| Abstract
| - The rates of the hydrolyses of N-(o-hydroxyphenyl)phthalimide (1) and N-(o-methoxyphenyl)phthalimide(2), studied at different pH, show that the hydrolysis of 1 involves intramolecular general base (IGB)assistance where the o-O- group of ionized 1 acts as IGB and H2O as the reactant. The rate enhancementdue to the IGB-assisted reaction of H2O with ionized 1 is >8 × 104-fold. Pseudo-first-order rate constantfor the reaction of water with 2 is ∼2 × 103-fold smaller than the first-order rate constant (0.10 s-1) forpH-independent hydrolysis of 1 within the pH range of 9.60−10.10. Second-order rate constants (kOH)for hydroxide ion-assisted hydrolysis of ionized 1 and 2 are 3.0 and 29.1 M-1 s-1, respectively. Thesolvent deuterium kinetic isotope effect (dKIE) on the rate of alkaline hydrolysis of 1 and 2 reveals thatthe respective values of kOH/kOD are 0.84 and 0.78, where kOD represents the second-order rate constantfor DO--assisted cleavage of these imides (1 and 2). The value of kwH2O/kdD2O is 2.04, with kwH2O andkdD2O representing pseudo-first-order rate constants for the reactions of ionized 1 with H2O and D2O,respectively.
|
