Synthesis of glyoxalic acid from glyoxal

A chemo-enzymic route was devised for the synthesis of glyoxalic acid from glyoxal. Glyoxal was converted chemically to glycolic acid, which was oxidised to glyoxalic acid with a glycolate oxidase from spinach. The two steps were studied independently as well as singly. The conversion of glyoxal to glycolic acid was 95% at a mol ratio of 1:1.5, giving 98% selectivity towards glycolic acid at 25 degrees C. The chemical route involves the hydrolysis of glyoxal with NaOH as catalyst with a second-order rate constant 9.3 x 10(-6) cm(3)/mol ger s at 25 degrees C. The effect of different parameters was studied on conversion and selectivity for the enzymic reaction. Conversion increased with reaction time but selectivity decreased. The formation of by-production due to further oxidation to oxalic acid and formic acid can be suppressed by using catalase at a concentration of 2000 U/ml. The enzymic conversion of glycolic acid to glyoxalic acid resulted in 24% conversion with 86% selectivity, after a reaction period of 90 min at 25 degrees C with air sparging. The chemo-enzymic route overall led to a 20% yield of glyoxalic acid from glyoxal in 90 min. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.