Mechanistic study of [RuCl3(H2O)2OH]−catalyzed oxidation of l-leucine by acidic N-bromophthalimide

Kinetic studies in homogenous Ru(III) catalyzed oxidation of l-leucine (Leu), by N-bromophthalimide (NBP) in the presence of perchloric acid have been made at 303 K using mercuric acetate as Br−ion scavenger. The reaction follows first-order kinetics with respect to [NBP]. In the lower concentration range of Leu and Ru(III) chloride, the reaction follows first-order kinetics but tends to zero at higher concentration. A positive effect of [Cl−] was observed in the oxidation of Leu. An increase in the rate of reaction with the decrease in dielectric constant of the medium was observed while negative effect was observed for [H+]. The rate of oxidation is unaffected by the change in [phthalimide (NHP)]. Rate of reaction decreased with increase in ionic strength of the medium. The main oxidation products of the reactions were identified as aldehyde, ammonia and CO2for the oxidation of Leu. From the effect of temperature (298–318 K) on the reaction rate, various activation parameters have been calculated and on the basis of these parameters, a suitable explanation for the reaction mechanism has been given.