| The resolution of mandelic acid was studied in ionic liquids including [Bmim][Br],[Bmim][PF6],[Bmim][BF4],[Omim][PF6],via enzyme-catalyzed hydrolysis of racemic ethyl mandelate. Novozym 435, CRL,Pepsin and Lipozyme TL IM were screened for their enantioselectivity and activity to get enantiopure mandelic acid. It has been found that Novozym 435 exhibited excellent enantioselectivity and activity in the system containing the IL [Bmim][Br] compared to several other ILs tested. Effects of various parameters such as ionic liquid concentration, substrate concentration, reaction time, reaction temperature, pH and shaking rate were studied. The optimum substrate concentration, ionic liquid concentration, pH, enzyme loading, reaction temperature, shaking rate and reaction time were 0.35 mol/L, 1.71 mol/L [BMIM]Br, pH 7.5, 10 mg N435, 30 oC, 150 r/min ,and 6 h, respectively, under which the enantiomeric excess(ee) and yield of production could reach 58.78% and 65.23%, respectively. The ionic liquid [BMIM]Br was synthetized by ourselves and reused by purifying with ethyl acetate.The reaction rate could be described in terms of the Michaelis-Menten equation with the inhibition by substrate and product. Considering the effect of ionic liquid on enzyme, the kinetic model which follows quasi-steady state was built. The kinetic equation was : Model results were found to fit the initial rate data very well.
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