Chemistry of Essential Oils

52 THE CHEMISTKY OF ESSENTIAL OILS

nitric acid a yellow nitro-compound was obtained. When dissolved in

light petroleum and treated with sodium nitrite and acetic acid, no cry-

stalline product separated, but after some hours, a thick, dark-coloured

mass formed at the junction of the liquids. After two days this was

washed in ether and then dissolved in ether-alcohol, from which solution

on evaporation a yellow-coloured substance separated, and after drying

on a porous plate an ochre-yellow powder was left. This darkened much

at about 130° C. and melted with decomposition at about 150° C. It

readily dissolved in nitrobenzene, but did not become blue on heating.

On further investigation it may become possible, perhaps, to prepare a

nitrosonitrite more definite in character with this terpene.

The higher boiling portion of the leaf oil contained the methyl ether

of eugenol, and veratric acid was prepared from it by oxidation. This

methyl ether is the main constituent of the oil from the timber of this

tree.

The crude oil was of a very light amber colour, and the odour some-

what resembled that given by the oil from the wood, thus indicating the

presence of the methyl ether of eugenol, as the constituents of the wood

oil had previously been determined. The leaf oil was very mobile, and

had a low specific gravity. As it was mostly a terpene oil, it was but

little soluble in alcohol, and it required 1 volume of absolute alcohol to

form a clear solution, but it was soluble in all proportions afterwards.

The constituents identified were d-limonene, Z-pinene, dacrydene, and

the methyl ether of eugenol.

An oil was also obtained, to the extent of 0

*

56 per cent., from the

timber of this tree. It had a specific gravity 1*035 at 18°, optical rota-

tion + 1*4°, and refractive index 1*5373 at 23°. Its chief' constituent is

the methyl ether of eugenol, with a small amount of a sesquiterpene,

possibly cadinene.

LEAF OIL OF PHEKOSPH^ERA FITZGEKALDI.

This tree grows freely in New South Wales, and its leaf oil has been
investigated by Baker and Smith.^1
The specific gravity of the crude oil at ff
°
C. = 08705; rotation
aD = + 151°; refractive index at 23° C. = 14841. The saponification
number is 2'4, equal to 084 per cent, of ester as bornyl or geranyl
acetate.
Pinene and cadinene were detected in the oil, and possibly limonene.

LEAF OIL OF PHYLLOCLADUS EHOMBOIDALIS.

This Tasmanian tree is known locally as the Celery Top Pine. Its

essential oil, which has been examined by Baker and Smith,

2

is of par-

ticular interest, as it contains the only solid crystalline diterpene so far

identified. The oil contains Z-pinene, probably mixed with d-pinene, the

diterpene referred to, and possibly a sesquiterpene. '

The diterpene was readily prepared in a perfectly pure condition, so

that it was possible to determine satisfactorily its composition and phy-

sical properties. This well-crystallised body is thus one of the very fetv

members of this class of plant substances which can be prepared from

natural sources in a perfectly pure condition. The oil was obtained by

steam distillation, and contained about 3 per cent, of the solid diterpene.

(^1) The Pines of Australia, 412. (^2) Ibid., 419.