139361-29-8Relevant articles and documents
Imidazole-Catalyzed Hydrolysis of Substituted Benzoate Esters. A Detailed Kinetic and Mechanistic Study
Menegheli, Paulo,Farah, Joao P. S.,Seoud, Omar A. El
, p. 1610 - 1615 (2007/10/02)
Kinetic and mechanistic details of the imidazole-catalyzed hydrolysis of substituted phenyl benzoates in 10percent acetonitrile in water (V/V) were examined.The following 4 ester series were studied: p-nitrophenyl p-X-benzoates (X = CH3, H, Cl, CN, NO2, series I), p-Y-phenyl p-nitrobenzoates (Y = CH3, H, Cl, CN, NO2, series II), 2,4-dinitrophenyl p-X-benzoates (X = CH3O, H, Cl, CN, NO2, series III) and p-Y-phenyl 2,4-dinitrobenzoates (Y = CH3, H, Cl, CN, NO2, series IV).Based on: catalytic rate constants, activation parameters, kinetic solvent isotope effects, Hammett (ρ) values and the spectroscopic detection of the reaction intermediates, the following conclusions were reached: a) imidazole acts as a nucleophilic catalyst, i.e., the hydrolysis occurs via the intermediate formation of acylimidazole; b) the leaving group is the phenoxide ion; c) the rate limiting step is the decomposition of the tetrahedral intermediate that precedes the acylimidazole (series I, II and IV) or the attack of imidazole on the acyl group of the ester (series III). Keywords: Acylimidazoles / Catalysis / Chemical Kinetics / Isotope Effects / Reaction Mechanism
