METHOD FOR PRODUCING GLYCOLIC ACID

摘要

PURPOSE:To provide the method for directly producing the free glycolic acid from glyoxal as a starting substance in a high yield by a simple method. CONSTITUTION:The aqueous solution of glyoxal, is heated at >=50 deg.C, especially 100-200 deg.C, in the presence of a Bronsted's acid to produce the glycolic acid. The concentration of the glyoxal is <=85wt.%, preferably 5-60wt.%, especially 10-40wt.%. An inorganic acid, an organic acid, an organic sulfonic acid, an acidic ion exchange resin, etc., particularly the organic carboxylic acid, especially the glycolic acid of reaction product is preferably used as the Bronsted's acid. The Bronsted's acid is used in an amount of >=0.5 equivalent, especially 0.00001-0.05 equivalent, per mole number of the glyoxal. The glycolic acid produced by the reaction may be used as the glycolic acid aqueous solution as such, but may, if necessary, be taken out as the glycolic acid aqueous solution through conventional operations such as a concentration operation and a purification operation.