In a review article [Accounts Chem. Res., 2, 217 (1969)] is a summation of our work up to 1968. In this review we summarized the activity of polyvinyl imidazole and copolymers in esterolytic reactions. We explained the increased reactivity of these polymeric reactants in terms of cooperative effects and electrostatic factors. In 1967, we blundered into the extremely interesting discovery that long-chain esters provided us with enormous acceleration of rates at room temperature and we have attributed this in “general” terminology to apolar bonding as a third factor to understand the high reactivity of these synthetic macromolecules. Reference 1 describes our recent published work. We are heavily emphasizing the apolar bonding concept. Related work which conceptually can be regarded as similar to our own discovery was carried out by the group of Professor Irving M. Klotz at Northwestern(2), the group of Professor Kabanov at the University of Moscow(3), and the group of Professor Kunitake(4). This lecture will briefly review the background of the problem and discuss in detail the catalysis of esterolytic reactions by water-soluble copolymers of vinyl imidazoles and vinylamines. Synthetic macromolecules containing pendant imidazole groups have been used as catalysts for the hydrolysis of esters. This report extends that study to copolymers of 4(5)-vinylimidazole and vinylamine. The latter component renders these polymers water soluble and, therefore, their catalytic activity could be studied in a totally aqueous environment. The precursor for the vinylamine monomer used for these copolymerizations was N-vinyl-t-butylcarbamate which, in turn, was prepared from vinyl isocyanate. Extremely large rate enhancements were observed with these catalysts for hydrolyses of activated esters and these were attributed to cooperative, electrostatic and hydrophobic effects. The large cooperative effects were due to tight coiling of these copolymers in water, increasing the proximity of imidazole groups for interaction. The highly aqueous media in which these esterolysis could be carried out with these copolymers resulted in very large hydrophobic effects with long chain ester substrates. Less aqueous environments led to dramatic rate decreases. Esterolytic studies were also carried out under conditions of excess substrate which showed typical steady-state kinetics from which rates of deacylation of the catalyst could be determined. The fraction of imidazoles in these copolymers that were acylated under steady-state conditions were quite low. © 1979, Walter de Gruyter. All rights reserved.
