A Manual of the Chemistry of the Carbon Compounds

830 THE CUBMT8TRY OF
ganic substance of very simple constitution to a complex organic
acid. This is a point of great interest, because glycollates and- tartratea
occur together in grapes and the leaves of the wild vine,
The salts of inactive tartaric acid have a great resemblance to the
raoemates.
The different modifications of tartario aoid can be transformed
into each other. Thus by combining either of the two active acids
with cinchooine and heating the salts to 170", a resinous mass is
formed containing a large quantity of cinchonine racemate, and tliis
salt when heated for a long time is converted into the salt of the
inactive acid. When dextrotartaric acid is heated with a little water
in sealed tubes to 165° a small quantity of raceme acid is formed,
together with a large quantity of the inactive acid, whilst when the
temperature is raised to 175° chiefly racemic acid is formed. By
means of this reaction inactive acid obtained synthetically from
ethene has been transformed into racemic acid, which is identical
with that contained in grapes, and could be resolved into the two
active modifications. This is the first example of the complete
synthesis of a body turning the plane of polarization. 1
When any of the four modifications of tartaric acid is subjected to
destructive distillation it gives off water and carbon dioxide, and three
new acids are formed:—
Pyroracomic AcM.
= C3H4O$ + CO2 + Ha0
Pyrotarturic Acid.
- C6H8O4 +
Pyrotritarie Acid.
3C«H6Oa = C7H8O, +
Pytoracenio or Pyntvic Acid C8H,O8 is a colourless liquid possessing
a puugeut smell like acetio acid, and boiling at 16*5°. It combines
with nascent hydrogen, and is transformed into lactic acid, to
which it stands in the same relation as dimethyl ketone to secondary
propyl alcohol :—
CH8 CH8
I 1
CO + H8 = CH.OH
I I
CO.OH CO.OH
On boiling pyruvic acid or a pyruvate with water it changes into a
non-volatile syrupy modification, which forms amorphous salts. On
heating this substance, which is probably a polymeride of the volatile
acid, it is resolved into carbon dioxide and pyrofcarfcaric acid:—
• On page 43 it is said " that no carbon compound prepared by synthesis has bean
found to lie o]*ioally native," the above reactiou not Doing known ut the time whou
this was printed.