B. Gowda, B. Kumar
2003
Citations
0
Influential Citations
17
Citations
Journal
Oxidation Communications
Abstract
In an effort to study how the oxidative strength of N-chloro-arylsulphonamides varies with the substitution of either the electron-withdrawing or the electron-releasing groups into the benzene ring of the N-chloro-arylsulphonamides, the kinetics of oxidation of five amino acids (glycine, L-alanine, L-valine, L-phenylalanine and L-serine) by the parent and six p-substituted N-chloro-benzenesulphonamides has been studied, and the kinetic data and activation parameters are analysed and correlated. The substituted N-chloro-benzenesulphonamides employed are the sodium salts of N-chloro-p-methylbenzenesulphonamide, N-chloro-p-fluorobenzenesulphonamide, N-chloro-N-p-chlorobenzenesulphonamide, N-chloro-p-bromobenzenesulphonamide, N-chloro-p-iodobenzenesulphonamide and N-chloro-p-nitrobenzenesulphonamide. Two-pathway mechanism is considered to explain the experimental results. Effective oxidising species of the oxidants is Cl + in different forms. Therefore, the oxidising strength of N-chloro-arylsulphonamides depends on the ease with which Cl + is released from them, which in turn depends on the electron environment around the N-Cl bond. The study reveals that the introduction of substituents in the benzene ring of the oxidant affects both the kinetic and thermodynamic data for the oxidations. The electron-withdrawing groups such as halides and NO 2 lower the electron density on the nitrogen atom, thereby easing the release of Cl + and hence enhancing the oxidising strength of N-chloro-arylsulphonamides, while the electron-releasing groups such as CH 3 inhibit the ease with which Cl + is released and hence lower the strength of it as an oxidant. The effect of substituent in both the amino acids and the oxidants on the energy of activation E a and other parameters have also been correlated.