An efficient facile and one-pot synthesis of 2-arylsubstituted benzimidazole derivatives using 1-methyl-3-(2-oxyethyl)-1H- imidazol-3-ium-borate sulfonic acid as a recyclable and highly efficient ionic liquid catalyst at green condition

1-Methyl-3-(2-oxyethyl)-1H-Imidazol-3-ium-Borate Sulfonic Acid ([MOEI]-BSA) was easily prepared and used as a new and highly efficient solid acid catalyst for the synthesis of benzimidazole derivatives with high isolated yields. Various substituted benzimidazoles were synthesized by a combination of o-phenylenediamines and aldehydes in the presence of [MOEI]-BSA with excellent yields in water and under a mild and green reaction conditions. This method is also applicable for precursors such as aromatic and unsaturated aldehydes and o-phenylenediamines. Addition of organic part to BSA and synthesis of [MOEI]-BSA as a new Bronsted acidic ionic liquid (BAIL) improved the efficiency of this catalyst.