Preparation, characterization and application of a green molten salt catalyst for the synthesis of bis(indolyl)methanes

A novel molten salt was synthesized easily by the reaction of sulfuric acid with 1,3-diaminopropane in water. The structure of the synthesized molten salt was investigated by 1H NMR, FT-IR and elemental analysis. Catalytic application of molten salt was studied in the synthesis of bis(indolyl)methanes at room temperature under solvent-free conditions. The most important advantages of this study are high yields, cleaner reaction profile, short reaction time, the avoidance of the organic solvents and easy work-up. In addition to the above-mentioned advantageous, excellent recyclability of the catalyst was environmentally benign and cost-effective.