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 ketone is thus seen to agree in its composition and characters with l-methyl-3-cycZohexanone (compare Aschan, Chemie der alicy- klischen Verhindungen, 1906, p. 651), and it appears to be the first instance in which its occurrence in nature has been observed. Further confirmation of its identity was afforded by condensing a portion with benzaldehyde in the presence of a dilute solution of sodium hydroxide, when a dibenzylidene compound was obtained, which crystallised from alcohol in yellow needles melting at 125—126° By the treatment of the above fraction (b. p. 165—170°) with an excess of hydroxylamine hydrochloride and distillation of the product under diminished pressure, a small fraction was obtained which distilled below the boiling point of the oxime (130°/33 mm,). This, on redistillation at the ordinary pressure, boiled at 170—176°, had the odour of limonene, and an optical rotation of - 42° in a 1-dcm. tube. When treated with a slight excess of bromine, and the product crystallised from ethyl acetate, dipentene tetrabromide (m. p. 124°) was obtained. The mother liquors from the crystallisation of the latter compound yielded a small amount of limonene tetrabromide (m. p. 104°) : ^Fraction 170—180°.—This amounted to 7 grams : 0-1170 gave 0-3276 COg and 0-1154 HgO. C = 76-4; H = 10-9. d 16-5°/16-5° = 0-9048; +2°4' in a 1-dcm. tube. This fraction was tested for cineol, but with a negative result. It was distilled twice over sodium, when the greater portion of the oxygenated substances was removed, and was then found to contain small amounts of dipentene and limonene, which were identified by means of their tetrabromo-derivatives: Fraction 180—190°.—The amount of this fraction was 7 grams : 0 0984 gave 0-2748 COg and 0-0981 HgO. C = 76-2; H=ll-1. d 16-5°/16-5°--= 0-9051; an -1-3°12' in a 1-dcm. tube. Fraction 190—200°.—Tins amounted to only 3 grams : 0-1075 gave 0-3039 CO^ and 0-1082 HjO. C = 77-l ; H = ll-2. d 16 5°/16-5°= 0-9023; -t-5°40' in a 1-dcm. tube. Fraction 200—207°.—This was the same in amount as the preceding fraction : 0-1047 gave 0-2966 CO2 and 0-1055 H^O. 0 = 77-2 j H = ll-2. d 16-5°/16-5° = 0-9031 ; + TW in a 1-dcm. tube. The three preceding fractions were too small in amount to admit of further examination. They evidently consisted of mixtures of the constituents of the fractions of lower and higher boiling point. Fraction 207—212°,—The amount of this fraction was 65 grams ;
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