Heteropoly-12-tungstophosphoric acid H3[PW12O40] over natural bentonite as a heterogeneous catalyst for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones

Heteropolyacid 12-tungstophosphoric acid H₃PW₁₂O₄₀] (TPA) immobilized over natural bentonite (bent) using the impregnation method. Prepared catalyst were well characterized by XRD, FT-IR and FeSEM. The catalytic activity of three catalysts 10%, 20% and 30% TPA/bent examined for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones known as Biginelli reaction. The catalyst 30% TPA/bent exhibited a high yield of the product towards the synthesis of a variety of dihydropyrimidones (DHPMs). The high yield of dihydropyrimidone (DHPM) was obtained in model reaction in ethanol, acetonitrile and solvent - free condition. The reusability test indicated that 5% of yield of product decreased after 5th cycle.