Baeyer–Villiger Oxidation of Cyclohexanone in Aqueous Medium with In Situ Generation of Peracid Catalyzed by Perhydrolase CLEA

Abstract

A perhydrolase, immobilized as a cross linked enzyme aggregate (CLEA), was employed to catalyze the in situ formation of peracetic acid (PAA) from ethylene glycol diacetate (EGDA) and hydrogen peroxide. The produced PAA was used for the Baeyer–Villiger oxidation of cyclohexanone, which afforded caprolactone in 63 % yield. The effect of type and amount of acyl donor, solvent, pH, temperature and ratio of cyclohexanone to hydrogen peroxide on the production of caprolactone was studied. The highest caprolactone yield was obtained with 100 mM EGDA as the acyl donor at pH 6 and room temperature using a ratio of cyclohexanone to hydrogen peroxide ratio of 1:4. Interestingly, the perhydrolase CLEA exhibited the highest activity in aqueous medium in contrast to the well studied lipase B from Candida antarctica. The perhydrolase CLEA proved to be a very efficient catalyst; the K m and Vmax values were 118 mM and 56.3 μmol min−1, respectively.