Effective biomass conversion to 5-HMF(5-hydroxymethylfurfural) is still a challenge and needs to be improved because of the 5-HMF importance as building blocks for valuable monomers and fuel precursors. We suggest for the first time utilization of low-cost metal-free Brønsted acidic Ionic liquid (IL) N,N-Diethyl-1,4-phenylenediamine hydrogen sulfate, [DPhDA]HSO₄ as a catalyst for the α-glucose dehydration to 5-HMF. Quantitative α-glucose conversion is achieved via optimizing the reaction condition: 91.4% 5-HMF yield with 30 mol% [DPhDA]HSO₄ in the presence of DMSO as a solvent at 160 °C in 30 min (TOF 6.1 h⁻¹). 3-fold increase in reaction time leads to higher (94%) 5-HMF yield at 160 °C with lower TOF 1.6 h⁻¹. The IL surprising catalytic performance is scrutinized with its amphiprotic nature (availability of basic and acidic spots in its structure (Fig. 1)). Further computational mechanistic studies revealed the function of the catalytic sites in the α-glucose dehydration. We calculated five-membered ring formation and water extrusion in one concerted transition state (TS2A, ΔG^‡ = 38.8 kcal/mol) following the α-glucose ring-opening (TS1, ΔG^‡ = 20.4 kcal/mol). Further four steps (sp³-s, C–H bond cleavages (TS3, TS6) and dehydroxylation (TS4A, TS5)) are quite straightforward to reach the product (5-HMF).

有效的生物质转化为5-HMF（5-羟甲基糠醛）仍然是一个挑战，由于5-HMF作为有价值的单体和燃料前体的基础材料很重要，因此有待改进。我们建议首次使用低成本的不含金属的布朗斯台德酸性离子液体（IL）N，N-二乙基-1,4-苯二胺硫酸氢盐[DPhDA] HSO ₄作为α-葡萄糖脱水制氢的催化剂5-HMF。通过优化反应条件可实现定量的α-葡萄糖转化：在DMSO作为溶剂的情况下，在160°C下于30分钟内（TOF 6.1 h ^-1），在30 mol％[DPhDA] HSO ₄的条件下，5-HMF的产率为91.4％。反应时间增加3倍，导致160°C时5-HMF产率更高（94％），TOF降低1.6 h^-1。IL具有令人惊奇的两性性质（其结构中存在碱性和酸性斑点（图1））来检查其令人惊讶的催化性能。进一步的计算机理研究揭示了催化位点在α-葡萄糖脱水中的功能。我们计算 了在α-葡萄糖开环后（TS1，ΔG ^•  = 20.4 kcal / mol），在一个一致的过渡态（TS2A，ΔG ^‡ = 38.8 kcal / mol）下的五元环形成和水挤出。进一步的四个步骤（sp ³ -s，CH键断裂（TS3，TS6）和脱羟基（TS4A，TS5）））十分简单，即可触及产品（5-HMF）。