414 BURGESS AND PAGE: A NOTE ON THE COMPOSITION OF

XLVI1.--A Note on the Composition of Distilled. Oil o,f Limes and a New Sesquiteypene.

By HERBERT EDWARD BURGESS and THEODORE HENRY PAGE. An investigation of terpeneless or concentrated oil of distilled limes *

showed that this product contained about 40 per cent. of free alcohols, The oil was separated by distillation in VQCUO into two fractions.

(1) The lower fraction, which boiled a t about 100-105"/17 mm. and had a sp. gr. 0.930 at 15", was viscous and retained the distinctive odour of the oil. By repeated fractionation, it was obtained in quantities approximating to those found for the alcohols by direct estimation, and had the following constants: sp. gr. 0.934 a t 1 5 O , a-19'30' (100 mm. tube), and nD 1.4806 at 20'.

When cooled in a freezing mixture and sown with a crystal of terpineol, this fraction became nearly solid. After separation and crystallisation from dilute alcohol, the product melted at 35'. I n a supercooled state, the substance had the following constants : sp. gr. 0.941 a t 15', [.ID - 20°, and n, 1.4829 a t 20'; it boiled a t 214'1762 mm.

The terpineol was further characterised by the preparation of certain of its derivatives. Several of these were found to melt a little low, but this is stated to be the case for the derivatives of the active terpineols as compared with those of the inactive variety.

The nitrosochloride was obtained in practically quantitative yield by adding hydrochloric acid diluted with glacial acetic acid to a well- cooled solution of the terpineol and amyl nitrite in glacial acetic acid, the product being precipitated with ice-water. After recrystallisation from ethyl acetate, it melted at 105-106'.

* The oil obtained after distilling off the terpcnes.

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DISTILLED OIL OF LIMES AND A NEW SESQUITERPENE. 415

The nitroleanilide,'prepared from the preceding compound by warming with an alcoholic solution of aniline, crystallised from alcohol and melted at 150-151'.

The phenylurethane slowly separated from a mixture of equal volumes of terpineol and phenylcarbimide. After crystallisation from alcohol it melted a t 111'.

The terpineol was successively oxidised with 2.5 per cent. potassium permanganate solution and chromic acid mixture (sp. gr. 1-25), the latter reagent being carefully added to the first oxidation product dis- solved in a little water. The oil, which separated, solidified after some days, and when recrystallised from water melted at 62". This product corresponds with the ketolactone from terpineol (m. p. 35O), and was further characterised by conversion into the oxime (m. p 77').

These results indicate tha t lsvorotatory terpineol (m. p. 35") forms a considerable proportion of the oxygenated compounds in distilled oil of limes.

Although the peculiar odour of distilled oil of limes is attached to the terpineol fraction, the terpineol isolated is either practically odourless or has a faint odour of lilac. The aroma is probably due to an isomeric liquid terpineol having a slightly lower boiling point, but a t present this supposition is not supported by conclusive evidence.

(2) The second fraction boiled a t 130-140°/17 mm., and had a lower sp. gr. than the first, the value of this constant being under 0.900. This fraction was found t o give only a slight action with sodium, and hence consisted almost entirely of hydrocarbons, which from their boiling point seemed to be sesquiterpenes. It was diluted with two volumes of dry ether, saturated with hydrogen chloride, and left for several days. On evaporating off the diluent, crystals separated which were collected, and, after crystallisation from ethyl acetate, melted constantly a t 79-80'. This product forms colourless crystals readily soluble in ethyl acetate, acetone, or ether, but less so in alcohol, acetic acid, or chloroform; it is characterised by a remarkable power of crystallisation, and is never obtained in an oily state, although its melting point is comparatively low,

The hydrochloride was mixed with 18 parts by weight of sodium acetate and 6 parts of acetic acid, and heated nearly to the boiling point for an hour. The crystals first dissolved, but after a time sodium chloride separated. The cooled mixture was then poured into water, mashed, and distilled in steam. The dried distillate was fractionated, the last time over sodium, and obtained as a colouxless oil with a slight, but peculiar odour; it resinified with great readiness, even when left in a partially filled flask. It boiled at 131' under 9 mm. and at 262-263' (uncorr.) under 756 mm. pressure, i n the latter case with slight decomposition ; the following constants were

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416 PERKIN : 8-KETOHEXAHYDROBENZOIC ACID.

also determined : sp. gr. 0.873 a t 15', [a],, +, O', nD 1.4935 at 1 5 O , an(\ 1.4910 at 19.5' ; mol. refract. 68.2, whereas CI,H,, (with three double linkings) requires 67-76,

0,2768 gave 0.8970 CO, and 0.2986 H,O.

In dilute solution in acetic acid, the hydrocarbon combined with

C = 88.38 ; H = 11.99. C,,H,, requires C = 88.24 ; H = 11 *76 per cent;.

approximately 6 atoms of bromine.

The hydrochloride gave C1= 34.2. C,,HZ4,3HC1 requires 34.0 per cent.

This was the only derivative successfully prepared. The nitroso- chloride, nitrite, bromide, and acetate were unsatisfactory,

From the above data, it seems apparent that distilled oil of lime3 con- tains a sesquiterpene, not hitherto described, and differing materially from the other members of the series, especially in specific gravity, which is much lower than the usual value for sesquiterpenes, but ap- proximates t o those found for olefinic or partially oletinic sesquiterpenes.

The name " Zirnene " is suggested for this sesquiterpene, as having first been found in oil of limes.

Limene is also present in hand-pressed lime oil and in lemon oil i n the fraction boiling between 120' and 140' under 9 mm. pres- sure. The characteristic hydrochloride (m. p. 79-80') was readily obtained by saturating this fraction with hydrogen chloride. Other oils of this series are being examined with the view of ascertaining whether limene is present or not.

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