Continuous‐Flow Synthesis of 5‐Hydroxymethylfurfural, Furfural from Monosaccharides: A Simple, Fast, and Practical Method

Abstract

5-Hydroxymethylfurfural (HMF), a versatile intermediate from biomass, can be applied to prepare a wide range of valuable compounds in the petroleum and chemical industries. Thus, simple, fast, and practical methods to convert carbohydrates into HMF have been capturing increasing attention. We reported herein a method of using p-toluenesulfonic acid (p-TsOH) and Brønsted acidic ionic liquid as catalysts for the dehydration of fructose in dimethyl sulfoxide (DMSO) under a continuous flow process. The effect of the various reaction conditions on HMF formation was investigated, and the HMF yields were determined by the HPLC method. The results showed that p-TsOH and Brønsted acidic ionic liquid are effective catalysts within short residence times. This study provides a simple and safe procedure that can be potentially performed on a large scale to synthesize HMF from fructose.

Eco-Friendly Synthesis of 5-Hydroxymethylfurfural and Its Applications as a Starting Material to Synthesize Valuable Heterocyclic Compounds

“…The HMF yield is improved significantly up to 98% in only 10 min when the dehydration of fructose is carried out at 100 °C. However, at high temperatures, the dark-colored reaction mixture was observed during the reaction, presumably due to the formation of humins via polymerization. ,, …”

“…However, at high temperatures, the darkcolored reaction mixture was observed during the reaction, presumably due to the formation of humins via polymerization. 50,72,73 3. After the reaction was completed, the mixture was cooled in an ice bath and extracted several times with ethyl acetate/diethyl ether until HMF was not presented in an organic solvent (checked by TLC).…”

Microflow chemistry and its electrification for sustainable chemical manufacturing

“…Upon increasing the reaction temperature to 150 °C, 99% fructose conversion and 99% HMF yield were achieved at = 6 min. 125 McNeff et al demonstrated 13% HMF yield using TiO 2 and 1:1 water:n-BuOH extraction at 200 °C at RS 3 min.126 Despite the low HMF yield, the short contact time and high fructose concentration (23%) mark high productivity. An HMF yield of 29% was obtained at 180 °C at = 2 min and was further increased to 37% by adding 0.15 M HCl co-catalyst127 using a larger organic solvent usage (1:10 water:MIBK) instead of the 1:1 water:n-BuOH.…”

“…For example, in DMSO, the furanose increases from 20% to 72.3% at room temperature [121][122][123] to 89.4% at 150 C. 121 It is no surprise that DMSO is oen used as a co-solvent or solvent. 52,124 Ly et al described a single-phase DMSO continuous system utilizing Brønsted acidic imidazolium-based ionic liquid ([BMIMSO 3 H][HSO 4 ]) catalyst giving a 46% HMF yield at 130 C. 125 However, DMSO is a "yellow" solvent due to its high boiling point and poor incineration score. 126 Other organic solvents, such as acetone (greener on the solvent selection scale 126 ), also improve HMF yield due to the mutarotation enhancement.…”

The Role Played by Ionic Liquids in Carbohydrates Conversion into 5-Hydroxymethylfurfural: A Recent Overview

“…Fructose conversion into 5-HMF was also performed in flow conditions, by using as catalyst, the Brønsted acidic ionic liquid [bmimSO 3 H][HSO 4 ] [ 45 ]. The process was performed at 130 °C and the best yield in 5-HMF (55%) was obtained in 45 s of residence time.…”