316 THE CHEMISTEY OF ESSENTIAL OILS
By splitting off hydrochloric acid with sodium ethylate a hydro-
carbon possessing the following properties was recovered from the
chloride: Boiling-point 268° to 272° (the bulk 268°); duo 0-9232;
dsso" 0-9196; [a]D + 49° 30'; wD2o° 150483. The hydrocarbon which
was obtained from the dihydrochloride is again converted by means of
hydrochloric acid in ethereal solution into the dihydrochloride, melting-
point 72° to 74°.
It is therefore possible to obtain the hydrocarbon in the pure state
by means of the dihydrochloride, that is to say, in so far as it is at all
possible, in view of the possible formation of isomerides, to regenerate
a hydrocarbon from a chloride.
Selinene has been investigated by Semmler and Eissel who give
the following details:—
Selinene has a specific gravity 0919, optical rotation + 61° 36',
refractive index 1-5092, and boiling-point 128° to 132° at 11 mm. It is
shown to be a bicyclic doubly unsaturated hydrocarbon. On reduction
it yields tetrahydro-selinene, C 15 H 28 , of specific gravity 0'8881, rotation
- 7°, refractive index 1-48259, and boiling at 126° to 128° at 11 mm.
Selinene yields a dihydrochloride, which, when treated with calcium
hydroxide, yields the alcohol selinenol C 16 H 20 O. This body boils at
155° to 163° at 19 mm., and has a specific gravity 09627, refractive
index 1-50895, and optical rotation + 52° 36'. If the hydrocarbon be
regenerated the resulting sesquiterpene has a slightly higher optical
rotation, due possibly to isomerisation. The two sesquiterpenes were
oxidised with ozone in order to throw light on their constitutions.
Natural selinene, to which Semmler assigns the name /3-selinene, yields
a large amount of an indifferent body, which yields a disemicarbazone
melting at 228°. From this the diketone was recovered, and found to
have the formula C 13 H 20 O 2. It boils at 178° to 180° at 11 mm., and has
a specific gravity 10566, refractive index 1*49994, and optical rotation - 15°. Eegenerated selinene, or or^o-a-selinene, boils at 128° to 132°
at 11 mm., and has a specific gravity 09190, refractive index 15092,
and optical rotation + 61° 36', yields only a small amount of this
diketone, but a large amount of an acid which is termed methyl-
selinene diketo-monocarboxylate C 15 H 24 O 4 , boiling at 185° to 190° at
11 mm., and having a specific gravity 10635, refractive index 147889,
and rotation + 4° 24'. These facts are accounted for on the hypothesis
that during the elimination of hydrochloric acid from the dihydro-
chloride a double linkage has been displaced into the ring.
An oil from the herb and seed of the wild celery (Ache des marais),
distilled in the South of France, possessed the following constants:—
Specific gravity 0871
Optical rotation + 58° 30'.
Refractive index 1-4771
Acid number .......... 1-8
Ester „ 41-5
After rectification with steam (in the course of which process a
residue of 77 per cent, remained) its properties had undergone con-
siderable change: dl50 0-8541; aD + 70° 55'; n^ 1*47489. Soluble in
6 volumes and more of 90 per cent, alcohol with slight turbidity.
An Algerian oil distilled from wild plants had the following char-
acters :—•
1
Berichte, 45 (1912), 3301.