Functionalized Electron‐Rich Pyridines as Initiators for the Epoxy Homopolymerization

Abstract

AbstractA simple and modular dialkylation of two electron‐rich pyridine derivatives, namely 4‐aminopyridine or 1,2,3,4‐tetrahydropyrido[3,4‐b]pyrazine, is achieved by aza‐Michael reactions with electron‐poor olefins (ethyl acrylate and acrylonitrile). Reducing the ester groups in the ethyl acrylate‐derived compounds yielded the corresponding hydroxyl‐containing derivatives. Subsequently, homopolymerization of phenyl glycidyl ether as well as an epoxy‐alcohol polyaddition are catalyzed using the introduced compounds. As a reference catalyst, 4‐dimethylaminopyridine is used. It is found that in all cases an irreversible termination of the polymerization at temperatures above 100 °C occurred. The decomposition is particularly rapid in the case of pyridine derivatives containing hydroxyl groups. In contrast, at a constant temperature of 100 °C, the latter compounds gave the fastest phenyl glycidyl ether homopolymerization and high conversions are found for all electron‐rich pyridine derivatives. However, testing the catalysts at high alcohol concentrations at temperatures higher than 100 °C resulted in similarly moderate conversions in all cases.