A Manual of the Chemistry of the Carbon Compounds

THE CARBON COMPOUNDS, 327
Thio-anilineS\ Q 6 g*3.—This bi-acid base is formed together
with hydrogen sulphide by heating aniline and sulphur together with
oxide of lead, the latter being added to remove the hydrogen
sulphide as soon as it is formed, because it has a decomposing action
on thio-aniline,
Thio-aniline crystallises from a hot aqueous solution in long, thin
silky needles, melting at 104°; when more strongly heated, they are
decomposed. With acids it combines, forming salts which all crystallize
very readily. On adding potassium dichroinate to the solution of one
of the salts, violet flakes, soluble in alcohol, are precipitated Thioaniline
dissolves in concentrated sulphuric acid, forming a red or
blue solution, which, when poured into water, yields a beautiful red
liquid.
DIAMIDOBENZENES C0H4 j
Orthodiamidobenzene is formed by the reduction of orthonitraniline;
it is readily soluble in water, and forms colourless crystals, melting at
140°, and boiling at 267°.
Paradiamidobenzene has been prepared by reducing dinitrobenzene
or paranitraniline with tin and hydrochloric acid. On decomposing
the hydroohloride thus formed with soda, the base separates out
as a liquid, which gradually solidifies to a crystalline mass. It
melts at 63°, and boils at 287°. It absorbs oxygen from the air, and
changes soon into a brown mass,
Metadiamidobenzene is obtained from metanitraniline. It forms
brilliant white plates, melting at 99° and boiling at 252°.
TRIAMIDOBENZENE
"When triamidobenzoic acid is heated, it is resolved into carbondioxide
and triamidobenzeno, a crystalline solid, melting at 104°, and
boiling at 330°. Ita concentrated aqueous solution has an alkaline
reaction, and gives, with ferric chloride, a violet precipitate, which
soon turns brown. It reduces an ammoniacal silver solution, and
gives, with sulphuric acid containing a trace of nitric acid, a deep
blue liquid. Triamidobenzene forms crystalline salts, containing two
equivalents of an acid,
A20-DERIVATIVE8 OF BENZENK.
Azoleiizene Q 6 TT 6 f N2 is obtained by distilling nitrobenzene with
an alcoholic solution of potash. In this reaction the alcohol acts as
a reducing agent, being oxidized to aldehyde. Azobenzene is also
2