractions were finally collected : 155—165°, 165—170°, 170—180°, 180—190°, 190—200°, 200—207°, 207—212°, 212—217°, 217—224°, 224—240°, 240—250°, 250—260°, 260—270°, 270—280°, 280—290°, 290—300°, 300—310°. Identification of Pinene. Fraction 155—165°.—This was a colourless, mobile liquid and amounted to 7 grams : 0-1237 gave 0-3536 CO^ and 0-1248 C = 78 0 ; H = ll-2. d 16-5°/16-5° = 0-8867 ; - 3°32' in a 1-dcm. tube. The characters of this fraction indicated that it consisted of a