Ion-exchange resin catalysis in the synthesis of isopropyl lactate

Abstract

Isopropyl lactate is a very important pharmaceutical intermediate. The current practice is to use homogeneous acids as catalysts. These catalysts are hazardous and disposal of liquid acid effluents poses problems. The separation of the liquid catalyst and its reuse is another problem. The current paper deals with the application of heterogeneous catalysts Indion-130, Ambelyst-36, Amberlyst-15, Amberlite-120, Dowex 50W, Filtrol-44, 20% DTPA/K-10 (dodecatungstophosphoric acid supported on K-10 clay) and 20% DTPA/Filtrol-44 (dodecatungstophosphoric acid supported on Filtrol-44 clay). Amongst these Amberlyst-36, Amberlyst-15 and Indion-130 were observed to be most effective. A theoretical kinetic model was developed for evaluation of this slurry reaction. The effects of various parameters on the rate of reaction were evaluated. The reaction was found to be intrinsically kinetically controlled and there were no intraparticle as well as interparticle mass transfer limitations on the rate of reaction.