Knoevenagel condensation in aqueous media promoted by 2,2′-bipyridinium dihydrogen phosphate as a green efficient catalyst

A 2,2′-Bipyridine-based ionic compound named 2,2′-bipyridinium dihydrogen phosphate was synthesized by addition of phosphoric acid to a solution of 2,2′-Bipyridine in dichloromethane. After the characterization using FT-IR, mass, 1H, 13C and 31P NMR techniques, it was used as a Bronsted dicationic acidic catalyst for the promotion of the synthesis of 2-arylidene malononitrile and 5-arylidene barbituric acid derivatives via Knoevenagel condensation reaction in water. Some of the advantages of this method are the utilization of an easy preparable, cost-effective and eco-friendly organic salt as a catalyst within high rates and yields of the reactions, simple and quick work-up and acceptable reusability of the catalyst.