PRODUCTION OF HYDROXYPHENYLACETIC ACID

摘要

PURPOSE:hydroxymandelic acid, which is readily obtained from phenol and glyoxylic acid, is used to effect catalytic hydrogenation in an aqueous medium at a specific pH to produce the titled compound used as an intermediate of medicines or agricultural chemicals in high yield with no use of a large amount of hydrochloric acid without corrosion of the facilities. CONSTITUTION:The catalytic hydrogenation of hydroxymandelic acid is carried out in an aqueous medium at a pH of 3-5 at a temperature of 100-200 deg.C, preferably 160-180 deg.C and a pressure of higher than 10kg/cm<2>G, preferably higher than 13kg/cm<2>G in the presence of a catalyst of palladium such as palladium on carbon to give the titled compound. The hydroxymandelic acid is obtained by reaction of phenol with glyoxylic acid in the presence of an alkali in an aqueous medium and can be used directly in the following hydrogenation without isolation. The amount of the aqueous medium is used so that the concentration of the hydroxymandelic acid becomes 6-20wt%.