A Manual of the Chemistry of the Carbon Compounds

346 THE CHEMISTRY OF
action is over, the product is distilled, and the toluene isolated by
fractional distillation. Pure toluene is also produced by distilling
the isomeric acids C6H4(CHg)CO2H, and similar acids, with lime.
Toluene is a limpid liquid, boiling at 111°, and smelling like
benzene. It has the specific gravity 0*88 at 0°, and does not solidify
at — 20°, On oxidation it yields benzene acid.
SOBBTrrUTION-PEODUCTB OF TOLUENE.
When chlorine is passed into toluene, and the liquid is kept cold
during the action, or when chlorine acts on the hydrocarbon in the
presence of iodine, only the hydrogen in the aromatic nucleus is
replaced, whilst the action of pure chlorine on the boiling hydrocarbon
produced only substitution in the methyl-group.
The chlorine in these latter compounds is easily replaceable by
other elements or radicals, whilst the substitution-products containing
the chlorine in the aromatic nucleus ate as stable bodies as
the chlorobenzenes.
By treating any of the products thus obtained with chlorine and
iodine, further substitution takes place only iu the aromatic group ;
but by acting on the boiling compounds with pure chlorine, only the
hydrogen of the mothyl is replaced.
By means of these reactions the following substitution-products
have been obtained, to which are added some isomerides, which have
been formed by other reactions, and stand in the second or third line.
The numbers affixed to these compounds indicate the position of tho
chlorine (see page 314).