Reagents on styrene-divinylbenzene supports with improved accessibility

Abstract

Macroporous styrene-divinylbenzene copolymers have been prepared using a solution of polystyrene in toluene as a porogenic diluent. Pore volume and pore size distribution are critically dependent on both the amount and the concentration of the diluent solution. Attempts to graft first a radical azo generator and then to use it for grafting a functional polymer are described but were not fully successful. A second approach was the post-polymerization of vinylbenzyl chloride through the residual double bonds of the initial resin, after swelling in a concentrated solution of the monomer. The chloromethylated porous resin was further derivatized to a sulfoxide containing one. A two-step process was employed involving first a phase transfer sulfuration and then an oxidation. The first reaction was limited to an extent depending mostly on the initial chlorine content of the resin. The final product was used as a catalyst for the alkylation of benzyl cyanide with butyl bromide. The catalytic activity, although lower than that of a soluble copolymer of the same composition as the graft, was definitely higher in terms of rate and upper limit than that of conventional macroporous or gel-type catalysts.