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 investi gated in water, acetonitrile, propylene carbonate, and 1,4-dioxane at diffe rent temperatures, the observed rates can be evaluated with the help of a r eaction mechanism consisting of two competitive reaction paths; the first i s the bimolecular nucleophilic substitution of the phenol moiety by imidazo le; the second path is performed via general base catalysis by a second imi dazole molecule. The rate constants of the bimolecular reaction are quantit atively correlated with the four-parameter Taft-Kamlet equation for solvent effects on chemical reactions. A qualitative interpretation of the data sh ows that the two reaction paths are influenced to the same extent by the so lvent.