| Abstract
| - Fe(III)- and Mn(III)-meso-tetraarylporphyrin catalysis of H2O2 oxidation of dibenzyl and phenyl-2-chloroethyl sulfides, 1, is investigated in ethanol with the aim of designing catalytic systems formustard decontamination. The sulfide conversion, the sulfoxide and sulfone yields, the oxygentransfer from H2O2 to the sulfide, and the catalyst stability depend markedly on the metal, on thesubstituents of its ligand, and on the presence or the absence of a cocatalyst, imidazole or ammoniumacetate. With Fe, sulfones, the only oxidation products, are readily obtained whatever the ligand(TPP, F20TPP, or TDCPP) and the cocatalyst; the oxygen transfer is fairly good, up to 95% whenthe catalyst concentration is small ([1]/[Cat] = 420); the catalyst breakdown is insignificant onlyin the absence of any cocatalyst. With Mn, the sulfide conversion is achieved completely when theligand is TDCPP or TSO3PP, but not F20TPP or TPP; a mixture of sulfoxide, 2, and sulfone, 3, isalways obtained with [2]/[3] = 3.5−0.85 depending on the ligand and the cocatalyst (electronwithdrawing substituents favor 3 and NH4OAc, 2). The catalyst stability is very good, but the oxygentransfer is poor whatever the ligand and the cocatalyst. These results are discussed in terms of ascheme in which sulfide oxygenation, H2O2 dismutation, and oxidative ligand breaking compete. Itis shown that the efficiency of the oxygen transfer is related not only to the rate constant of thedismutation route but also to the concentration of the active metal-oxo intermediate, most likely aperferryl or permanganyl species, i.e., to the rate of its formation.
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