Licence: Attribution 4.0 International (CC BY 4.0)
Credit: The constitution of umbellulone. [Pt. I] / by Frank Tutin. 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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![subsequent oxidation of the resulting alcohol with a limited amount of chromic acid, a ketone, CjqH^qO (m. p. of semicarbazone, 155—156°), is obtained, for which the name fi-dihydroumhellulone is proposed. This ketone has an odour almost indistinguishable from that of pulegone, and is unsaturated ; it is evident, therefore, that when umbellulone is reduced by sodium and alcohol, the ethylenic linking remains unattacked, whilst one of the carbon rings becomes ruptured by the addition of two atoms of hydrogen. The rupture of one of the closed rings contained in bromodihydro- umbellulone, CjoH].^OBr, was shown by Lees to take place when this compound is reduced by sodium and alcohol, but the “ tetrahydro- umbellulol ” obtained is undoubtedly a mixture, as the ketone resulting from its oxidation yielded semicarbazones of m. p. 150° and 171° respectively. It is impossible to say whether this mixture consists of structural or only stereo-isomerides. Experimental. The umbellulone employed in this investigation was obtained from the essential oil of Umhellularia Ccdifornica, which had been specially distilled for this purpose. It was found to have the following constants: d = 0'9453 at 20°/20°; an -21°55' in a 1-dcm. tube. Two thousand grams of this oil were freed from acids and phenols by shaking with potassium hydroxide, after which the washed and dried oil was submitted to a prolonged fractional distillation, and the following fractions were eventually collected. Below 190°, 190,—200°, 200—215°, 215—225°, 225—235°, 235—245°, 245° + . The fraction 215—225° weighed 580 grams; it had aj, - 34°4' in a 1-dcm. tube, and a specific gravity of 0 9600 at 15°/15°. On treatment with semicarbazide, it gave from 50—60 per cent, of the theoretical yield of semicarbazidodihydroumbellulonesemicarhazone (m. p. 216°), and evidently represented fairly pure umbellulone. Except where otherwise stated, this fraction boiling from 215—225° was the “ umbellulone ” used throughout this investigation. Oxidation of Umbellulone with Potassium Permanganate. One hundred and twenty grams of umbellulone were shaken into an emulsion with 1500 c.c. of water and the mixture cooled by the introduction of powdered ice. A 4 per cent, solution of potassium permanganate was then gradually added, with vigorous shaking, until the pink colour produced was only slowly discharged. In this manner, it was found that an amount of permanganate equivalent to rather less than four atomic proportions of oxygen was](https://iiif.wellcomecollection.org/image/b22402019_0011.jp2/full/800%2C/0/default.jpg)
