Lipase catalysed transesterification of 2-o-benzylglycerol with vinyl acetate: solvent effect

The Pseudomonas cepacia lipase catalysed synthesis of (S)-2-o-benzylglycerol-1-acetate by transesterification of 2-o-benzylglycerol with vinyl acetate was studied in 10 different solvents in order to deduce the solvent effect through an attempt to correlate the initial reaction rate, selectivity for monoester formation and enantiomeric excess (ee) with such solvent properties as hydrophobicity (logP), water solubility (logSw), electron pair acceptance (ETN) and donation abilities (DNN), polarisability and dielectric constant. The initial rate was found to exhibit reasonable correlation with logP, logSw, ETN+DNN, logP/polarisability and dielectric constant. The correlations for selectivity and ee were also found to be reasonable excepting deviation of data points of certain solvents. Probable explanation for the deviation has been put forwarded based on established hypothesis. The study revealed, in general that polar solvents favour the initial reaction rate, selectivity and enantiomeric excess for transesterification of prochiral diol to chiral monoester.