EPR studies on the photofragmentation of 2,2-dialkyl-2-alkylaminoacetophenones

Abstract

Free radical reactions induced by photolysis of 2,2-dialkyl-2-alkylaminoacetophenone photocuring agents have been studied by continuous wave (CW) and time-resolved EPR spectroscopy. In all solvents α-cleavage from the triplet state is the major process. In hydrogen donor solvents it is accompanied by photoreduction followed by a rapid amine elimination from the ketyl radical inter-mediate. The benzoyl and α-aminoalkyl radicals resulting from α-cleavage readily add to acrylonitrile whereas radicals formed by photoreduction do not.