Mechanistic investigation of oxidation of ciprofloxacin by sodium n-chlorobenzenesulphonamide in acid medium. A kinetic study

The kinetics of oxidation of ciprofloxacin (CPF) by sodium N-chlorobenzenesulphonamide or chloramine-B (CAB) in HCI medium at 30 °C shows first order dependence each on oxidant, substrate and H + ion concentrations, but is independent of Cl -. The reaction is subjected to changes in: (a) ionic strength; (b) dielectric constant, and (c) added reaction product, and the subsequent effects on the reaction rate are studied. The reaction was studied at different temperatures, and activation parameters have been computed for the overall reaction from the Arrhenius plot. Oxidation products were identified by TLC and spectral (IR and NMR) analysis. A mechanism involving interaction of conjugate acid (PhSO 2NHCl) and substrate giving an intermediate complex in a slow step has been suggested. The proposed mechanism and the derived rate law are consistent with the observed kinetics.