Experimental optimization of enzymic kinetic resolution of racemic flurbiprofen.

Immobilized lipase from Candida antarctica (Novozym 435) was employed for the kinetic resolution of racemic flurbiprofen by the method of enantioselective esterification with alcohols. However, the presence of accumulated water from the esterification influenced the enantiomeric ratio and reaction rate, due to increased rate of hydrolysis of the esterified enantiomer. In the present study, the procedure for optimizing the experimental resolution of the racemate was tested, with a focus on solvent and alcohol types, inhibition of alcohol substrates and the nature of the reversible reaction. The optimal concentration of feed flurbiprofen (180 mM or 44 mg/ml) was determined on basis of the maximum water content favourable for esterification, in single resolution, with the use of methanol in the solvent of cyclohexane.