Chemistry of Essential Oils

264 THE CHEMISTEY OF ESSENTIAL OILS.

PERILLA OILS.

The leaves of Perilla arguta, known in Japan as Shiso, yield an

essential oil of a pale yellow to greenish colour, of a peculiar hay-like

odour, and having the following characters:—

1

Specific gravity .... 0*9265 to 0*939

Optical rotation ... - 90° to - 93°

Refractive index.. 1-4983

Aldehydes 50 per cent, (neutral sulphite method)

The aldehyde present in the oil has been examined by Semmler and

Zaar

2

who find it to be a dihydrocumic aldehyde, Ci 0 H 1 4O, and which

has been named perillic aldehyde. It has the following characters :—

Boiling-point at 10 mm 104° to 105°

Specific gravity at 18° 0*9617

Specific rotation - 146°

Eeiractive index 1*50746

Gattefosse considers that geraniol is present in the oil in the form

of esters. The saponification value is very high, due partially to the

presence of esters and partially to the action of alkali on the aldehyde

present.

The dry leaves of Perilla citriodora yield from 2 to 3 per cent, of

an oil of specific gravity 0*911 to 0'913, containing about 60 per cent,

of citral. From the lower boiling fractions Kondo and Yamaguchi

3

have isolated a body which they term perillene, of the formula C 10 HUO,

and having the following characters :—

Specific gravity at 20° 0*9017

Optical rotation ..........+ 0°

Refractive index at 21° 1*4705

Boiling-point 185° to 186°

It is a complex body containing a furane nucleus. The oil also contains

a sesquiterpene boiling at 251°.

OIL OF HYSSOP.

Hyssopus officinalis is a plant indigenous to the Mediterranean
countries and Central Asia. The fresh plant yields, on distillation, up
to 0*3 per cent, of essential oil having the following characters :—

Specific gravity0925to
Optical rotation+1°,-25°
Refractive index 14730
Acid value 0'8
Ester „ 3
„ „ (after acetylation) 37
An elaborate investigation of hyssop oil has been made by Schimmel
& Co.
4
^e following oils have been distilled by themselves :—
I. Oil from blossoming dry herb: d15o 09377; aD - 22° 3C; acid
number 18 ; ester number 5'8 ; ester number after acetylation 440. Not
soluble in 10 volumes 70 per cent, alcohol; soluble in about 6 and
more volumes 80 per cent, alcohol, with separation of paraffin.
II. Oil from blossoming withered herb : dl5o 09322 ; aD - 22° 23';
acid number 13 ; ester number 3'6 ; ester number after acetylation 37 3;

1

Schimmel's Report, October, 1910, 146.

2

Bericht, 44 (1911), 52.

3

J. Pharm. Soc. Japan (1919), 446, 263. 4 Report, April, 1908, 57.

0*925 to 9'945

+ 1° ,

1*4730 1

0'8 2

3 ,

37 ,

, - 25°

, 1*4860

. 2

, 15

, TO