Spectroscopic investigation on kinetics and mechanistic aspects to electron-transfer process into quinolinium dichromate oxidation of a high blood pressure drug captopril in acidic medium

This study investigated on kinetics of oxidation of captopril by QDC was studied spectrophotometically in acidic medium along with its mechanistic pathway. Such studies are greatly helpful in gaining an insight into the interaction of metal ions through the study of the mechanistic pathway of CPL in redox reactions. The oxidative product of captopril was found to be captopril disulfide was separated, and identified by FT-IR. A suitable free radical mechanism was proposed. The reaction exhibited first-order kinetics with respect to [oxidant] and fractional order in CPL. Consequently, the interaction between the complex species and CPL is supported kinetic orders of reaction by spectrophotometric verification, positive entropy of activation and the first-order rate constant increased with the increase in the dielectric constant and increase ionic strength of the medium. The reaction constants involved in the mechanism were computed and the overall activation parameters were evaluated which lend support to the proposed mechanism. (C) 2014 Elsevier B.V. All rights reserved.