Structurally-dependent catalytic activity of modified cellulose with different graft side chains in the preparation of 5-hydroxymethylfurfural via a biphasic system

Derivatization of cellulose remarkably enhances its conversion reactivity. • Cellulose acetate delivers 9.4-fold higher HMF yield than pristine cellulose. • Glycosidic-bond hydrolysis is the rate-limiting step in cellulose conversion. • Structure-reactivity insights enable efficient valorization of cellulose waste to HMF. Native cellulose’s recalcitrant hydrogen-bond network severely limits its efficient conversion to 5-hydroxymethylfurfural, a versatile biobased platform chemical. Chemical modification can disrupt cellulose crystallinity and boost reactivity, but systematic comparisons between esterification and etherification modifications, and the influence of grafted carbon chain length, remain largely unaddressed. This work investigates seven industrially relevant modified celluloses in an AlCl 3 /γ-valerolactone/water biphasic system, integrating reaction screening, structural characterization, density functional theory calculations and kinetic analysis. Cellulose acetate with the shortest acetyl side chain achieves the highest HMF yield of 49.3 mol% at 150 °C, 9.4 times that of native α-cellulose. Kinetic modeling identifies glycosidic bond hydrolysis as the rate-limiting step, with an apparent activation energy of only 46.0 kJ/mol, far below typical values for native cellulose systems. These findings clarify the structure-reactivity relationship and offer a pathway for valorizing modified cellulose wastes. Download: Download high-res image (380KB) Download: Download full-size image