EXPLORING Mⁿ⁺/SILICALITE-1 AS A CATALYST FOR BIGINELLI REACTION TO PRODUCE DIHYDROPYRIMIDINONE DERIVATIVES

A series of Mⁿ⁺/silicalite-1 was prepared to be used as a Lewis acid heterogeneous catalyst for a one-pot multicomponent Biginelli reaction. The catalysts were characterized by FTIR, XRD, NH₃-TPD, and BET. The mesoporous catalysts possess a pore diameter of 13.83 nm (138.3 Å), a surface area of 282.43 m²/g, and a pore volume of 0.98 cm3/g, which can facilitate the transport of reactants and products smoothly during the catalytic process. Besides the acidity of the catalyst, the maximum temperature of NH₃-desorption plays an important role in the catalytic activity. Cr³⁺/silicalite-1 showed the most active catalyst, while Zn²⁺/silicalite-1 showed the most selective one. Besides DHPM derivatives as a major Biginelli product, C₆-styril of DHPM and Knoevenagel products were isolated if the reaction was conducted using Cr³⁺/-and Fe³⁺/silicalite-1. Catalyst Cr³⁺/silicalite-1 can be used to produce DHPM attaching various substituents and showed a green catalyst potential due to its reusability capacity.