Abstract
The isotopic acyl exchange between p-nitrophenyl acetate and acetic acid was studied in neutral organic solvents in the presence of several kinds of bases. The kinetics showed the first order dependency of the exchange rate on the base. The exchange reaction is shown to consist of the two steps. The preliminary step produced the pyridine-acetic acid complex which participated in the true exchange step. The effect on the exchange rate of structural changes of the base was attributed to changes in base strength and steric effect, and they affected the preliminary equilibrium. Solvent effect on the exchange rate and curvature of k vs. [Base] were due mainly to effect on the true exchange step and partly to effect on the preliminary step.
