STRUCTURE AND REACTIVITY IN INTRAMOLECULAR CATALYSIS. CATALYSIS OF SULFONAMIDE HYDROLYSIS BY THE NEIGHBORING CARBOXY GROUP.

Article abstract of DOI:10.1021/ja00517a034

A report is presented on kinetic data for the intramolecular carboxy-catalyzed hydrolysis of 26 sulfonamides in water and in some mixed aqueous solvents. The effective molarity of the carboxyl group is very high (up to ca. 10**8 M) but depends markedly on the structure of the sulfonamide. Substituent effects within a series of 4- and 5-substituted 2-carboxy-N,N-dimethylbenzenesulfonamides are interpreted in terms of nucleophilic catalysis. The role of nonbonded interactions in the initial state and in the transition state is discussed. By using X-ray structural data where available, strain effects have been elucidated for a series of sulfonamides in which the sulfonamide and carboxyl groups are held cis to each other. Striking differences from the corresponding carboxamide systems are attributed to differences in transition state geometries and steric effects.