ENANTIOSELECTIVE ESTERIFICATION OF 2-ARYLPROPIONIC ACIDS CATALYZED BYIMMOBILIZED RHIZOMUCOR-MIEHEI LIPASE

A systematic study of the enzymatic activity of immobilized lipase fro m Rhizomucor miehei (Lipozyme IM) in the enantioselective esterificati on of 2-arylpropionic acids has been carried out. The main variables c ontrolling the process (enzyme amount, water amount, temperature, stir ring speed, and type of organic solvent) were studied using factorial analysis. The negative effect of water amount is explained by means of water activity (a,) considerations. A new and easy to calculation par ameter (Enantiomeric Factor, EF) is defined for evaluating the enantio selectivity of the reaction. Influence of the alcohol and acid moietie s is also considered. Lipozyme IM shows S-(+) enantiorecognition in al l cases, except for (R,S)-Ketoprofen, where the R-(-) stereobias is co nfirmed using pure enantiomers (V-R/V-S = 8). An explanation for this different enantiopreference is suggested by means of MD calculus.