Recyclable Heterogeneous Radical Generators Toward In-Flow Polymer Elaboration System

Abstract

Radical reaction is one of the most common industrial reactions for the production of materials used in a wide variety of applications. Despite its long history, a methodology enabling efficient radical reactions with safe and easy handling still remains a challenge. Here, we describe the synthesis of crosslinked copolymers containing 2,4,5-triphenylimidazoles (lophines) and hexaarylbiimidazoles (HABIs) (CCs) and fabrication of silica-supported CCs (s-CCs). Both of lophines and HABIs in these materials generated 2,4,5-triphenylimidazolyl radicals (TPIRs) upon oxidation and photoirradiation, respectively, and thus they act as heterogeneous radical generators (HRGs). Moreover, lophine and TPIR were interconvertible via oxidation and hydrogen atom transfer reaction, enabling marked recyclability of these materials. We have further packed s-CCs in columns and realized in-flow disulfide synthesis and radical polymerization.