Abstract
The effect of a cationic surfactant, cetyltrimethyl ammonium bromide (CTAB), on the rate of alkaline hydrolysis of four p-substituted benzene sulfonyl fluoride derivatives was investigated. The p-substituents were classified into clectron-withdrawing (p-NO2) and electron-donating (p-NH2, p-CH3CONH and p-CH3) groups. These different groups produced opposite effects on the rate of alkaline hydrolysis of the corresponding esters in the presence of CTAB. Our investigation on the alkaline hydrolysis of various p-substituted benzene sulfonyl fluorides indicated an inhibitory effect of CTAB in all cases irrespective of the nature of the p-substituent. Solubility studies and multiplot analysis of the kinetic data clearly indicated that the various substituents were appreciably partitioned into the micellar phase. The solubility studies further indicated complexation between the substrate and surfactant. It may be concluded that in sulfonyl fluoride-CTAB systems, the extent of interaction between the substrate and surfactant may be the primary factor determining the type of effects observed instead of the electron activity of the p-substituent. The substrate solubilization in the submicellar region may also play a secondary role.
