Full model for reversible kinetics of lipase-catalyzed sugar-ester synthesis in 2-methyl 2-butanol

A kinetic model derived from the ping-pong bi-bi reversible mechanism is proposed to described the acylation of glucose by lauric acid in 2-methyl 2-butanol mediated by Candida antarctica lipase at 60degreesC. The model accounts for the effect of all four compounds in the reaction mixture, namely lauric acid, glucose, water, and lauroyl glucose ester. A supersaturated glucose solution was used to avoid limitations by glucose dissolution rate. Experiments with varied initial water content were performed to determine the effect of water on the initial reaction rate. The full time course of ester formation is described by five parameters: (a) three parameters evaluated from initial rate measurements; (b) the equilibrium constant, independently evaluated; and (c) one extra parameter fitted to the progress curve of ester formation. This reduced form of a full reversible kinetic model based on the ping-pong bi-bi mechanism is able to describe the complete course of lauroyl glucose ester synthesis. The proposed model provides a good fit for the experimental results. (C) 2002 Wiley Periodicals, Inc.