Hydrogen Peroxide Oxidation of Mustard-Model Sulfides Catalyzed by Iron and Manganese Tetraarylporphyrines. Oxygen Transfer To Sulfides versus H₂O₂ Dismutation and Catalyst Breakdown

Abstract

Fe(III)- and Mn(III)-meso-tetraarylporphyrin catalysis of H(2)O(2) oxidation of dibenzyl and phenyl-2-chloroethyl sulfides, 1, is investigated in ethanol with the aim of designing catalytic systems for mustard decontamination. The sulfide conversion, the sulfoxide and sulfone yields, the oxygen transfer from H(2)O(2) to the sulfide, and the catalyst stability depend markedly on the metal, on the substituents of its ligand, and on the presence or the absence of a cocatalyst, imidazole or ammonium acetate. With Fe, sulfones, the only oxidation products, are readily obtained whatever the ligand (TPP, F(20)TPP, or TDCPP) and the cocatalyst; the oxygen transfer is fairly good, up to 95% when the catalyst concentration is small ([1]/[Cat] = 420); the catalyst breakdown is insignificant only in the absence of any cocatalyst. With Mn, the sulfide conversion is achieved completely when the ligand is TDCPP or TSO(3)PP, but not F(20)TPP or TPP; a mixture of sulfoxide, 2, and sulfone, 3, is always obtained with [2]/[3] = 3.5-0.85 depending on the ligand and the cocatalyst (electron withdrawing substituents favor 3 and NH(4)OAc, 2). The catalyst stability is very good, but the oxygen transfer is poor whatever the ligand and the cocatalyst. These results are discussed in terms of a scheme in which sulfide oxygenation, H(2)O(2) dismutation, and oxidative ligand breaking compete. It is shown that the efficiency of the oxygen transfer is related not only to the rate constant of the dismutation route but also to the concentration of the active metal-oxo intermediate, most likely a perferryl or permanganyl species, i.e., to the rate of its formation.

H2O2 Oxidations Catalyzed by an Iron(III) Corrolazine: Avoiding High‐Valent Iron–Oxido Species?

“…This complex is a highly potent and selective catalyst for the sulfoxidation of thioethers under mild conditions with H 2 O 2 as the terminal oxidant. This result is of practical significance, because sulfoxidation catalysts are important for both chemical synthesis12 and the decontamination of warfare agents 13. Moreover, H 2 O 2 is a desirable terminal oxidant because it is inexpensive and does not produce environmentally toxic byproducts.…”

Fluorinated Porous Conjugated Polyporphyrins through Direct C−H Arylation Polycondensation: Preparation, Porosity, and Use as Heterogeneous Catalysts for Baeyer–Villiger Oxidation

“…According to reasonable mechanisms, high‐valent iron–porphyrin intermediate PorFeV=O is a key intermediate in the catalytic transformation in the main step. However, as a side reaction, it can also promote the oxidative breakdown of the porphyrin ligand, which leads to a decrease in the amount of effective porphyrin catalyst sites during recycling. Therefore, the yield of the catalytic reaction gradually decreases each time when using the recycled catalyst.…”

“…It is known that the formation of the iron–oxo complex as the active species is a key step during the oxidation reaction catalyzed by iron–tetraarylporphyrins . The Ruasse group reported that iron–tetrakis(pentafluorophenyl)porphyrin (F20TPPFe) possessed a high catalytic efficiency as a catalyst for the H 2 O 2 ‐induced oxidation of mustard models among a number of iron–tetraarylporphyrins with different phenyl substituents in the ligands. Fluorinated phenyl substituents of the iron–porphyrin not only are beneficial to the conversion, but also can stabilize the porphyrin to prevent catalyst breakdown.…”

Biomimetic Homogeneous Oxidation Catalyzed by Metalloporphyrins with Green Oxidants

“…Marques reported a new approach of mustard oxidation in a protic solvent with H 2 O 2 as an oxidant. 95 The results show that catalysis by Fe(III)-and Mn-(III)-tetraarylporphyrins (Scheme 14) can provide an interesting route to the transformation of mustard and related sulfides into sulfones. Differences in the behavior of Mn-and Fe-porphyrins for the efficiency in sulfide oxidation were also observed.…”