Effect of redox potential on manganese-mediated benzylalcohol and sulfide oxidation

Abstract

Tridentate 1,3-bis(2 -Ar-imino)isoindolinato manganese(II) complexes were found to efficiently catalyze the mild oxidation of organic sulfides to sulfoxides and benzyl alcohols to benzaldehydes with mCPBA and PhIO, but they proved almost ineffective by the use of t BuOOH and H 2 O 2 at room temperature. The effect of electron-withdrawing and electron-donating substituents on the substrates (thioanisole and benzylalcohol), and the redox properties of the metal center by varying the aryl groups on the bis-iminoisoindoline were investigated, and showed a significant impact on the catalytic C-H oxidation and sulfoxidation reactions. Based on these results, including the linear correlations between the oxidation reactivity of the catalysts and Mn III /Mn II redox potentials, the Hammett correlation with ρ = −0.27 for 4R-PhSMe and ρ = −0.27 for 4R-PhCH 2 OH, electrophilic oxomanganese(IV) intermediate has been suggested as key oxidant. Furthermore, the small negative slope (−0.5) from the log k rel versus E o ox for 4R-PhSMe gives clear evidence for the direct oxygen atom transfer (OAT) mechanism instead of electron transfer (ET) mechanism between the Mn IV O and PhSMe.

Systematic analysis of the scientific-technological production on the use of the UV, H2O2, and/or Cl2 systems in the elimination of bacteria and associated antibiotic resistance genes

“…However, it is necessary to observe three reasons that may increase the interest in the study and use of the combined H 2 O 2 /Cl 2 system, which may be ignored by some authors: (i) to minimize parasitic reactions between H 2 O 2 and Cl 2 in a combined disinfection system, the doses of each compound must be carefully controlled and the concentration of oxidants and reaction by-products in the treated water must be regularly monitored (Fu et al 2023 ; Kribeche et al 2022 ; Wang et al 2019a , b , c ). (ii) Catalysts or co-oxidants may be added to improve the efficiency of the oxidation process and reduce the formation of toxic reaction by-products (Abo Atia et al 2021 ; Martínez-Pachón et al 2021 ; Meena et al 2021 ). (iii) When H 2 O 2 and Cl 2 are in solution, they can react with each other through an oxidation–reduction reaction, where Cl 2 is reduced to chloride (Cl − ) and H 2 O 2 is oxidized to water (H 2 O) through a chemical reaction that produces hydroxyl radicals (HO∙).…”

The Synthesis, Structural Characterization, and DFT Calculation of a New Binuclear Gd(III) Complex with 4-Aacetylphenoxyacetic Acid and 1,10-Phenanthroline Ligands and Its Roles in Catalytic Activity

“…The Fe (II) complex catalyst exhibits high CO2 selectivity (95%) [20]. Some metal complexes, such as the Mn(II) complex [24], Co(II) complex [25], Ru(III) complex [26], Cu(II) complex [27], and Pd(II) complex [28], also exhibit excellent catalytic activity and selectivity in benzyl alcohol oxidation. However, metal complexes have been rarely studied as catalysts for photocatalytic CO2 reduction and benzyl alcohol oxidation reactions.…”