文摘
This report describes a dehydration of fructose into 5-hydroxymethylfurfural (HMF) promoted by ionic liquids [Bmim]Cl and [HNMP][CH3SO3] in ethanol solvent. Two intermediates captured in time-dependent HPLC determinations are identified and structurally characterized by in situ 1H NMR and online ESI(+)-MS/MS. Studies on the influence of the ionic liquids (ILs) on the formation and transformation of the intermediates indicate that [HNMP][CH3SO3] promotes the formation of the intermediates, while [Bmim]Cl promotes their transformation. The contribution of the component ions of the ILs to the dehydration originates from their activation toward the leaving of OH on fructose or the intermediates via the formation of multiple hydrogen bonds. This kind of weak interaction appears only at low temperature. On the basis of the present study and the related literature, we propose a concerted mechanism for the binary IL-promoted conversion of fructose into HMF at room temperature.