101565-35-9Relevant academic research and scientific papers
Effects of methoxy-substituted metalloporphyrins in catalytic alkene epoxidation by n-Bu 4NHSO 5
Aghabali, Amineh,Safari, Nasser
experimental part, p. 335 - 342 (2010/11/21)
TPPMnOAc and four different kinds of manganese tetraphenylporphyrin acetates were synthesized using different numbers of methoxy substituents in various positions of the phenyl rings. These porphyrins were used as catalysts in the epoxidation of various alkenes with tetra-n-butylammonium hydrogen monopersulfate (n-Bu 4NHSO 5) as the oxidant and imidazole as the axial base. The following order of catalytic activity was obtained: TPPMnOAc ≥ T(2,3-OMeP) PMnOAc > T(4-OMeP) PMnOAc > T(3,4-OMeP) PMnOAc > T(2,4,6-OMeP) PMnOAc. By studying the UV-vis spectra in the reaction solution, the stability of the applied methoxy porphyrins and the effect of this factor on obtained yields were investigated. Lower catalytic activity in some of the methoxy porphyrins emphasized steric effects and special hydrogen bonding among the reaction elements. However, the stability of T(2,3-OMeP) PMnOAc under our reaction condition was considerable and high activity was observed. By adding small amounts of alcohol to the reaction solution, the effect of the solvent mixture was previewed and steps were taken to identify the active intermediate of the catalyst in these conditions. Copyright
Electrochemical reactivity of manganese(II) porphyrins. Effects of dioxygen, benzoic anhydride, and axial ligands
Creager,Murray, Royce W.
, p. 2612 - 2618 (2008/10/08)
Currents for electrochemical reductions of manganese(III) porphyrins in oxygenated, aprotic media correspond to passage of between one and two electrons per porphyrin, depending on the experimental time scale, the axial base present, and the particular porphyrin. The two-electron process corresponds to an ECE reaction sequence involving formation and subsequent reduction of an intermediate Mn(II)-dioxygen adduct. The formal potential of the second electron step is shown to be ca. -0.17 V vs. NaSCE for Mn(TPP)benzoate. Passage of the second electron is suppressed by strong axial bases and by competitive axial binding but is promoted by use of an axial anion that gives the most negative potential for passage of the first electron, Mn(TPP)benzoate being a specific example. The overall rate constant for the intermediate chemical step is estimated. In the presence of the added electrophile benzoic anhydride, and on a slower time scale, reduction by more than two electrons occurs by a process postulated to involve heterolysis of the O-O bond by the electrophile, producing an even more easily reduced, high-valent manganese-oxo porphyrin. The rate of electrophile attack is slower than that for dioxygen binding.
