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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 hydroxylation the first step of the reaction is the reversible formation of an intermediate adduct ‘A’ between the catalyst and the oxidant. The subsequent irreversible transformation of ‘A’ with rate constant k₂ leads to the formation of two high-valent oxometallo species, [RTDCPPMn^V(O)] and supposedly [RTDCPPMn^IV(O)]⁺&z.rad;. These species are in equilibrium and show distinct oxidation abilities towards the substrates.

The one-electron oxidation of 1,1-diphenyl-2-picrylhydrazine (DPPH) and Zn–tetra-tert-butylphthalocyanine (PcZn) to the corresponding stable radical (DPP&z.rad;) and π-radical cation (PcZn⁺&z.rad;) with peracetic acid in acetonitrile–acetic acid has been studied, in the presence of Mn^III complexes of meso-tetra(2,6-dichloro-4-R-phenyl)porphyrins (RTDCPPMnCl; R = CH₃O, H, Br, Cl or NO₂) as catalysts. The formation of a two-centre donor–acceptor complex of "catalyst–oxidant" type (adduct ‘A’) with rate constant k₁ is the first stage of the reaction. The balance of the electron donating properties of the porphyrin ring and electron accepting properties of Mn^III determines the formation of ‘A’, as shown by the independence of k₁ of catalyst structure. The influence of added acetic acid on the UV–Vis spectra of RTDCPPMnX in CH₃CN and on the oxidation rate of DPPH and PcZn evidenced that a molecule of AcOH is included in the internal co-ordination sphere of RTDCPPMnX and of the reaction intermediates. The rate constant k₂ for the irreversible transformation of ‘A’ into an equilibrium mixture of Mn^V and Mn^IV oxo-species (established in Part 1) must thus refer to the acetic acid adducts of Mn–porphyrins {[RTDCPPMn(AcOH)](X)}. A non-linear dependence of log k₂^rel on σ_para of the porphyrin substituents R has also been found. However, electron-withdrawing substituents are particularly effective for enhancement of the rate of formation of the high-valent oxomanganese species.

Mn(III)complexes of meso-tetra(o,o′-dichlorophenyl)porphyrin, tetra-tert-butyl-tetraazaporphine and 3,5-octanitrophthalocyanine are efficient catalysts of naphthalene oxidation by peracetic acid in acetonitrile solution. The pathways of the reaction and the nature of intermediates and final products depend on the catalyst structure. For meso-tetra(o,o′-dichlorophenyl)porphyrin MnCland tetra-tert-butyl-tetraazaporphine MnClthe single primary oxidation product is 1-naphthol. For 3,5-octanitrophthalocyanine MnCl, two pathways of naphthalene oxidation yielding 1-naphthol (as the primary product) and 1,4-naphthoquinone are proposed. The pathway of 1,4-naphthoquinone formation in the 3,5-octanitrophthalocyanine MnCl-catalysed reaction seems to involve two intermediates, 1,4-endo-peroxy-1,4-dihydro- and 2,3-epoxy-1,4-endo-peroxy-1,2,3,4-tetrahydronaphthalene.

cis-Stilbene (cSt) and 1,1-diphenyl-2-picrylhydrazine (DPPH) were used as substrates for kinetic investigations of the catalytic system based on MnIII-porphyrins and peracetic acid in CH₃CN. Catalysts employed were tetra-(2,6-dichlorophenyl)-porphyrinatomanganese chloride (TDCPPMnCl) 5, octanitrophthalocyaninatomanganese chloride (NO₂PcMnCl) 6 and tetra(tert-butyl)-tetraazaporphyrinatomanganese chloride (TAPMnCl) 7. It was found that for all these catalysts the first step of the reaction mechanism is the formation of an adduct ‘A' between the catalyst and AcOOH in a reversible way (k₁/k₋₁), followed by an irreversible stage (k₂) for the formation of MnV-oxo species. The oxidative capability of the adduct ‘A' was found to be dependent on the electronic structure of the catalyst, while the reactivity of Mn-oxo species is only slightly influenced by catalyst structure. The formation of the high-valent Mn-oxo species is the rate-determining step of alkene epoxidations as demonstrated by the same k₂ value obtained with catalyst 6 in the epoxidation of cSt and trans-stilbene (tSt). Catalyst stability was found to be dependent on solvent polarity, CH₃CN being the best reaction medium.

Manganese tetranitrotetra-tert-butyltetraazaporphine at low concentrations (0.02 mol%) effectively catalyses the oxidation of 2- methylnaphthalene by peracetic acid to give 2-methyl-1,4-naphthoquinone in 65% yield with a catalyst turnover number of 3100.