REACTIONS OF THE ETHYL RADICAL: IV. ADDITION TO VINYL MONOMERS

Abstract

The Arrhenius parameters have been measured for the addition of the ethyl radical to a representative selection of vinyl monomers in the gas phase. The wide range of reactivity observed was almost entirely due to the variation of the energy of activation, from 3.4 ± 0.4 kcal/mole for acrylonitrile to 6.9 ± 0.5 kcal/mole for vinyl acetate. No significant variation was found among the values of the pre-exponential factors, indicating uniformity of steric conditions at the site of radical attack. The rate constant for the addition of the ethyl radical is considered as an alternative to the copolymerization parameter Q0 as an index of the intrinsic reactivity of a monomer at a given temperature.