The chemistry of essential oils and artificial perfumes / by Ernest J. Parry.

  • Parry, Ernest J. (Ernest John)
Date:
1908
Catalogue details

Licence: In copyright

Credit: The chemistry of essential oils and artificial perfumes / by Ernest J. Parry. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    Four isomeric menthones may exist, with eight corres- ponding isomeric menthols {vide supra). But whichever menthone is converted into menthol, natural laevo-menthol is the predominating resulting compound. Menthone has been synthesised by Kotz and Hesse from methyl-hexanone and ethyl oxalate. GineoL, C10H18O.—This body, which is somewhat isolated in its chemical relationships, may well be discussed here. It has been described under several names, the best known being that now usually adopted, viz., cineol; also cajuputol (from its occurrence in oil of cajuput) and eucalyptol (from its occurrence in oil of eucalyptus). It is found in nature in very large quantities in the above-mentioned oils, as well as in many others, notably wormseed, lavender (English) and spike-lavender oils. It results also by the treatment of terpin hydrate with acids. Wallach and Brass, who first characterised it as a definite compound, gave the following method for its preparation. A current of dry hydrochloric acid gas is passed into rectified wormseed oil. The resulting crystalline magma of cineol hydrochloride is pressed at low temperature to remove as much as possible of adhering liquid, and the crystals are treated with water and steam distilled. The crude cineol is again subjected to this treatment when the pure body is obtained. When pure, cineol is an optically inactive liquid, solidifying at low temperatures and melting at - 1°, with a characteristic camphoraceous odour. It boils at 176°, and has a specific gravity 930. Its refractive index is 1*4596. Scammell proposed its separation by means of a definite crystalline compound with phosphoric acid. This body has the composition Ci0HlsO . H3P04. The use of phosphoric acid is the basis of the 1898 British Pharmacopceial test for cineol in essential oils. Cineol forms a number of crystalline derivatives, amongst which may be mentioned the hydrobromide, C]0H18O. HBr . ,