Study on radical chemistry of monoperoxycarbonates by α-methylstyrene dimer trapping technique

Abstract

The initiation mechanisms of ΟΟ-t-butyl Ο-isopropyl peroxycarbonate (BuI) and ΟΟ-t-hexyl Ο-isopropyl peroxycarbonale (Hexl) were studied at 140°C by α-methylstyrene dimer (MSD) trapping. Alkoxycarbonyloxy radicals (carbonate radicals) produced from the peroxides were trapped by MSD almost quantitatively, indicating that decarboxylation of carbonate radicals was too slow to compete with addition to the styreneic double bond even at high temperature. The hydrogen abstraction ability of these peroxides was evaluated in a mixture of MSD and cyclohexane. Hydrogen abstraction ability of Hexl was much lower than that of BuI. In bulk styrene polymerization, BuI acted as a more efficient initiator than the perester type initiator of t-butyl peroxylaurate, keeping high initiator efficiency up to high monomer conversions.