Kinetics and mechanism of the homogeneous reaction between some manganese(III)-Schiff base complexes and hydrogen peroxide in aqueous and sodium dodecyl sulphate solutions

Abstract

The kinetics of the reaction between H2O2 and some Schiff base complexes of MnIII have been investigated in both aqueous and micellar sodium dodecyl sulphate (SDS) solution. The reaction rate is first order in both H2O2 and [complex], and inversely proportional to [H+]. The second-order rate constant increases in the sequence [Mn(salophen)(OAc)] > [Mn(salen)(OH2)]-ClO4 > [Mn(salen)(OAc)]H2O, where salen = N,N′-bis-(salicylidene)ethylenediamine and salophen = N,N′-bis-(salicylidene)-o-phenylenediamine. At SDS concentrations below the critical micellar concentration, there is almost no effect on the rate of reaction whereas at higher concentrations the reaction rate increases slightly. A mechanism involving MnII and a peroxo intermediate is proposed.