Abstract

An [Et₃NH][HSO₄] ionic-liquid catalyzed, intermolecular C−N bond formation for 1,2-disubstituted benzimidazole synthesis was achieved by the reaction of OPD and substituted aldehydes at ambient reaction conditions. Operational simplicity, use of easily available substrate and reagents, good yields (74–95 %) in short reaction time (4–18 min), simple work-up, and column chromatographic free synthesis are the remarkable features of this new protocol. The applicability of [Et₃NH][HSO₄] ionic-liquid as a green and inexpensive catalyst with good recyclability and compatibility with a broad range of functional group having heteroatom, electron-withdrawing, and electron-releasing groups manifested the sustainability, eco-friendliness, and efficiency of the present methodology. Moreover, the antioxidant studies of the synthesized compounds using DPPH and ABTS assays were appealing and several synthesized compounds showed significant antioxidant activity.