Reactivities of Conjugated Dienes Towards the 1-Methyl-1-(methoxycarbonyl)ethyl Radical

Abstract

The relative reactivities of butadiene, isoprene, 2,3-dimethylbutadiene, 2,3-diphenylbutadiene and methyl methacrylate with the 1-methyl-1-( methoxycarbonyl )ethyl radical have been evaluated by using the 'polymer end-group method', and the data obtained compared with those for the same monomers in their reactions with the poly(methyl methacrylate ), 1-cyano-1-methylethyl and 1-phenylethyl radicals. The observed reactivity trends can be explained by variations in the Q and e values for the monomers, and show that the 1-methyl-1-(methoxycarbonyl)ethyl radical is a good model for the poly(methyl methacrylate ) radical. Further results indicate that a penultimate styrene unit does not affect the reactivity of a poly(methyl methacrylate ) radical, whereas a penultimate methacrylonitrile unit does.