The hydrolytic resolution of (R,S)-2,2,2-trifluoroethyl α-chlorophenylacetate in water-saturated isooctane containing Lipase MY(I) at 35• C is selected as the best reaction condition for producing (R)-α-chlorophenyl acetic acid. The kinetic constants, and hence an enantiomeric ratio of 33.6, are estimated and employed for the modeling of time-course conversions of both substrates by considering product inhibition and enzyme deactivation effects. A successful dynamic kinetic resolution is also achieved, giving the desired (R)-α-chlorophenylacetic acid of 93.0% yield and ee P = 89.5% when 80 mmol dm −3 trioctylamine acting as the racemization catalyst and enzyme activator is initially added.

By using strong neutral bases as catalyst, a detailed investigation of the racemization of (S)‐naproxen 2,2,2‐trifluoroethyl ester was conducted in the non‐polar solvents isooctane, cyclohexane and n‐hexane. The second‐order interconversion constant $k^*_{\rm int}$ as representing the ion‐pair kinetic basicity in isooctane was first estimated and correlated with the equilibrium ion‐pair basicity pKip in tetrahydrofuran, giving slopes of 0.768 and 0.689 for non‐phosphazene and phosphazene bases, respectively, in the Brønsted correlations. The result was further compared with that for (S)‐naproxen 2,2,2‐trifluoroethyl thioester, showing about a 1–2 orders of magnitude enhancement of $k^*_{\rm int}$ for the corresponding thio‐containing analogue. A smaller influence of non‐polar solvents (i.e. isooctane, n‐hexane and cyclohexane) on $k^*_{\rm int}$ was found. Kinetic analysis of the racemization and hydrolysis of (S)‐naproxen 2,2,2‐trifluoroethyl ester in isooctane and n‐hexane containing 7‐methyl‐1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene and water suggests nucleophilic hydrolysis by the base, where the breakdown of tetrahedral intermediates IR1 and IS1 is the rate‐limiting step and the hydrolysis constant khy is in proportion to the product of base and ion‐pair concentrations. Copyright © 2004 John Wiley & Sons, Ltd.