456 THE CHEMISTEY OF ESSENTIAL OILS
METHYL-NONYL KETONE.Boiling-point 229° to 233° (75^9 mm.)
Boiling of the ketone regenerated from
the semi-carbazone .... 231'5° to 232-5° (761 mm.)
Specific gravity d ?^° 0-8263
Melting-point of the semi-carbazone.. 122°Methyl-nonyl ketone is capable of being estimated quantitatively by
the phenyl-hydrazine method (see under lemon oil), and the same applies
to methyl-heptyl ketone. It should be remembered that in rue oil both
the ketones are always present in varying proportions. Hence the quantity
of phenyl-hydrazine which has been used only affords an approximate
estimation of the quantity of the ketones, and it must at the same time be
ascertained, by determining the solidifying-point, which of the two ketones
predominates in the oil, and whether it will bj more practicable in esti-
mating to use as a basis the molecular weight of methyl-nonyl ketone
(170) or that of methyl-heptyl ketone (142).
OIL OF BUCHU.
Several species of Barosma are known by the name Bacini, and from
the leaves of these the oil is distilled. The chief of these are, Barosma
serratifolia, Barosma betulina, and Barosma crenulata. The yield of oil
is from 1 to 2 per cent. The recent researches of Kondakoff^1 and
Bialobrzeski
2
have proved that the oil contains several constituents.
These are diosphenol Cj0H 16 O 2 , the chief optically inactive compound in
the oil; the terpenes limonene and dipentene, and a ketone G 10 H 18 O
which is probably laevo-menthone. Diosphenol is a crystalline solid,
melting at 83° and boiling at 232°. It occurs only to a very small extent
in the oil distilled from the leaves of Barosma serratifolia, whereas that
from Barosma betulina contains so much that crystals separate at ordinary
temperature.
The ketone C 10 H 18 O is a slightly laevo-rotary liquid boiling at 206° to
209°, of specific gravity *902, of agreeable peppermint like odour, and is
probably identical with menthone. Pure diosphenol can be obtained from
the oil by extraction with soda solution and decomposition of the alkaline
liquid with an acid, and recrystallising the crude diosphenol from a
mixture of alcohol and ether. Buchu oil is often adulterated with turpen-
tine and possibly other oils. It is used to a small extent in medicine.
The oils have the following characters :—11(i1'<>,s*ma Betidin<t.
Specific grav it y 0'935 to 0-970
Optical rotation. 15° ,, - 48°
Kefractive index 1-4740 „ 1-4H65
Diosphenol (by NaOH absorption) ... 17 to 30 per cent.I la mania Crenitlata.
Specific gravity ......... 0
1(
J36
Optical rotation - 15° 20'
Kefractive inde x 1*4800
1
Jour. f
r. Chem., ii. 54 (1896), 41-33.
i
Pharm. Zcit. Itu-ss., 35 (1896), 417, 433, 441).