Reactivities towards the benzoyloxy radical of monomers with beta-methyl groups

Summary Polymers of methyl methacrylate have been prepared at 60°C with benzoyl peroxide as initiator in the presence of methyl tiglate (MT), methyl crotonate (MC) or crotononitrile (CNL); they have been examined for end-groups derived from the initiator. The introduction of beta-methyl groups into methyl methacrylate, methyl acrylate and acrylonitrile (to give MT, MC and CNL respectively) increases reactivity towards the benzoyloxy radical. The effects can be explained in terms of the electron-repelling methyl groups activating the double bonds for reaction with the electrophilic benzoyloxy radical.