Structure-Reactivity Correlations in the Dissociative Hydrolysis of 2',4'-Dinitrophenyl 4-Hydroxy-X-benzenesulfonates.
The hydrolysis reactions of several title esters in water at 60 degrees C follow the rate law k(obs) = (k(a) + k(b)[OH(-)])/(1 + a(H)/K(a)), where K(a) is the ionization constant of the hydroxy group of the ester and k(b) is the second-order rate constant for the S(N)2(S) attack of hydroxide ion on the ionized ester. Hammett and Brønsted correlations are consistent with a previous proposal that the mechanism related to k(a) is dissociative. An unusual relationship between k(a) values and redox equilibrium constants for substituted quinones is found to hold: this finding further supports the dissociative nature of the pathway related to k(a).
Cevasco
Giorgio
G
C.N.R., Centro di Studio per la Chimica dei Composti Cicloalifatici ed Aromatici, Via Dodecaneso 31, 16146 Genova, Italy, and Dipartimento di Chimica, Via Vienna 2, Università di Sassari, 07100 Sassari, Italy.
Thea
Sergio
S