N-sulfonic acid pyridinium-4-carboxylic acid chloride as a novel and efficient catalyst for the condensation reaction of aldehyde with thiobarbituric acid and ammonium acetate

N-sulfonic acid pyridinium -4-carboxylic acid chloride {[Pyridine-N-SO3H-4-COOH]Cl} was synthesized, identified and applied as an effective catalyst for the preparation of pyrido[2,3-d:6,5-d ]dipyrimidines by the condensation reaction of various aldehyde with 2-thiobarbituric acid and ammonium acetate under solvent-free conditions. The structure of catalyst was studied by various techniques including FT-IR, 1HNMR, 13CNMR, SEM, EDS, TEM, TGA, DTG and XRD analyses.