PURPOSE: In producing pyruvic acid by hydrolyzing methyl pyruvate, to obtain advantageously the aimed compound in high purity, by carrying out the reaction at a specific temperature and at a specific conversion of raw material, distilling away an unreacted raw material as an azeotropic mixture with water.
CONSTITUTION: Methyl pyruvate is hydrolyzed in the presence of water and an acid catalyst at 50W80°C, preferably at 60W75°C while limiting conversion of raw material to ≤98%, preferably 50W97%, especially 80W95%, and an unreacted raw material is distilled away as an azeotropic mixture with water from the reaction mixture, to obtain industrially advantageously high-purity pyruvic acid from an easily obtainable raw material. Pyruvic acid is preferably as the catalyst, the reaction is carried out in a distillation column, formed methanol is successively distilled away to suppress side reactions, and at least part of the reaction mixture existing in the bottom of the column is preferably circulated through the middle plate of the column so that contact efficiency of the raw material and the catalyst (pyruvic acid) is raised.
OSAKI TAKAYOSHI
YOSHIMURA NORIAKI
YAMADA OSAMU
TANI SHIGEKI
