Kinetics of the reaction of substituted 4-nitrophenyl benzoates with benzenethiol in the presence of potassium carbonate in dimethylformamide

The effect of the substituent nature on the rate and activation parameters of transesterification of a series of 4-nitrophenyl benzoates with benzenethiol in dimethylformamide in the presence of potassium carbonate was studied by the competing reaction method. In all cases, change of the Gibbs energy of activation is determined mainly by variation of the enthalpy of activation. 4-Nitrophenyl benzoates having electron-withdrawing substituents in the benzoyl fragment were found to fit an isokinetic relation with an isokinetic temperature β of 318 K. Enthalpy-entropy compensation effect was observed in the reactions with all the examined 4-nitrophenyl benzoates. The relation between the reactivity and polarizability of nucleophilic center in S-and O-nucleophiles is discussed.