Role of hydrogen bonding in the mechanism of hydrogen atom abstraction from alkyl-substituted phenols by polyvinyl acetate radicals

Abstract

Application of a novel dilution technique to the kinetic study of the inhibited radical polymerisation of vinyl acetate provided experimental evidence for the following conclusions. (i) The title reaction proceeds via simultaneous pathways owing to hydrogen bonding between phenols and vinyl acetate. (ii) The influence of hydrogen bonding on the reactivity at 50 °C depends on the type of substitution. The free phenol is more reactive than the bonded form if at least one of the ortho-positions is unsubstituted. The hydrogen bonded species is more reactive than the free form for 2,6-dialkylphenols. (iii) The individual reaction paths are associated with significantly differing Arrhenius parameters.