Magnetic mesoporous zirconium phosphate (MMZP-Pr-SO3H): a highly efficient and reusable catalyst for sustainable preparation of phenyl tetrazole and 2-substituted benzoazoles†

Abstract

Based on the synthesis of mesoporous zirconium phosphate in the presence of magnetic nanoparticles (NPs) and its functionalization with propyl sulfonic acid groups, a new and effective heterogeneous acidic catalyst (MMZP-Pr-SO₃H) was prepared. It was attempted to alter the catalyst's properties in this study in order to boost reactant conversion yield and remove unselective reaction pathways by offering complementary characterization. MMZP-Pr-SO₃H was used for the eco-friendly and efficient preparation of various tetrazole derivatives through condensation of aryl nitriles and sodium azide in water solvent at 60 °C. This protocol was also practical for benzoazole (benzimidazole, benzoxazole, and benzothiazole) synthesis starting from the in situ oxidation of benzyl alcohol, which demonstrates the dual role of the MMZP-Pr-SO₃H catalyst in oxidation and condensation reactions. For both investigated reactions quantitative conversion of the desired product was obtained and the catalyst was simply separated from the reaction mixture by employing an external magnetic field. The MMZP-Pr-SO₃H catalyst was regenerated and reused for at least 6 runs without a significant decrease in reaction yield. With the aid of lenses on catalyst active sites, the structural characteristics of the recycled catalyst were thoroughly examined. In contrast to our earlier attempts to study the structural features of the MZP and ZP substrates and use them as catalysts for organic reactions, the MMZP-Pr-SO₃H catalyst offers a sustainable and clean synthetic methodology for the large-scale preparation of derivatives of tetrazoles and benzoazoles.