Kinetic and mechanistic study of the oxidation of carvedilol by peroxodiphosphate

The oxidation of carvedilol (CARV) by peroxodiphosphate (PDP) in acidic methanol?water solutions was investigated under pseudo-first order kinetics conditions. A two-step electrophilic oxidation mechanism is proposed, where, in the first step, the PDP electrophile reacts with CARV to form an intermediate species, while in the second step, the intermediate is converted by PDP into the end product, carbazole-1,4-quinone. Kinetic studies revealed that both steps depend on PDP and acid concentrations. The determined rate constants showed that the second step is tenfold slower than the first step. Temperature-dependent rate measurements yielded thermodynamic parameters consistent with a polar mechanism, showing comparable enthalpy and entropy changes in the transition states of both reaction steps. These results provide valuable insights into the oxidation of carvedilol by PDP, highlighting its potential as a candidate oxidizing agent for preformulation studies.