Etherification of halo-ester by phase-transfer catalysis in solid-liquid system

In the present study, the kinetics for the etherification of ethyl 2-bromoisobutyrate with potassium 4-benzyloxyphenoxide in the presence of potassium iodide via solid-liquid phase-transfer catalysis (SLPTC) was investigated. The reaction was carried out in a stirred batch reactor. The effects of agitation speeds, concentration of reactants, phase-transfer catalysts, organic solvents, amounts of catalysts, and reaction temperatures were performed to find the appropriate conditions. Using the present reaction system, the hydrolysis side reaction of ether-ester was prevented. A kinetic model taking into account the deactivation behavior of the catalyst was proposed to describe the overall reaction successfully. The pseudo first-order kinetics with the deactivation function was employed to estimate the initial apparent rate constants and the deactivation constants empirically. The activation energies for catalysts tetra-n-butylammonium bromide and tetra-n-phosphonium bromide as well as the behavior of co-catalyst potassium iodide in solid-liquid phase-transfer catalysis were obtained. (C) 2000 Elsevier Science B.V. All rights reserved.