Enhanced activity of polymer-supported phase transfer catalysts

Abstract

Phase transfer catalysis has been a weapon in the arsenal of synthetic organic chemists for over three decades now. While phase transfer catalysts (PTCs) have found widespread use in the industry, the polymer-supported phase transfer catalysts, also known as triphase catalysts, have not gained industrial acceptance. Triphase catalysts offer many advantages associated with heterogeneous catalysts such as easy separation from the reaction mixture, reusability, and use in continuous reactors. These significant advantages notwithstanding, the main reason for the lack of interest in the industry for the use of triphase catalysts has been its reduced activity in comparison with soluble-phase transfer catalysts. Due to their heterogeneous nature, triphase catalysts, in general, have lower reactivity. In this paper, we address this issue of reduced activity of triphase catalysts for a specific reaction, that is, phase transfer esterification of benzyl chloride with aqueous sodium acetate. It has been found that the triphase catalyst has a higher reactivity than its soluble analogs. The kinetics of the phase transfer reaction using both soluble and polymer-supported catalysts has been determined and the results are presented.