A chemo-enzymic route was devised for the synthesis of glyoxalic acid from
glyoxal. Glyoxal was converted chemically to glycolic acid, which was oxidi
sed 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 towar
ds glycolic acid at 25 degrees C. The chemical route involves the hydrolysi
s 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. Convers
ion increased with reaction time but selectivity decreased. The formation o
f 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 enzym
ic 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 wi
th air sparging. The chemo-enzymic route overall led to a 20% yield of glyo
xalic acid from glyoxal in 90 min. (C) 2000 Published by Elsevier Science L
td. All rights reserved.