The effect of ethanol on the kinetics of lipase-mediated enantioselective esterification of 4-methyloctanoic acid and the hydrolysis of its ethyl ester

The Novozym 435(R) catalyzed esterification and hydrolysis reactions of 4-m ethyloctanoic acid (ethyl ester) were investigated. In both the hydrolysis and esterification reactions, the increase of ethanol concentration led to an increase in enantiomeric ratio (E). For hydrolysis of the ethyl ester, t he E-value increased from 5.5 [0% (v/v) EtOH] up to 12 [20% (v/v) EtOH]. In case of esterification, the E-value was already 16 [14% (v/v) EtOH] and ro se to 57 [73% (v/v) EtOH]. When combining these results of esterification a nd hydrolysis, an enantiomeric ratio of 350 can be estimated for the sequen tial kinetic resolution of 4-methyloctanoic acid. In this way, enantiopure 4-methyloctanoic acid could be obtained after two consecutive reaction step s. (C) 2001 John Wiley & Sons, Inc.