Mechanochemistry Unlocks direct cellulose conversion to 5-Hydroxymethylfurfural

5-Hydroxymethylfurfural (HMF) is a pivotal bio-based platform chemical, yet its direct production from inexpensive and abundant cellulose remains challenging due to the intrinsic recalcitrance of cellulose and the competing degradation of intermediates and products under acidic conditions. Herein, we report an AlCl₃-assisted mechanochemical strategy that couples catalytic Lewis acidity with ball-milling mechanical force to activate cellulosic feedstocks, enabling their efficient one-pot conversion to HMF. Detailed structural characterizations demonstrate that the synergistic interplay between AlCl₃ and mechanical stress disrupts the extensive hydrogen-bonding network and partially cleaves β-1,4-glycosidic linkages, leading to pronounced reductions in cellulose crystallinity and degree of polymerization and, consequently, markedly enhanced chemical reactivity. The resulting mechanochemically pretreated cellulose (BMM-AlCl₃) was directly converted into HMF without additional catalysts during the reaction step, as the Al species introduced during pretreatment served as the catalytic sites, affording a yield of up to 46.8%. By further optimizing the Brønsted/Lewis acid balance through controlled HCl addition, the HMF yield increases to 62.8%. Importantly, this pretreatment strategy is broadly applicable to diverse lignocellulosic biomass resources, including waste paper pulp, corncob residue, bamboo powder, and corn straw, consistently delivering high HMF yields. This work establishes an efficient and potentially scalable mechanochemical route for the valorization of cellulose and lignocellulosic biomass into HMF.