Initiation mechanisms in radical polymerization: Reaction of isopropoxyl radicals with methyl methacrylate

The radical trapping technique employing 1,1,3,3-tetramethyl-1,3- dihydroisoindole-2-yloxyl 2 as a scavenger has been used to study the reaction of isopropoxyl radicals with methyl methacrylate 1. Addition to the unsubstituted (tail) end of 1 and hydrogen abstraction from the α-methyl group of 1 were the major pathways of the reaction; the ratio of addition-abstraction was 7:1. The formation of alkoxy amines 6 and 8 was an unusual feature of the reaction. These two products appear to be derived from the reaction between 2-hydroxy-1,1,3,3-tetramethyl-1,3-dihydroisoindole and 1. The mechanism of this reaction is discussed.