Chemistry of Essential Oils

GEBANIACE^E 49$

African

Bourbon

Citronellol.

37 to 43

50 „ 65

Percentage Composition of Alcoh ols.

Geraniol.

40 to 50

20 „ 40

Citronellol.

50 to 60

60 „ 80

The following results are obtained from other varieties of geranium
oil :—

Asian

Corsican

Trappe de Staoiieli

Total Alcohols

as Geraniol.

Per Cent.

68-4

69-8

71-5

Citronellol.

Per Cent.

63-9

30-3

27-9

Percentage Composition of

Alcohols.

Geraniol. Citronellol.,

6-6 r 93-4

57 1 43

61 i 39

72-7

74-1

73-0

73-7

72-1

69-1

39-8

32-9

44-3

45-9

51-0

62-3

Umney 1 gives the following values for a number of geranium oils:—

Frencji

Algerian

Bourbon

Corsican

Asian (1)

.. (2)

It would appear from these results that the citronellol-content of the

Asia Minor oil is undoubtedly the highest, whilst that of Algerian oil is

the lowest. These observations are confirmed by the odour, indicating

that the determination of citronellol-content is not only a useful factor,

but closely follows the nose in judging the value of a particular oil.

The constituents of the various geranium oils are practically identical,

the differences observable being almost entirely of a quantitative nature.

The principal compounds present are the alcohols geraniol and citro-

nellol, together with esters of these two bodies. The term reuniol was at

one time applied to alcohols present in this oil, but it has long been shown

to be merely an impure form of one or other of the two alcohols men-

tioned. Linalol, borneol, terpineol, phenylethyl alcohol, and probably

amyl alcohol are also present in small amounts. The esters present are

principally those of tiglic acid, but small quantities of esters of acetic,

butyric, valerianic, and caproic acids are also present. It is usual to

express the esters of geranium oil in terms of geranyl tiglate.

IJ-a-pinene and /2-phellandrene have been isolated from the oil, as

well as menthone and traces of citral.

The oil is often adult srated with artificial esters which can be searched

for as described under Oil of Bergamot.

1

P. and E.O.R. (1913), 328.