Results In Figures 1 and 2 plots of log ko vs. pH are shown for the disappearance of N-(P- phenylpropiony1) imidazole and N-isovalerylimidazole at 30" C in H20 (H= 0.1 M). Hydronium ion, hydroxide ion, and water-catalyzed reactions can be observed. The equation for ko is given in eq 1, where K, is the dissociation constant of the N-acyl-