298 THE CHBMISTEY OF ESSENTIAL OILS
1'0891 at 21°, optical rotation + 28°, and refractive index 1-53043.
Costic acid, C 15 H 22 O 2 , of specific gravity 1-0501, was also found in the
free state. It is an unsaturated bicyclic acid forming a methyl ester
boiling at 170° to 175° at 11 mm. In the fraction boiling at 190° to 200°
at 11 mm. there was found a lactone of the formula C 15 H 2 2O 2 , which
has been named dihydro-costus-lactone. A new sesquiterpene alcohol,.
C 16 H 24 O, which the authors have named costol, was also isolated. It
forms a phthalic acid ester, from which it can be prepared in the pure
condition. It was then found to have the following characters :—
Boiling point at 11 mm 169° to 171°
Specific gravity at 21° 0'983
Optical rotation +13
Refractive index 1-5200
By oxidation with chromic acid it yields an aldehyde. By the action of
phosphorus trichloride it yields costyl chloride, which, by the loss of
HC1, is converted into the sesquiterpene isocostene, C 15 H 24. The authors
have also obtained a hydrocarbon of the formula C 17 H 28 , to which they
have assigned the name aplotaxene, belonging to the aliphatic series,,
and two sesquiterpenes which they have named a-costene and 6-costene^
which have the following characters :—
a-Costene. /3-Costene.
Boiling-point.. 122° to 126° (12 mm.) 144° to 149° (18 mm.)
Specific gravity.. 0-9014 at 21° 0-8728 at 22°
Rotation ... - 12° +6°
Refractive index.. 1-49807 1-4905
The approximate composition of the oil is :—
Camphene about -04 per cent,
Phellandrene,,0-4Terpene alcohol
a-Costene
0-Costene
Aplotaxene
Oostol.
Dihydrocostuslactone
Costus lactone
Costic acid
0-2
6-0
6-0
20-0
7-0
15-0
11-0
14-0
OLLS OF EUPATOBWM.Dog fennel oil is distilled from the herb Eupatorium foeniculaceum,.
(E. capillifolium), a plant distributed throughout the northern parts of
America. The oil is of a golden yellow colour and pepper-like odour,
Millerl has recently examined a number of samples distilled in Alabama,
the yield of oil being from0*8 to 1*35 percent. He found eleven samples
of the oil to have the following characters (see next page), the rota-
tion varying considerably according to season.
An oil distilled in Florida has been described, having an optical
rotation of + 17° 50', and containing much phellandrene. Miller's more
recent work makes the authenticity of this sample doubtful. The oil
contains traces of aldehydes and ketones, and, probably, of salicylic acid.
The principal constituent of the oil is the dimethyl ether of thymo-
hydroquinone. Phellandrene, borneol, bornyl acetate, linalol and
sabinene (?) are present in the oil.
Eupatorium triplinerve, a plant indigenous to tropical America, and
1
Bull. University of Wisconsin, 693 (1914), 7.