Kinetic studies on the interactions of manganese-porphyrins with peraceticacid. Part 1. Epoxidation of alkenes and hydroxylation of aromatic rings

The mechanism of peracetic acid interactions with Mn-III complexes of meso- tetra(2,6-dichloro-4-R-phenyl)porphyrins (RTDCPPMnCl; R=CH3O, H, Br, Cl or NO2) in acetonitrile-acetic acid has been studied. Analysis of the kinetic data revealed that both in cis-stilbene epoxidation and naphthalene hydroxy lation the first step of the reaction is the reversible formation of an int ermediate adduct 'A' between the catalyst and the oxidant. The subsequent i rreversible transformation of 'A' with rate constant k(2) leads to the form ation of two high-valent oxometallo species, [RTDCPPMnV(O)] and supposedly [RTDCPPMnIV(O)](+.). These species are in equilibrium and show distinct oxi dation abilities towards the substrates.