KINETICS AND MECHANISM OF RUTHENIUM(III) CATALYZED OXIDATION OF ALIPHATIC ESTERS BY BROMAMINE-T IN AQUEOUS PERCHLORIC-ACID MEDIUM

Kinetics of ruthenium(III) catalysed oxidation of four aliphatic esters, viz. methyl, ethyl, n-propyl and n-butyl acetates by bromamine-T (BAT) have been studied in aqueous perchloric acid medium. The reactions followed zero order kinetics in [BAT] and [H+] and fractional order in [ester] and [Ru(III)]. Effects of added Cl- ion and varying ionic strength of the medium on the rate have been studied. The coefficients of rate-limiting steps have been computed at different temperatures by varying [ester] at each temperature. These constants were used to calculate the activation parameters from the Arrhenius plots. The proposed mechanism involves the formation of a complex between ester and Ru(III) which later disproportionates via a hydride ion abstraction by Ru(III) in a slow step. Applicability of Taft equation has also been tested.