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.