Kinetic study and modeling of 3,4-dihydropyrimidinone (DHPM) formation via multicomponent Biginelli reaction catalyzed by ZnO prepared by sol–gel route

This work focuses on the kinetic investigation of 3,4-dihydropyrimidinone (DHPM) formation via the multicomponent Biginelli reaction in the presence of ZnO synthesized by the sol–gel method. The Biginelli reaction was conducted using benzaldehyde, ethyl acetoacetate, and urea as reactants, in the absence of solvent. The effects of various reaction parameters including catalyst loading, urea quantity, reaction time and reaction temperature on DHPM yield were evaluated. An increase in catalyst mass beyond a certain level negatively impacted DHPM yield, due to the enhanced occurrence of the Hantzsch reaction. In contrast, variation in urea quantity exhibited no significant effect on DHPM formation. In the kinetic study, performed at different reaction times with a catalyst loading of 10 mg, and assuming first-order with respect to both benzaldehyde and ethyl acetoacetate, an activation energy of 59.9 kJ·mol−1 and a pre-exponential factor of 2.01 × 108 L·mol−1·min−1·g−1 were determined.