A Manual of the Chemistry of the Carbon Compounds

364 THE CHEMISTRY OF
a Dichlorobenzoic, or JHcMorodtatylie Add CLHgCLCOgH, has been
obtained by several reactions. It is formed by oxidizing dichlorotoluene
with chromic acid, aad by beating dieklorctommyl trichloride
CeHgClj.CCl;, (aee page 346) -with water to 100°. The same acid is
produced by heating chlorodraoylic acid with antimony pentaohloride,
and by boiling benzoic acid with a clear solution of bleaching-powder,
precipitating with hydrochloric acid, and boiling the precipitate again
•with bleaching-powder;—-
It crystallizes in slender needles, melting at 202°.
£ JHchlorobmzoic, or DuMorosalylic Add, has been obtained by
heating ohlorosalylio acid with antimony pentachloride. It crystallizes
in glistening needles, melting at 148°,
1-3 Bromobenaric Add C,1H4Br.CO2H is obtained when benzoic acid
is heated with bromine and water to 100°. It crystallizes in needles,
melting at 154°,
14 Brwndbenzoic Add is produced by oxidizing parabromotoluene,
and forms needles, melting at 251°.
1*2 Bromobmuric Add has been obtained from the corresponding
amtdobenzoic acid by converting it into a diazo-compound, and decomposing
this by hydrobtomic acid. It sublimes in flat needles,
melting at 138°,
We know, also, the three vxlohnzvic adds which hare been produced
from the corresponding diazo-compounds.
Ftuobenzoie Add C^H4F,CO.H is produced hy acting with fuming
hydrofluoric acid on diazo-amidobenzoio acid. It crystallizes from an
aqueous solution in large rhombic prisms, melting at 182°. It volatilizes
with the vapour of water, and forms crystalline salts.
1-3 Ortlimitrobetwui Acid GJB.t(W£COJl.—To prepare this acid
an intimate mixture of one part of benzoic acid and two parts of
nitre is added, to three parts of sulphuric acid, and then gently heated
until the nitro-acid swims as an oily layer on the top. To remove some
metanitrobenzoic aoid, which forms at the same time, the product is
three times exhausted with about twice its quantity of boiling water,
and the residue either crystallized from more boiling water, or sublimed.
The pure acid forms colourless needles, melting at 140°. It is
also obtaiued by oxidizing orfchonitrotoluerw.
1-2 Metanitrobenzoic Acid is formed, but only in small quantity,
together with the ortho-acid. The aoid, as well as its salts, are much
more soluble than their isomerides, and distinguished by their intensely
sweet taste, while most other nitro-compounds have a bitter
taste. The aoid crystallizes by the slow evaporation of an alcoholic
solution in large yellowish prisms, melting at 146*,