Kinetics and Mechanism of Oxidation of Creatine by N-Bromosuccinimide in Acidic Aqueous Medium


The kinetics and the mechanism of oxidation of creatine (AA) by N-Bromosuccinimide (NBS) in an acidic aqueous medium were examined under isolation conditions. Iodometric method was used to follow the unconsumed NBS at different time intervals. Mercuric(II) acetate was used as a scavenger to capture any Br- formed during the reaction and hence to avoid autocatalytic oxidation by bromine. Findings from stoichiometry measurements revealed that the reaction between AA and NBS was a 2:1 molar ratio. The kinetic study showed that the reaction was first order with respect to both AA and NBS. Increasing [H+] had a negative effect on the rate of reaction. The effect that varying the solvent composition has on the rate of reaction was investigated, and it was found that the reaction rate decreased as the dielectric constant of the solvent increased.  The temperature dependence was determined under fixed experimental conditions, from which thermodynamic parameters were calculated. From the proposed mechanism, a rate law was established that was in strong agreement with experimental kinetics.