Production of 5‐Hydroxymethylfurfural from D‐Fructose in Low‐Transition‐Temperature Mixtures Enhanced by Chloride Anions and Low Amounts of Organic Acids

Abstract

The use of safe and sustainable solvents able to solvate reagents and to catalyze their reactions at temperatures below 100°C is an innovative strategy to develop future lignocellulosic biorefineries. Many low-transition-temperature mixtures (LTTMs) have been investigated for this purpose. Among them, natural deep eutectic solvents (NADESs) have been proposed as cheap and renewable alternatives to ionic liquids for the synthesis of bio-based chemical building blocks. We compare herein the ability of several organic acids/choline chloride/water LTTMs to perform D-fructose dehydration to 5-hydroxymethylfurfural (5-HMF). The addition of chloride salts as well as an increased proportion of choline chloride promotes 5-HMF formation, which seems to indicate a beneficial effect of chloride anions on D-fructose dehydration. Besides improving selectivity by at least 10 %, increasing the choline chloride/acid ratio could enhance the biodegradability of the LTTMs. Unlike other acidic components, maleic and citric acids are especially selective at early D-fructose conversion. Maleic acid was the most selective acidic component among the tested chemicals, achieving an 80 % 5-HMF molar yield in 1 h at 90°C.

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

“…Of the 94 productso btained from these sugars, 25 were selected as involving feasible technologiest hat are suitablef or large-scale prototype testing in ap ilot plant. [11][12][13] Other research has focused on optimizingh eterogeneous catalysts for dehydration reactions involving both metal catalysts [14][15][16][17][18][19][20] and supported ionic liquids. [3] The main route to form HMF is by the dehydration of sugars, [4] and important resultsh ave been achieved for HMF production using ionic liquids.…”

“…[10] Deep eutectic solvents andw ater have also been investigated for the dehydration of fructose into HMF but improvedy ields are still needed. [11][12][13] Other research has focused on optimizingh eterogeneous catalysts for dehydration reactions involving both metal catalysts [14][15][16][17][18][19][20] and supported ionic liquids. [21,22] In particular, ionic liquidsw ith halide counteranions have provenv ery efficient for the production of HMF from fructose, glucose,a nd cellulose with both Brønsted and Lewis acid catalysts.…”

Monosaccharides Dehydration Assisted by Formation of Borate Esters of α-Hydroxyacids in Choline Chloride-Based Low Melting Mixtures

“…Compared to the preliminary experiments, the ratio between boric acid and the organic acid in LTTMs was rapidly optimized regarding 5-HMF yield. Considering the large number of organic acids under consideration, LTTMs were directly prepared in (Istasse et al, 2018). The same procedure was followed for the tests with benzoic acid derivatives.…”

“…In a preliminary experiment, several hexoses (D-fructose, Dglucose and D-mannose), and pentoses (D-xylose and Darabinose) were heated during 2 h in a mixture of choline chloride and maleic acid at 90 • C. Although maleic acid is known to efficiently dehydrate D-fructose to 5-HMF (Istasse et al, 2018), this attempt did not lead to the appearance of 5-HMF from Dglucose and D-mannose or 2-F from D-arabinose. Only 2.26 ± 0.04% of 2-F was generated from D-xylose.…”

“…This very simple synthesis process enables a 100% carbon efficiency (Zhang et al, 2012). Istasse et al (2018) demonstrated the efficiency of LTTM's composed of choline chloride and organic acids to perform Dfructose dehydration to 5-HMF at 60 • C. However, it is worth noting that even though the synthesis of furanic derivatives from ketoses (e.g., D-fructose, D-xylulose) is straightforward, their production from aldoses (e.g., D-glucose, D-xylose) remains challenging. Selective and low-cost dehydration process of those abundant hexoses has still to be developed (Rosatella et al, 2011;Van Putten et al, 2013b).…”