Sustainable corncob-derived sulfonated carbon catalysts for recyclable biginelli reactions in palm oil

This study presents a significant advancement in sustainable catalysis through the development of a sulfonated carbon catalyst derived from agricultural corncob waste for the green synthesis of dihydropyrimidinones (DHPMs) via the Biginelli reaction. Employing a simple, metal-free activation and sulfonation method, the optimized catalyst (SKAC1:1–600) exhibited a high acid site density (1.69 mmol g −1 ), excellent thermal stability, and outstanding catalytic efficiency, achieving up to 99.65 % yield under mild conditions (115 °C, 8 h). Notably, palm oil was employed as a biodegradable and reusable reaction medium, enabling both the catalyst and solvent to be recycled for at least four cycles with minimal loss in yield. The catalytic platform demonstrated broad substrate compatibility with various aldehydes and β-diketones. Comprehensive characterization (FTIR, XRD, SEM-EDS, TEM, BET, TGA, XPS, and NMR) confirmed the successful surface functionalization anfid structural integrity of the catalyst. Green metrics further highlighted the environmental credentials of the system, with an atom economy of 87–97 %, a low process mass intensity (PMI) of 15–21 g g −1 , and an E-factor of 14–20 g g −1 . This is the first report to integrate corncob-derived sulfonated carbon and palm oil in a synergistic, waste-to-wealth catalytic system, offering high yield, excellent reusability, and superior green performance. This work establishes a new benchmark in biomass valorization and eco-efficient multicomponent synthesis, providing a scalable and cost-effective solution that aligns with circular economy and green chemistry principles. A sustainable Biginelli reaction is developed using sulfonated carbon catalysts from corncob waste and recyclable palm oil. • A sulfonated carbon catalyst (SKAC1:1–600) was successfully developed from corncob waste using a simple, metal-free activation and sulfonation method. • The catalyst achieved up to 99.65 % yield of dihydropyrimidinones (DHPMs) under mild Biginelli reaction conditions (115 °C, 8 h). • Palm oil was employed as a biodegradable, renewable, and recyclable solvent, allowing multiple cycles of catalyst and solvent reuse. • The system demonstrated broad substrate compatibility, excellent reusability, and strong structural stability over several reaction cycles. • The process exhibited superior green metrics, including an atom economy of 87–97 %, a PMI of 15–21, and an E-factor of 14–20, setting a new benchmark for sustainable catalysis.