Synthesis and Solid-State ¹³C NMR Study of Polymer-Bound Triphenylmethyl Cations

Abstract

A polymer-bound cation system of the triphenylmethyl type has been synthesized via a method in which the first step is lithiation of polystyrene. The final step in the synthesis of the polystyrene-bound triphenylmethyl carbocation system was either conversion of the corresponding polymer-bound triphenylmethyl chloride with AlCl3 or the conversion of the polymer-bound triphenylmethyl alcohol with perchloric acid. The various functionalized polymer samples were characterized by solid-state 13C NMR, which showed that, for the polymer-bound triphenylmethyl alcohol system, there are 0.59 mmol of carbinol moieties per gram of polymer. The polymer-bound carbocation system was found to be surprisingly stable, even to moisture in air, and can readily be regenerated from its hydrolysis product. The polymer-bound carbocation system is effective as a catalyst in a Michael addition reaction and as a hydride acceptor reagent in a Dauben-type hydride transfer reaction.