Microwave‐Assisted One‐Pot Synthesis of Alkyl Levulinates From Post‐Harvest Vegetable Waste

Abstract The efficient production of fuels and chemical products from lignocellulosic biomass derivatives is a key objective in biorefinery research. Levulinic acid (LA), a valuable building block derived from lignocellulosic materials, serves as a precursor for alkyl levulinates via esterification with bio‐alcohols. These esters are widely used in industry as fuel additives, solvents, and fragrances. In this work, a microwave‐assisted one‐pot protocol is presented for the valorization of post‐harvest vegetable residues, specifically tomato, spinach, pepper, broccoli, red cabbage, beet, and artichoke, which are treated independently. The optimized reaction conditions for alkyl levulinate production, determined using the one‐variable‐at‐a‐time method, are as follows: 170 °C, 30 min, 150 mg of H₃PWO₄₀ (HPA), 2 mL of co‐solvent, and 2 mL of alcohol based on 0.3 g of biomass. Under these conditions, complete substrate conversion is achieved, with alkyl levulinate yields ranging from 25% to 55%. Green metrics are employed to evaluate the sustainability of the process, demonstrating its alignment with green chemistry principles. The one‐pot approach reduces intermediate separation steps, minimizing waste. These findings contribute to the development of more sustainable biomass‐to‐chemical conversion pathways, reinforcing the potential of alkyl levulinates as bio‐based platform chemicals and contributing to the Sustainable Development Goals (SDG).