Kinetics and mechanism of synthesis of butyl isobutyrate over immobilised lipases

Abstract

Butyl isobutyrate is used mainly as a fixative and modifier in flavour industry. The present work focuses on the synthesis of butyl isobutyrate by esterification of isobutyric acid with n-butanol by using lipases. Effects of various parameters were studied to deduce the kinetics and mechanism of the reaction. Novozym SP 435 was found to be the most efficient catalyst and heptane was the best solvent. With equimolar quantities of the reactants in heptane, Novozym SP 435 offered a conversion of 56% at 30 °C in 6 h. Initial rate data and progress curve data were used to arrive at a suitable model. The initial rate studies showed that the Michaelis constant for n-butanol was very low indicating lower affinity between the enzyme and the reactant. The kinetics was found to obey the Ping-Pong bi-bi mechanism with n-butanol substrate inhibition.