530 THE CHEMISTEY OF ESSENTIAL OILS
for camphor with semi-carbazide, proved to be camphor-free. The
borneol, after being purified by recrystallisation from light petroleum,
melted at 204°. Its chloroform solution was dextro-rotatory.
With the object of setting free the borneol from the higher boiling
fractions of the oil and from the mother liquors, these latter were benzoy-
lated with benzoyl chloride, with the aid of pyridine. The oil which was
driven off in the steam-current by this manipulation, and which was not
esterified, proved to consist substantially of Z-a-terpineol, melting-point
35°. A fraction gave the following constants: dl5 0 0-9379, aD - 8° 2'.
The resulting phenylurethane melted at 112°. After saponification of
the residue of steam distillation no alcohols other than borneol were
discovered. The highest boiling fractions, boiling-point 102° to 112° (4
to 5 mm.), consisted only of sesquiterpenes. None of them, when
warmed, reacted with strong formic acid; hence no sesquiterpene alco-
hols were present. One fraction was found to possess the following
constants: boiling-point 102° (4 to 5 mm.), 256° to 260° (ordinary
pressure); d 150 0-9200; aD - 137° 12'; nD200 1-50111. This is probably
cadinene.
OIL OF GURJUN BALSAM.
The so-called " wood oil" or gurjun balsam oil is the product of the
distillation of the oleo-resin from several species of Dipterocarpus. Gurjun
balsam resembles copaiba in its general characters, and is often used to
adulterate the latter drug. On distillation from 45 to 70 per cent, of
essential oil is obtained, which has the following characters :—
Specific gravity 0-915 to 0-930
Optical rotation - 35° „ - 135°
Refractive index ........ about 1-5050
Acid value 0 to 1
Ester ,„ 4 „ 8
„ „ (after acetylation) 6 ,, 6 „ 10
This oil is not employed commercially to any extent, but is used from
time to time for adulteration purposes. For example, it has recently been
detected as an adulterant of palmarosa oil, and in otto of rose in traces,
due to the adulteration of the last-named oil with geraniol manufactured
from adulterated palmarosa oil.
It can be detected by dissolving 5 to 10 drops of the suspected oil in
5 c.c. of glacial acetic acid containing 5 drops of nitric acid. In the pre-
sence of gurjun oil a red-violet colour is developed, which appears within
a minute if more than mere traces are present.
The principal constituent of the oil is a sesquiterpene or mixture of ses-
quiterpenes. These have been investigated by Deussen and Philipp,
1
who
showed that the sesquiterpene mixture consisted principally of two ses-
quiterpenes which they named a-gurjunene and /2-gurjunene. Semmler,
Spornitz, and Jakubowicz^2 have also investigated these sesquiterpenes,
and consider that both of them are tricyclic compounds. Deussen and
Philipp also showed that, by the oxidation of the oil in acetone solution
by means of potassium permanganate, a ketone, C 15 H 24 O, which they
named gurjun-ketone, is formed, and which yields a semi-carbazone
melting at 234°, which serves as a useful means of identifying the oil in
mixtures.
The following method of identifying this oil (for example in otto of
(^1) Annalen, 369 (1909), 56; 374 (1910), 105. (^2) Berichte, 47 (1914), 1029, 1141.