Kinetics and mechanism of the alkaline hydrolysis of maleimide

Article abstract of DOI:10.1002/jps.2600731227

The kinetics of hydrolysis of maleimide was carried out within the [OH^-] range of 2.46 x 10^-6 to 2.0 M at 30°C. The observed pseudo-first-order rate constants, k(obs), follow the empirical equation: k(obs) = (A₁[OH^-] + A₂[OH^-]²)/(1 + A₃[OH^-]). Both ionized and un-ionized forms of maleimide have been suggested to be involved in hydrolysis. The nucleophilic attacks by hydroxide ion at the carbonyl carbon of both ionized and un-ionized maleimide and by water at the carbonyl carbon of ionized maleimide to form tetrahedral intermediates are considered to be the rate-determining steps. The observed results obtained at different 1,4-dioxane-water compositions have revealed an increase in k(obs) with a decrease in 1,4-dioxane content which could be attributed to the higher polarity of the transition state compared with the reactant state.