Chemistry of Essential Oils

455

SYRIAN OIL.

Specific gravity

Optical rotation

Refractive index

Solidifying-point

0-841

- 0° 28'

1-4329

- 1-9°

A sample of the oil from Ruta montana, which had the following

characteristics—

Specific gravity

Optical rotation

Refractive index

Melting-point.

0-8344

+ 0° 18'

1-4318

10-5°

was fractionated at ordinary pressure,^1 with the following results:—

20 per cent.

30

25

15

10 „ Res.

Boiling-point.

219-5° to 224°

„ 226°

„ 227°

„ 228-5°

above 228-5°

Specific Gravity.

0-834

0-832

0-832

0-836

Refractive

Index 20°.

1-4307

1-43

1-4297

1-4305

1-4471

Melting-

point.

11 °

14°

14-5°

14 °

—

The characteristic constituents of the oils of rue are the ketones methyl-
nonyl-ketone, CH 3. CO. C 9 H 19 , and methyl-heptyl-ketone. Of these
methyl-nonyl-ketone predominates in the French oil and in the oil of
Ruta montana, whilst methyl-heptyl-ketone is present in the oil of
Ruta bracteosa.
Schimmel found traces of a basic substance present in the oil, which
is probably the methyl ether of methyl-anthranilic acid, and would
account for the fluorescence of the oil. Van Soden has examined all
Algerian oil of rue, and found it to have a specific gravity 0*84:2 and
optical rotation - 5°. It did not solidify even at - 15°. Its principal
constituent was found to be methyl-heptyl-ketone, whilst only a small
quantity of methyl-nonyl-ketone was present. This is evidently the oil
of Ruta bracteosa. A German oil investigated by Houben was found to
contain both ketones, the methyl-nonyl-ketone predominating. Traces of
caprylic acid and of a phenyl were detected. Power and Lees have ex-
amined an oil, probably of Algerian origin, and found present a basic sub-
stance having an odour of quinoline, traces of methyl salicylate and of
salicylic acid. They also found valeric acid (as esters?), laevo-pinene,
limonene, and cineol. The alcohols corresponding to the ketones were
also found present.
Bergaptene has also been found in traces in the oil.
The characters of the ketones above mentioned are as follows :—

METHYL-HEPTYL KETONE.

Boiling-point ....

Specific gravity ....

Melting-point of the semi-carbazone

194-5° to 195-5° (763 mm )

d **! 0-8296

119° to 120°

(^1) Evans' Analytical Notes (1912), 65.