Kinetics of phase-transfer catalyzed esterification of aliphatic dicarboxylate in solid-liquid system

The kinetics of synthesizing sebacic acid dibenzyl ester used as plasticizer or lubricant was investigated for the esterification of solid dipotassium sebacate with benzyl bromide via phase-transfer catalysis in a solid-liquid system. Without the addition of catalysts in a stirred batch reactor, no products were observed after 4 h at 80 degreesC. If one employs tetra-n-butylammonium bromide as the catalyst during this esterification of the aliphatic dicarboxylate, a product yield above 60% can be achieved for the same operating conditions. Factors affecting the efficiencies of the phase-transfer catalysts were explored to search for the reaction mechanism. A mechanism based on the concept of topochemical reaction in phase-transfer catalysis and homogeneous solubilization with a transition complex was proposed. The kinetic model was set up to describe the catalytic behaviors successfully for the overall reaction during and after the induction period. (C) 2001 Elsevier Science B.V. All rights reserved.