Harnessing the Potential of 5-Hydroxymethylfurfural: Investigating Solubility and Stability in Tailored Deep Eutectic Solvents.

The potential of 5-hydroxymethylfurfural (HMF) as a platform chemical for sustainable biobased products is widely recognized. However, its practical applications are often constrained by stability challenges. This study examines the solubility and chemical stability of HMF in 15 paradigmatic deep eutectic solvents (DES), formed by combining five hydrogen bond acceptors (HBAs: betaine, choline chloride, choline acetate, L-carnitine, and l-proline) and three hydrogen bond donors (HBDs: glycerol, ethylene glycol, and levulinic acid). Our findings reveal that HMF demonstrates high solubility and remarkable stability across the studied DES. Only a few cases of HMF degradation were observed and discussed, with specific degradation pathways identified in certain solvent mixtures. Notably, the HBAs within the DES play a crucial role in significantly enhancing the stability of HMF, establishing a foundation for its use as a renewable synthon in organic chemistry using environmentally benign solvents. These findings represent a significant step forward in aligning the synthetic design with the principles of green chemistry.