Enzymatically catalysed transesterifications of acryl and methacryl monomeric esters

A highly stabilized, immobilized pig liver esterase was found effective in catalysing both hydrolysis and transesterification reactions of methyl and ethyl esters of acrylic and methacrylic acids. The enzyme was successfully employed for the preparation of hydroxy- and dihydroxyalkyl acrylates and methacrylates, without di- or triacrylate and methacrylate formation. Employing high substituting alcohol concentrations (e.g. 50-70%, v/v), competing hydrolysis could be minimized. The effective prestabilization of the enzyme made possible the measurement of kinetic parameters across the whole range of alcohol-water mixtures. The enzyme exhibited the usual kinetic behavior under these conditions. Substrate and product inhibitions were recorded for the PLE-catalysed transesterification of these monomeric esters, accompanied by somewhat narrow specificity to the substituting alcohol. Thus, 2-hydroxyethyl, 2-hydroxypropyl, and 1,2 dihydroxypropyl esters of acrylic and methacrylic acids could be prepared without di- or triester formation. The results indicate that the spectrum of potential products based on this approach may be extended by employing other esterases in a similar way.