Chemistry of Essential Oils

PIPEEACE^E 109

PIPERACE/E,

CUBEB OIL.
This oil, which is official in the British Pharmacopoeia, is distilled
from the fruit of Piper cubeba (Cubeba officinalis Miq.). The cubebs
of commerce are the dried unripe fruits, which resemble ordinary black
pepper in appearance, except that they are rather lighter in colour;
they are chiefly imported from Batavia and Singapore.
The berries are coarsely ground and distilled with steam, yielding
from 10 to 18 per cent, of volatile oil. This is of a faint greenish or
greenish-blue colour, and of very characteristic and somewhat aromatic
odour. The colour has been stated to be due to copper, but this is
erroneous, as the higher fractions contain a blue oil in greater or less
quantity, which determines the tint of the liquid.
The characters of normal cubeb oil are as follows:—
Specific gravity at 15°.
Optical rotation.
Refractive index at 20°

0-912 to 0-930

• 25° „ - 42°
  1-4930 „ 1-4970
  The solubility in 90 per cent, alcohol is very variable, some samples re-
  quiring only 1 to 2 volumes, others up to 10 volumes, to effect solution.
  A fractional distillation of the oil yields valuable results, from 65 to
  80 per cent, distilling between 250° and 280
  °
  . Four pure samples ex-
  amined in this manner by Messrs. Oranje l gave the following results :—
  i.
  Yield, 14 per cent. oil.
  Specific gravity (15°), 0*9268 ; optical rotation - 33-70°.
  Fractionation of 50 grms. :—
  Below 250°.
  250° to 260°
  260° „ 270°
  270° „ 280°
  Residue

0*0 grms. =

11-7 „ =

26-8 „ =

4-7 „ =

6-8 „ =

0-0

23-4

53-6

9*4

13'6

per cent.

: 1

Below 250°.

250° to 280°

Residue

0-0 per cent

26-8 „

13'6 „

50-0 100-0

2.

Yield, 9-5 per cent. oil.

Specific gravity (15°), 0-9258; optical rotation - 27-40°.

Fractionation of 40 grms.:—

Below 250°. O'O grms. = 0-0 per cent.

250°.to260° 10-9 „ = 27-3

260° „ 270° 15-8 „ = 39'5

270° „ 280° 6-4 ., = 16*0

Residue. 6'9 „ = 17'2

Below 250°.

250 to 280°.

Residue

100-0

0*0 per cent.

82-8 „

17-2 „

40-0 100-0 100-0

3.

Yield, 15-0 per cent. oil.

Specific gravity (15°), 0-9226; optical rotation - 34-60°

Fractionation of 50 grms.:-

Below 230°.

230° to 240°

240° „ 250°

250° „ 260°

260° „ 270°

270° „ 280°

Residue

0'O grms. =

4-0 „ =

5-0 „ =

27-4 „ =

7-0 „ =

1-7 „ =

4-9 „ =

0-0 per cent. |

8-0 „ \

10-0 „ j

54-8 „ 1

14-0 „ \

3-4 „ J

9-8

Below 250°.

250° to 280°

Residue

18*0 per cent.

72-2 „

9-8 „

50-0 100-0 100-0

(^1) P. and E.O.R. (1914), 372.