Organic Syntheses, Coll. Vol. 1, p.475 (1941); Vol. 4, p.63 (1925).
An intimate mixture of 600 g. (4.4 moles) of finely powdered, freshly fused potassium acid sulfate
and 400 g. (2.7 moles) of powdered tartaric acid
, prepared by grinding them together in a mortar
, is placed in a 3-l. round-bottomed Pyrex flask
connected with a condenser
which is filled with water but does not have any water flowing through it. The mixture is heated by means of an oil bath
maintained at a temperature between 210 and 220° until liquid no longer distils over. Some foaming takes place (Note 1)
, but, if fused potassium acid sulfate
is used and the temperature of the bath does not rise above 220°, it is not difficult to control. The distillate is then fractionated under reduced pressure. Pyruvic acid
passes over at 75–80°/25 mm.
and the yield is 117–128 g.
per cent of the theoretical amount) (Note 2)
If the mixture foams badly, it may be kept from frothing over by heating the upper part of the flask with a free flame.
The cake left in the reaction flask may be removed readily by inverting over a steam jet
can be prepared by the hydrolysis of α,α-dichloropropionic acid
, 2 α,α-dibromopropionic acid
,2 acetyl cyanide
and oxal-acetic ester
and by the distillation of tartaric acid
or glyceric acid
Better results are obtained, however, by the distillation of tartaric acid
in the presence of a dehydrating agent such as potassium bisulfate
and the procedure described was adopted after a study of a variety of dehydrating agents and various experimental conditions. The ethyl ester
can be prepared by the catalytic oxidation of ethyl lactate
and the acid has been obtained by the oxidation of methylglyoxal bisulfite
This preparation is referenced from:
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