Reaction of tert‐butoxyl radicals with electron‐rich α‐methylvinyl monomers

Abstract

The reactions of tert-butoxyl radicals with a-methylstyrene and with isopropenyl acetate were examined. Allylic hydrogen abstraction was shown to compete with addition to the double bond at the CH2 group. The proportion of abstraction relative to addition increases with increasing solvent polarity, however, this effect is more pronounced in the reactions of isopropenyl acetate than in those of a-methylstyrene.

Study on Radical Chemistry of Monoperoxycarbonates by α-Methylstyrene Dimer Trapping Technique

“…9 The reactions of t-butoxy radicals with a-methylstyrene at 60°C lead to 15% hydrogen abstraction from allylic hydrogens (85% addition to the double bond). 10 >-0-6-0-0+ ->-o-6-o· + -o+ Carbonate radicals were efficiently trapped by MSD in both cases. If carbonate radicals undergo decarboxylation, isopropoxy radicals should be trapped by MSD ( eq 5).…”

New Method in Free Radical Chemistry Using 2,4-Diphenyl-4-methyl-1-pentene as Radical Trapping Agent

“…For example, in the reaction of t-BuO · with (J(-methylstyrene, there was 85% addition to the double bond and 15% hydrogen abstraction from allylic hydrogens. 15 Thus, the somewhat lower recovery of peroxide radicals from 2a (75%) is ascribed to this hydrogen abstraction reaction. However, this side reaction does not become a significant problem since it has no effect on the reactivity between alkoxy addition to MSD and P-scission.…”

Study on Initiation Mechanisms of Peresters Using α-Methylstyrene Dimer (MSD) Trapping Technique

“…For example, it was reported that the reaction of t-BuO · with a-methylstyrene at 60°C leads to 15% hydrogen abstraction from allylic hydrogenes (85% addition to the double bond). 14 …”

“…Several methods for investigating the initiation mechanisms of free radical initiators have been developed: a tracer technique using 14 C labeled initiators (Bevington et al 1 -3 ), 13 C NMR technique using 13 C labeled initiators (Bevington et al 4 and Moad et al, 5), and nitroxide trapping technique (Rizzardo and Solomon 6 ). These methods have provided useful information on reactions of radicals such as benzoyloxy and t-butoxy radicals with vinyl monomers such as styrene and methyl methacrylate.…”