A Manual of the Chemistry of the Carbon Compounds

3SS THE CHEMISTRY OF
In these two last reactions the carbamine is first formed, but under
the influence of heat converted into the more stable nitrile,
Beiizonitrile is a colourless, oily, and refractive liquid, boiling at
191°, and smelling like bitter almonds. OR heating it with alcoholic
potash, it yields ammonia and potassium benzoate, and nascent
hydrogen converts it into benzylamine;—
C8H6.CN + 2H, = C0H6,CHj!.NH2
RitroltmmMrile C?H4(N0,j)CN is obtained by dissolving the nitrite
iu fuming nitric acid Ik crystallizes in white needles; reducing
agents convert it into amidobenzonitrUe C0H4(NH2)CN, crystallizing
in long prisms, melting at 52°, and boiling at 290°, This base forms
crystalline salts j by heating it with strong hydrochloric acid, it yields
ammonium chloride and amidobenzoic acid.
Benzaliehyde (LH^C/OH is the chief constituent of oil of bitter
almonds. This oil does not exist in the free state in these seeds, but
as glucoside called amygdalin, which, under the influence of a ferment,
is resolved into benzaldehyde, pruasic add, and glucose (see Glucosides).
Benzaldehyde is also formed by oxidizing benzyl alcohol, and
by distilling a mixture of calcium benzoate and formate:—
C6H6,CO.OH + CHO.OH = CeH^COH + CO2 + H,0
Another reaction by which this aldehyde is produced consists in
passing the vapour of benzoic acid over heated zinc-dust;—
CgHu.CO.OH + Za = C6HS.COH + ZnO
To obtain the pure aldehyde from oil of bitter almonds, it is shaken
with a cold saturated solution of acid sodium sulphite; the compound
CJHJ.CH < QQJT being formed, which separates out in crystals.
After being washed with cold alcohol, to remove prusaic acid, the
compound is decomposed by distilling it with a solution of sodium
carbonate.
Pure benzaldehyde is a limpid and very refractive liquid, possessing
a very characteristic smell, and boiling at 180°, tt readily absorbs
oxygen, being converted into benzoic acid; this oxidation takes place
quickly by heating it with dilnte nitric acid, whilst faming nitric acid
forms nUrohemaUehi/de C8H4(N0JJ)CO1I, a crystalline solid, which
volatilizes on heating.
When benzaldehyde is distilled with phosphorus pentachloride, it
yields henzykiu dichloride C^Hg-CHClj, a colourless liquid boiling at
215°. The same compound is produced by the further action of
chlorine on boiling benzyl chloride. It may be reconverted into the
aldehyde by heating it with caustic potash or mercuric oxide;—
+ HgO = CaH5.CHO + HgCl,