Sustainable sulfonated carbon catalyst from yam bean waste for the Biginelli reaction in waste palm oil as a green solvent

This study presents a novel and sustainable catalytic platform for the Biginelli reaction, utilizing two abundant and underexploited waste resources: yam bean ( Pachyrhizus erosus ) biomass and waste palm oil. A sulfonated carbon catalyst, prepared from yam bean waste through a clean, metal-free process, exhibited a high total surface acidity (3.98 mmol g −1 ), excellent catalytic efficiency with DHPM yields of up to 94%, and good reusability over six consecutive cycles, retaining 76% yield in the final run. Combined with recycled palm oil as a renewable, green solvent, the system enabled the practical synthesis of dihydropyrimidinones (DHPMs) under mild conditions (5 wt% catalyst loading at 95 °C for 7 h), consistently achieving high yields across a broad substrate scope (70–94%). This dual valorization of food and agricultural waste not only minimizes environmental impact but also offers a practical, scalable alternative to conventional petroleum-based systems. Sustainability metrics, including a favorable E-factor, low Process Mass Intensity (PMI), and a high Green Motion™ score (77/100), further validate the green credentials of this approach. Beyond conventional green chemistry, this work delivers a real-world solution grounded in circular economic principles, transforming waste into functional value without compromising performance. The findings establish a promising benchmark for eco-friendly multicomponent synthesis and open new pathways for waste-derived catalyst and solvent systems in organic chemistry.