Chemistry of Essential Oils

238 THE CHEMISTEY OF ESSENTIAL OILS

Specific gravity.

Optical rotation.

Refractive index

Carvone

Specific gravity 0

Optical rotation•

Carvone

Linalol

Austrian Spearmint Oil.^1

Russian Oil.

0-936 to 0-952

• 38° „ - 50°
  1-4890 „ 1-4930
  61 to 72 per cent.

0-880 to 0-890

• 20° „ - 28°
  5 to 10 per cent.
  50 „ 60
  According to E. K. Nelson, an American oil which he examined had
  the following characters :—

Specific gravity at 25°.

Optical rotation

Refractive index at 25°.

Ester value

,, (after acetylation)

0-9290

- 52-16°

1-4866

12-4

36-4

The oil contained 66 per cent, of carvone, phellandrene, and
Z-limonene, and dihydrocarveol acetate. Esters of acetic, butyric, and
caproic or caprylic acids are also present.
Elze,
2
after removing the carvone from a German spearmint oil,
obtained an oil with a more intense spearmint odour than the original
oil. It had a specific gravity 0-917 and optical rotation - 28°. It
contained 18 per cent, of esters and on fractionation yielded the follow-
ing results :—

A

B

C

D

E

Boiling-point

(4 mm.)

40°

45°

75°

80°

85°

to 45°

„ 75°

„ 80°

„ 85°

°„100°

Percentage.

15-0

15-0

24-0

7-5

35-0

0-860

0-894

0-930

0-935

0-940

Rotation.

- 27° 30'

- 25°

- 24°

- 30° 50'

- 40°

Ester-

content.

2-8 %

19'0 „

31-0 „

The author was able to prove the presence, in fraction A, of ^-phel-
landrene, which was identified by its nitrosite (melting-point 105° to
105^°) as well as by its constants (boiling-point 175° to 176° [755 mm.];
d1&0 0'8575°; a - 26° 0'). Fraction E, which possessed a marked odour
of spearmint, was saponified. Acetic acid, together with small propor-
tions of valeric acid (probably isovaleric acid?) were identified. The
alcoholic part consisted to the extent of 15 per cent, of dihydrocuminic
alcohol (d 150 0-9539; a - 30° 15'), which yielded a naphthyl urethane
melting at 146° to 147°, and also, when oxidised with Beckmann's
mixture, an aldehyde (melting-point of the semi-carbazone 198° bo 199°),
and an acid, melting at 132°. When fraction E was saponified the
typical spearmint odour disappeared; hence, in Size's opinion, the
dihydrocuminic acetate is the carrier of the odorous principle of
the oil.

F. Rabak

3

has carried out an investigation on the influence of the

1

According to Schimmel & Co.

*

Chem. ZeiL, 34 (1910), 1175.

3

Jour. Ind. Eng. Chem. (1918), 10, 4, 275.