Investigations on Substituent and Solvent Effects of Solvolysis Reactions. VIII. The Influence of Water and Nonaqueous Solvents on the Imidazolysis of 4-Nitrophenyl Acetate

The aminolysis reaction of 4-nitrophenyl acetate with imidazole was investigated in water, acetonitrile, propylene carbonate, and 1,4-dioxane at different temperatures. the observed rates can be evaluated with the help of a reaction mechanism consisting of two competitive reaction paths; the first is the bimolecular nucleophilic substitution of the phenol moiety by imidazole; the second path is performed via general base catalysis by a second imidazole molecule. The rate constants of the bimolecular reaction are quantitatively correlated with the four-parameter Taft–Kamlet equation for solvent effects on chemical reactions. A qualitative interpretation of the data shows that the two reaction paths are influenced to the same extent by the solvent.