A Manual of the Chemistry of the Carbon Compounds

212 TRB CHEMISTRY OF
This etherification also takes place slowly, -when an aqueous solution
of laotic acid is allowed to remain over sulphuric in vacuo, and
for this reason pure anhydrous lactic acid is not obtainable.
The anhydride is very slowly decomposed by water alone, but
quickly in presence of alkalis, into two molecules of lactic acid.
Lactide CgH4O3.—When the so-called anhydride is heated to 210°,
lactide, or the real lactio anhydride, is formed. It crystallizes from
alcohol in shining rhombic plates, and is sparingly soluble in water,
with which it slowly combines, to form lactic acid, When quickly
heated it splits up into carbon monoxide and aldehyde;—
CH,
CH8
+ C0
a
> ~ ^
HO
AMIDES OF LAOTIC AOID.
Lactamide CaH1(0H)C0NH2 is formed by the combination of
lactide with dry ammonia:—
CH8 C
G
CH8
- NH3 = CH.OH
CO.NH8
The same compound is produced by heating ethyl lactate with
ammonia; it is freely soluble in water, and orystallizes in plates,
melting at 74°. When it is heated with potash-solution, ammonia
is evolved and potassium lactate is formed.
Alanine or Amidopropionie Acid CaH.(NHa)CO8H."—This compound
is obtained by heating ethyl a cnloropropiouate with ammonia,
or by boiling two parts of aldehyde-ammonia and one pact of
anhydrous prussio acid with an excess of dilute hydrochloric acid;—•
CH3 CH3
CHNH,, + CNH + § 10 + HC1 = OHNHS + NH4G1
OH CO.OH
On evaporating the solution a mixture of sal-ammoniac and alanine
liydrochloride crystallizes out. The latter is dissolved in absolute
alcohol, and the solution treated with lead hydroxide, lead chloride
being formed and lead amidoprojrionate, which is decomposed with
hydrogen sulphide. Altmine crystallizes from an alcoholic solution