Sustainable One-Pot Synthesis of Dihydropyrimidinones Using a Bio-Waste-Derived Magnetic Sulfonated SBA-16/NiAl-LDO Catalyst

This study presents the development of a novel magnetic heterogeneous catalyst derived from waste sugarcane bagasse ash for the efficient one-pot synthesis of dihydropyrimidinones via the Biginelli reaction. The catalyst combines mesoporous SBA-16 silica with NiAl-layered double oxides (LDO) and Fe3O4 nanoparticles, further functionalized with sulfonic acid groups to enhance surface acidity. The prepared SBA-16-SO3H/NiAl-LDO/Fe3O4 catalyst exhibited excellent structural properties, high surface area, and superparamagnetic behavior, enabling easy recovery and reuse. Under optimized green conditions (ethanol, 90 °C, 6 h), the catalyst delivered outstanding yields of up to 99% for various aromatic aldehydes, demonstrating superior performance compared to conventional silica-based and magnetic catalysts. Sustainability analysis, including green metrics such as Process Mass Intensity, E-factor, and Atom Economy, confirmed the process’s high efficiency and low environmental impact. The catalyst maintained high activity over multiple cycles with minimal efficiency loss, highlighting its potential for industrial applications with high turnover number (TON, 3,300) and turnover frequency (TOF, 550 h–1). This work introduces an innovative, biowaste-derived magnetic catalyst with excellent reusability and sustainability, offering a practical and environmentally friendly alternative for the synthesis of pharmaceutically valuable dihydropyrimidinones.