Preparation of polyethers with viologen moieties and their application to the debromination of diphenyl bromomethane

Abstract

Polyethers with viologen moieties were prepared by the reaction of iodinated poly(ethylene glycol) (PEG) with 4,4′-bipyridine. These polymers were used as electron-transfer catalysts (ETC) for the reduction of diphenyl bromomethane (Ph 2CHBr). Results disclosed that these polymers could induce the debromination of Ph 2CHBr to afford tetraphenyl ethane effectively. An EPR method proved that the reduced viologen cation radical in a PEG chain was more stable, and an active intermediate was detected by employing the spin-trapping agent (POBN). This showed that the debromination of Ph 2CHBr proceeded via a radical mechanism.