A Manual of the Chemistry of the Carbon Compounds

332 TEE CHEMISTRY OF
Phenol lias been obtained synthetically by dissolving acetylene in
fuming sulphuric acid, and fusing the sulpho-ncid thus formed with
caustic potash;—
SCaH-SOaK + 3K0H = C6HO.OH + 2K2SO4 + K ^
Phenol is manufactured on the large scale by agitating heavy coaltar
oiJ, boiling above 160°, with a concentrated soda-solution, to which
some solid caustic soda is added. A crystalline magma is formed,
whilst neutral oils are left undissolved. After the latter have been
separated, the soda-compound is decomposed with hydrochloric acid,
and the impure phenol again treated with a quantity of soda, which
is insufficient to dissolve the whole; phenol dissolving iu alkalis
mote readily than cresol and other homologues, which are present in the
crude product. The solution is exposed to the air, in order to remove
impurities which are easily oxidized, and soon separate as a tarry
matter. The clear liquid is then treated with hydrochloric acid, and
the phenol, after being dried over calcium chloride, is submitted to
fractional distillation. From the portion boiling below 190°, phenol
separates out in crystals on cooling.
Pure phenol may also be obtained by heating salicylic acid (oxybenzoic
acid) with quicklime; this reaction is quite analogous to the
formation of benzene from benzoic acid:—
Pure phenol crystallizes in long, colourless needles, melting at 42°,
and boiling at 184°, It possesses a characteristic odour and a
pungent and caustic taste, producing white blisters on the tongue. It
combines with water, forming a crystallized hydrate 2(C6H5.0H)+H8O,
which by distillation is again resolved into water and phenol.
Pure phenol remains unaltered in tho air, but the commercial product
soon absorbs water, and is converted into a red liquid. It is
rauoh used as a disinfectant, and for the conservation of wood, because
it possesses the property of preventing putrefaction.
Ferric chloride produces in an aqueous solution of phenol a violet
colour; and, with a little ammonia and a solution of bleachingpowder,
it yields a fine blue colour. The best reagent for phenol is,
however, bromine-water (see tribromopheuol),
Mcthyl-plicnyl Ether, or Anisol nlr 5 f 0.—This compound was first
obtained by distilling anisic acid with baryta, and is easily prepared
by heating potassium phenate with methyl iodide. It is a coloruless
liquid, possessing an aromatic odour, and boiling at 152°, By heating
it with hydriodic acid to 130°, it is resolved into methyl iodide and
phenol.
Mhyl-phenyl Ether, or Phtmetol CgHyO.CjH^ is obtained hi a similar
way from ethyl iodide; it is an aromatic liquid, boiling at. 172°.