Immobilized-2-(4-thiazolyl)benzimidazole catalysts for the oxidative transformation of benzyl alcohol

The present work relates to the field of catalysis, specifically to the development of polymer-supported metal catalysts for the oxidation of benzyl alcohol while addressing catalyst reusability. We have investigated the oxidation of benzyl alcohol using chloromethylated polystyrene-supported 2-(4-thiazolyl)benzimidazole metal catalysts. These heterogeneous catalysts were synthesized by anchoring 2-(4-thiazolyl)benzimidazole on chloromethylated polystyrene and then loading Cu(II), V(IV), Fe(III), Ni(II), and Mn(II) ions on it. Metal loading (mmol per gram of resin) in different catalysts was found to be 0.96-1.39. Catalytic activity and selectivity of the polymer-supported catalysts were evaluated for the liquid phase oxidation of benzyl alcohol using hydrogen peroxide and tert-butylhydroperoxide as oxidants. The influence of concentration of the catalyst, reaction time, and temperature for the oxidation of benzyl alcohol was systematically investigated. A 67.8 % conversion rate was achieved utilizing a nickel catalyst under TBHP as the oxidant, whereas 88.1 % selectivity for benzaldehyde formation was attained with a nickel catalyst using TBHP as an oxidant. The mechanism of the oxidation of benzyl alcohol in the presence of the synthesized catalyst has also been proposed. Overall, the results highlight the potential of chloromethylated polystyrene-supported-2-(4-thiazolyl)benzimidazole metal catalysts as sustainable and effective catalysts for oxidation reactions in organic synthesis. KEY WORDS: Polymeric support, Heterogeneous catalyst, Recyclability, Hydrogen peroxide, tert-butylhydroperoxide, Oxidation Bull. Chem. Soc. Ethiop. 2026, 40(5), 1115-1134 DOI: https://dx.doi.org/10.4314/bcse.v40i5.13