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[摘要]：The apparent second-order rate const. (kOH) for hydroxide-ion-catalyzed conversion of 1 to N-(2'-methoxyphenyl)phthalamate (4) is ~103-fold larger than kOH for alk. hydrolysis of N-morpholinobenzamide (2). These results are explained in terms of the reaction scheme 1Klobs?Klobs? where 3 represents N-(2'-methoxyphenyl)phthalimide and the values of k2obs/k1obs vary from 6.0 ?102 to 17 ?102 within [NaOH] range of 5.0 ?10-3 to 2.0 M. Pseudo-first-order rate consts. (kobs) for alk. hydrolysis of 1 decrease from 21.7 ?10-3 to 15.6 ?10-3 s-1 with an increase in ionic strength (by NaCl) from 0.5 to 2.5 M at 0.5 M NaOH and 35 癈. The values of kobs, obtained for alk. hydrolysis of 2 within [NaOH] range 1.0 ?10-2 to 2.0 M at 35 癈, follow the relationship kobs = kOH[HO-] + kOH'[HO-]2 with least-squares calcd. values of kOH and kOH' as (6.38 ?0.15) ?10-5 and (4.59 ?0.09) ?10-5 M-2 s-1, resp. A few kinetic runs for aq. cleavage of 1, N'-morpholino-N-(2'-methoxyphenyl)-5-nitrophthalamide (5) and N'-morpholino-N-(2'-methoxyphenyl)-4-nitrophthalamide (6) at 35 癈 and 0.05 M NaOH as well as 0.05 M NaOD reveal the solvent deuterium kinetic isotope effect (= kobsH2O/kobsD2O) as 1.6 for 1, 1.9 for 5, and 1.8 for 6. Product characterization study on the cleavage of 5, 6, and N-(2'-methoxyphenyl)-4-nitrophthalimide (7) at 0.5 M NaOD in D2O solvent shows the imide-intermediate mechanism as the exclusive mechanism. |
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