Ruthenium(III), osmium(VIII) and ruthenium(III) + osmium(VIII) catalysed oxidations ofi-propanol by N-bromosuccinimide in basic solution

The oxidation ofi-propanol (IPA) by N-bromosuccinimide (NBS) in basic solution was investigated separately in the presence of RuIII, OsVIII and RuIII + OsVIII ions. The order in [IPA] was found to be 0.7, 0.5 and 0.3 respectively in the above three cases in the concentration range studied. The order in [NBS] was unity in the presence of RuIII chloride but was found to be zero in the case of OsVIII and RuIII+OsVIII catalysis. The order in [metalion] was found to be nearly unity in all the three catalysed reactions. Increase in [−OH] increased the rate of reaction while addition of succinimide retarded the rate of reaction. Decrease in dielectric constantsof the medium decreased the rate of oxidation. The pseudo first order rate constants (k′), zero order rate constants (k0) and the formation constants (kf) of the substrate-catalyst complexes and the thermodynamic parameters have been evaluated. Suitable mechanisms in conformity with the experimental observations have been proposed for the three catalysed reactions.