A Manual of the Chemistry of the Carbon Compounds

THE CARBON COMPOUNDS. 226
ammonium salt of this aoid is produced by heating an aqueous solution
of aspatagin to 120°. To prepare the acid, asparagin is boiled with
baryta-water; ammonia is given off, and barium aspartate is formed,
which is decomposed by sulphuric acid, and the solution evaporated
to crystallization. It is a bibasic acid, forming crystalline salts.
When the acid silver salt is heated with ethyl iodide the ether
f CO OH
0 A(NHJH QO (Jog k formed, a crystalline solid, which by the
action of aqueous ammonia yields asparagin and ethyl alcohol.
FUMABIO ACID AND MALEIC ACID C4H404.
These two isomerio acids are obtained by heating malic acid :—
C4H006 =
Maleic acid distils over together with water, and is obtained in
crystals on evaporating the distillate. It forms large plates, and is
very soluble in water. It melts at about 130°, and when kept at that
temperature for some time it is transformed into fumaric acid, which
on stronger heating is decomposed into water and rnaleio anhydride
C4H%08, a compound which again combines with water, forming
maleic acid.
Ftnmrie Add occurs also in many plants (Corydalis, Futnaria,
and Glauoium species),
It is most conveniently obtained by exposing malic acid for some
time to a temperature of 120°—150°, It crystallizes in prisms and
is sparingly soluble in water, •
The two i8omeric acids combine with nascent hydrogen, both being
converted into snccinio acid. They also combine readily with bromine j
fumario acid yielding bibromosuccinic acid, from which it follows
that the constitution of fumaric acid is expressed by the following
formula:—
Fumario Acid, Bibromosuocinio Acid.
CH.CO.OH CHBr.CO.OH
IH.CO.OH CHBr.CO.OH
h
M&leio acid forma with bromine wMbromMUCtrinie add, the con-
CHa.CO.OH
stitution of which appears to be I , according to which
CBrj.00.OH
maleic acid would contain an atom of carbon with free combining
units.