Kinetics and Mechanism of Ruthenium(III) catalysed Oxidation of Aliphatic Esters by Bromamine-T in Aqueous Perchloric Acid Medium

Department of Post-Graduate Studies and Research in Chemistry, Mangalore University, Mangalagangothri-574 199 Manuscript received 19 March 1990. accepted 9 April 1991 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 [RuIII]. 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 RuIII which later disproportionates via a hydride ion abstraction by RuIII In a slow step. Applicability of Taft equation has also been tested