Room-Temperature Ionic Liquid System Converting Fructose into 5-Hydroxymethylfurfural in High Efficiency

Abstract

This report describes a dehydration of fructose into 5-hydroxymethylfurfural (HMF) promoted by ionic liquids [Bmim]Cl and [HNMP][CH 3 SO 3 ] in ethanol solvent. Two intermediates captured in time-dependent HPLC determinations are identified and structurally characterized by in situ 1 H 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]-[CH 3 SO 3 ] 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.

The physicochemical properties of a room-temperature liquidus binary ionic liquid mixture of [HNMP][CH3SO3]/[Bmim]Cl and its application for fructose conversion to 5-hydroxymethylfurfural

“…24 For the roomtemperature conversion of fructose to HMF, some organic molecular solvents are used to formulate deep eutectic solvents (DES) with IL to lower the reaction temperature. 25,26 Our previous study has shown that the DES containing alcohol as hydrogen-bond donor has a negative effect on the HMF formation. The higher the polarity of the alcohol, the greater the negative effect.…”

“…The viscosity of the binary IL mixtures was measured on a Thermo Scientic HAAKE RheoStress 6000 rheometer at 25 C.…”

Rapid, High‐Yield Fructose Dehydration to 5‐Hydroxymethylfurfural in Mixtures of Water and the Noncoordinating Ionic Liquid [bmim][OTf]

“…Am echanistic study of fructose dehydration in ethanolw as performed by Zhang et al, [61] who demonstrated that two principal intermediates were formed prior to HMFf ormation, according to the mechanisms depicted in Scheme 1. By analyzing the kineticso ft he reaction, it was observed that the HMF yield did not increase furtherw hen these two peaks were no longer present, indicating that the reactionw as complete and the substratea nd the intermediates had been consumed.…”

Optimization and kinetic study of methyl laurate synthesis using ionic liquid [Hnmp]HSO 4 as a catalyst

“…Rad-Moghadam and co-workers used efficient NMP-ClSO 3 H salt ILs in the synthesis of δ-sultones [21]. Huang et al [22] reported a dehydration of fructose into 5-hydroxymethylfurfural promoted by ILs [Bmim]Cl and [NMP][CH 3 SO 3 ] in ethanol. In our previous study [23], the catalytic activity of the acidic IL 1-methyl-2-pyrrolidonium hydrogen sulfate salt ([Hnmp]HSO 4 ) in the synthesis of methyl laurate was studied without removing water during the esterification.…”