Deep eutectic solvents for synthesis of 5-hydroxymethylfurfural

One of the most versatile platform chemicals that can be produced from lignocellulosic biomass with acid catalysis is 5-hydroxymethylfurfural (HMF). Deep eutectic solvents (DES), which are mixtures of hydrogen bond acceptor and hydrogen bond donor compounds that form low-melting point complexes are environmentally-friendly and can be advantageously in HMF production as reaction phase, catalyst, co-catalyst, separation additive or as biphasic extractant. In this review, HMF production from biomass-derived carbohydrates along with the role of DES are highlighted with challenges being qualitatively assessed according to applicability, relative solvent cost, chemical safety, and R3 (reduce, reuse, recycle) indicators.