A Manual of the Chemistry of the Carbon Compounds

26B THE CHEMISTRY OF
as always those two carbon atoms are torn asunder which are linked
together by two of the combining units of each.
Acrylaldehyde or Anrolein CgHjO is easily obtained by depriving
glycerin of the elements of water :—
CgH8O8-2^0 = 0,11,0
This is best effected by heating glycerin with acid potassium sulphate
or phosphorus pentoxide. It is a colourless liquid boiling at
52 O> 4. Its vapour is most irritating, attacking most violently the
unicous membranes of the nose and eyes. It is the cause of the
intolerable odour given off by fats and glycerin when subjected to
destructive distillation. It is a very unstable body; in closed vessels
it soon changes into a white flocculent substance or a resinous mass,
called disaeryl or disacryl-rcsin. When acrolein is heated with alcohol
and acetic acid, it is converted iuto triethylhydrin;—
CH3
GHrOGA
C + 3C2H6.OH = CH.OC2H6
CH3
CH2.OC2H6
Wlwn ammonia is passed into an ethereal solution of acrolein a
white amorphous powder called acrolcin-ammonia (C8H4O)8NH8 is
precipitated.
It also combines with hydrochloric acid, forming a crystalline
compound C8H4O.HC1, which on distillation with an alkali is converted
into a polymeride of acrolein called metacrolcin, forming
beautiful crystals, which by the action of heat or acids are reconverted
into acrolein.
Acrolein hydrochloride yields, by the action of hydrochloric aoid,
triolilorhydrin and water. When acroleiu is treated with phospho*
rua pentacliloride two isomerides are formed, one being dichlwoglycide
and the second has been called aerol dichloride C8H4Clr mscent
hydrogen converts aorolein into allyl aloohol.
Acrylic Acid C,H4O2 is produced by adding silver oxide to an
aqueous solution or acrolein and allowing the mixture to stand for a
few days;—
2C3H40 + 3Ag8O = 2C8H3Ag08 + H,0 + 4Ag
The acid is not formed by the direct oxidation of tlie alcohol, the
latter being nearly completely destroyed 5 but it has been produced
by combining allyl alconol with bromine, oxidizing the bibroroopro*
pyl alcohol with nitric acid, and heatjDg the bibromopropionic acid
with zinc dusfc and water;—