Polymer supported sulphanilic acid - A novel green heterogeneous catalyst for synthesis of benzimidazole derivatives

Polymer supported sulphanilic acid was synthesized and used as green, reusable and heterogeneous catalyst and duly characterized using chemical methods like determination of free hydroxyl content, epoxy equivalent weight and free sulphonic acid content as well as infrared spectroscopy and thermogravimetric analysis. The prepared catalyst was applied for one-pot synthesis of 2-substituted benzimidazoles from o-phenylenediamine and various aromatic aldehydes in absolute ethanol under thermal condition. Catalyst was separated from the product by simple filtration and could be reused for at least five times with almost retention in its efficiency. Due to three dimensional network structures, it shows high thermal stability and can be reused without any further purification.