Solvent-promoted selective chemocatalytic hydroxymethylation of biomass furanic compounds

Functionalizing biomass-derived furanic chemicals is of great importance towards biorefinery processes but challenging, especially working at elevated substrate concentrations. We herein report the intervention of 1,4-dioxane co-solvent availably to catalyze hydroxymethylation of furfuryl alcohol (FA) in formalin over Hβ zeolite, giving high yield to 2,5-dihydroxymethylfuran (DHMF), a versatile building block. Impressively, the facilitating effect of 1,4-dioxane on DHMF production became more pronounced with increasing FA feeding concentration, and the yield raised from 19.5 % to 67.8 % from a high FA concentration of 10 wt%. The 1,4-dioxane served not only as a catcher of formaldehyde hydrate to access substrate FA, but also as a shield to restrain undesirable condensation side-reactions. The developed protocol demonstrated an excellent universality in boosting the hydroxymethylation of electrondrawing-group-free furanic molecules (e.g., furan, 2-methylfuran). The understanding of these solvation effects can be employed to effectively manipulate and improve the hydroxymethylation of furanic compounds.