Selective photocatalytic oxidation of aromatic alcohols to aldehydes with air by magnetic WO₃ZnO/Fe₃O₄. <i>In situ</i> photochemical synthesis of 2-substituted benzimidazoles

Recently, visible light-driven organic photochemical synthesis has been a pioneering field of interest from academic and industrial associations due to its unique features of green and sustainable chemistry. Herein, WO₃ZnO/Fe₃O₄ was synthesized, characterized, and used as an efficient magnetic photocatalyst in the preparation of a range of 2-substituted benzimidazoles <i>via</i> the condensation of benzyl alcohol and <i>o</i>-phenylenediamine in ethanol at room temperature for the first time. The key feature of this work is focused on the <i>in situ</i> photocatalytic oxidation of benzyl alcohols to benzaldehydes under atmospheric air and in the absence of any further oxidant. This new heterogeneous nanophotocatalyst was characterized <i>via</i> XRD, FT-IR, VSM and SEM. Short reaction time, cost-effectiveness, broad substrate scope, easy work-up by an external magnet, and excellent product yield are the major advantages of the present methodology. A number of effective experimental parameters were also fully investigated to clear broadness and generality of the protocol.