Production of 5-Hydroxymethyl-2-furan Carboxylic Acid Using Biobased Silver Nanoparticles in Deep Eutectic Substrate Reaction Mixtures

Recently, the green synthesis of metal nanoparticles (NPs) using plant constituents and extracts has attracted much attention. Biologically active substances with antioxidant/reducing, nontoxic, low-cost properties and stabilizing agents are highly sought after. Among these substances, Stevia is a potentially interesting raw material for the preparation of biologically active extracts and the green synthesis of colloidal NPs. In our work, the synthesis of Ag NP colloids using Stevia plant leaf extracts was optimized. The synthesized Ag NPs were characterized by XRD, FE-SEM, TEM, HR-TEM, DLS, UV-vis, and XPS, and their performance as a cheap, biological, and available catalyst was evaluated for the selective synthesis of 5-hydroxymethyl-2-furan carboxylic acid (HMFCA) from the platform molecule 5-hydroxymethylfurfural (5-HMF). In order to have a more sustainable process, this catalytic oxidation was carried out in various deep eutectic mixtures as a cool, green, and environmentally friendly reaction medium. The target molecule was obtained in an impressive 98% yield of HMFCA (45 min, 50 degrees C) and the Stevia-derived catalyst is easily removed from the reaction mixture and recycled up to six times without loss of activity.