Effects of Mixed Aqueous?-?Organic Cosolvents on the Rates of Cleavage of N-(2′-Hydroxyphenyl)phthalimide (1) and N-(2′-Methoxyphenyl)-phthalimide (2) in Alkaline Media

摘要

Effects of Mixed Aqueous?-?Organic Cosolvents on the Rates of Cleavage of N-(2′-Hydroxyphenyl)phthalimide (1) and N-(2′-Methoxyphenyl)-phthalimide (2) in Alkaline MediaThe effects of mixed H2O-OCS (where organic cosolvents (OCS)=methanol, ethanol, 1-propanol, 2-propanol, 1,4-dioxan and acetonitrile) on the first-order rate constants, kobs, for hydrolysis of 1 at 1.0×10?3?M NaOH and 2 at 2.0×10?3?M NaOH show a nonlinear decrease in kobs with increasing contents of OCS. The kobs - decreasing sensitivity of mixed H2O-OCS solvents within 5-X% v/v OCS, where X ranges from 50 to 90, is ca 2- to 9-fold larger for hydrolysis of 2 than that of 1. This observed characteristic difference is attributed to the occurrence of different rate laws in these reactions, i.e. rate=kw [1?][H2O] and rate=kOH [2][HO?] in the hydrolyses of 1 and 2, respectively.