Immobilized lipase-catalysed esterification and transesterification reactions in non-aqueous media for the synthesis of tetrahydrofurfuryl butyrate: comparison and kinetic modeling

Abstract

Immobilized lipase-catalyzed synthesis of tetrahydrofurfuryl butyrate is reported in this paper. Esterification and transesterification of tetrahydrofurfuryl alcohol (THFA) with butyric acid (BA) and transesterification with ethyl butyrate (EB) to prepare tetrahydrofurfuryl butyrate (THFB) were studied systematically including kinetic modeling. A series of immobilized lipases such as Novozym 435, Lipozyme IM 20, Pseudomonas species lipase on toyonite (PSL/Toyo), Candida rugosa lipase (CRL) on polypropylene, CRL on egg shells and CRL on celite were screened to establish that Novozym 435 was the best catalyst for both esterification and transesterification at 30°C. The effects of various parameters on reaction rates were studied in detail for both reactions with Novozym 435. The ping-pong bi–bi mechanism with inhibition by the substrate THFA fits the data for esterification whereas the ping-pong bi–bi mechanism with inhibition by both the reactants (THFA and EB) and both the products (THFB and ethanol) is valid for the transesterification reaction. The kinetic parameters deduced from these models were used to simulate the conversions, which are in good agreement with the experimental values. Since transesterification suffers inhibition by both the substrates and products, esterification is a better method compared to transesterification.