Immobilization of phosphomolybdic acid nanoparticles on imidazole functionalized Fe3O4@SiO2: a novel and reusable nanocatalyst for one-pot synthesis of Biginelli-type 3,4-dihydro-pyrimidine-2-(1H)-ones/thiones under solvent-free conditions

Abstract

This article introduces Fe₃O₄@SiO₂-imid-H₃PMo₁₂O₄₀ nanoparticles as heterogenic catalyst for the synthesis of 3,4-dihydropyrimidinones under solvent-free condition. This reaction proceeds through acetoacetate esters and aldehyde derivatives followed by cyclisation with a urea to the dihydropyrimidinone. Excellent yields of dihydropyrimidinones are obtained within a short reaction time. The suggested method offers several advantages such as short reaction times, high yields, easy purification, a cleaner reaction and ease of recovery and reusability of the catalyst by a magnetic field. Also, the aforementioned nanocatalyst can be easily recovered by an external magnetic field and reused for subsequent reactions at least 5 times without noticeable deterioration in catalytic activity. Particle size distribution, surface area, magnetic properties and percent of leaching of H₃PMo₁₂O₄₀ (PMA) after any reaction were investigated by dynamic light scattering (DLS), nitrogen physisorption method (BET) and Inductively Coupled Plasma (ICP) analyzer.