A Manual of the Chemistry of the Carbon Compounds

146 TEE CHEMISTRY OF
Chloral or Trichloracetaldeli-yde GjClgOH is obtained by passing dry
chlorine into absolute alcohol as long as any action takes place.
The final product, however, is not chloral, but a Bolid compound of
chloral and alcohol called chloral alcokolate, which is decomposed by
concentrated sulphuric acid into alcohol and chloral:—
CClj.COH + C^OH
The reaction by which chloral alcoholate is produced is rather complicated.
Erst aldehyde is formed, which combines with some of the
alcohol, forming aeetal CH8.CH(00oHB)2, a compound which will be
described under ethidene compounds. By the action of chlorine on
aeetal, it is next converted into trichloracetal, which by the hydrochloric
acid produced is resolved into chloral alcoholate and ethyl
chloride:—
HC1 = CC1S.CH {
Chloral is also formed by the action of chlorine upon aldehyde; it
is a colourless liquid, possessing a peculiar irritating smell, and boiling
at 99°. Like common aldehyde, it reduces silver from an ammoniacal
solution of the nitrate, and forms crystalline compounds with
ammonia and the acid sulphites of the alkali-metals. Hydrogen
in the nascent state converts it into aldehyde, and oxidizing agents
transform it into trichloracetic acid. It combines with water, with,
the evolution of heat, forming Mwal hydrate C01j.CH(OH)g, white
transparent monocline crystals boiling afc 120°; concentrated sulphuric
acid again resolves this body into water and chloral. Chloral
also combines with alcohols, with acetamida and other amides, and
with urea. By the action of aqueous alkalis it splits up into chloroform
and formic acid ;—
COVCOH + KOH « CC1,H + COH.OK
Chloral undergoes polymerization on standing for some time, metackloral
being formed, a white porcelain-like nvasa; this change takes
place much quicker in presence of a little sulphurio acid. On heating
metaehloral to 180° it is again transformed into chloral.
Chloral hydrate is used as a very valuable medicine; it acts as a
sedative and antispasmodic, producing ansesthesia and a quiet sleep.
By adding a little water to a mixture of chloral hydrate and potassium
cyanide, and heating gently, a violent reaction ensues; torrents
of hydrocyanic acid escape and diohloracetic acid is formed :—
CCl,.CH(OH), 4- KGN = CHCla.CO.OH + HCN + KOI
Monobromaeetu Add l r> JJ !• 0 is obtained by heating together
bromine and acetic acid in sealed tubes to 150°. It forms colourless