PROCESS FOR THE PRODUCTION OF HYDROXYARYLGLYOXYLIC ACIDS AND OF THE ALCALINE SALTS THEREOF, AND ITS APPLICATION TO THE PRODUCTION OF SODIUM PARA-HYDROXYPHENYLGLYOXYLATE

摘要

Process for producing hydroxyarylglycoxylic acids from hydroxyarylglycolic acids by catalytic oxidation in an alkaline aqueous medium, at a pH higher or equal to 11.5 by oxygen or by oxygen-containing gas, characterized in that it is carried out in homogeneous phase at a temperature lower or equal to 30 C and in the presence of cupric ions and in that at the end of the reaction the acid looked for is isolated from the reaction medium by acidification at a pH of about 0.5. The sodium para-hydroxyphenilglyoxylate is obtained at the end of the reaction when the acidification is stopped at a pH of 5.