Conversion of Glucose to 5-Hydroxymethylfurfural, Levulinic Acid, and Formic Acid in 1,3-Dibutyl-2-(2-butoxyphenyl)-4,5-diphenylimidazolium Iodide-Based Ionic Liquid

Abstract

The separation process between 5-hydroxymethylfurfural (HMF) and trace glucose in glucose conversion is important in the biphasic system (aqueous–organic phase), due to the partial solubility property of HMF in water. In addition, the yield of HMF via the dehydration reaction of glucose in water is low (under 50%) with the use of Brønsted acid as a catalyst. Therefore, this study was conducted to optimize the production and separation of products by using a new hydrophobic ionic liquid (IL), which is more selective than water. The new IL (1,3-dibutyl-2-(2-butoxyphenyl)-4,5-diphenyl imidazolium iodide) [DBDIm]I was used as a solvent and was optimized for the dehydration reaction of glucose to make a more selective separation of HMF, levulinic acid (LA), and formic acid (FA). [DBDIm]I showed high performance as a solvent for glucose conversion at 100 °C for 120 min, with a yield of 82.2% HMF, 14.9% LA, and 2.9% FA in the presence of sulfuric acid as the Brønsted acid catalyst.

Influence of the cation partner on levulinate ionic liquids properties

“…cellulose and hemicellulose, are also valuable sources of compounds for the development of bio-based ILs when converted into smaller molecules such as formic acid, acetic acid, levulinic acid, furfural and hydroxymethyl furfural. [33][34][35][36] While formate and acetate ILs have been known for more than twenty years, the utilization of the other mentioned platform chemicals for ILs preparation is far more recent. In particular, for furfural and hydroxymethyl furfural a very limited number of studies have been reported.…”

Direct Brønsted Acid-Catalyzed Dehydration of Glucose to HMF in Methyl Isobutyl Ketone

“…Scheme depicts the most predominant reaction mechanisms for Brønsted acid-catalyzed dehydration of glucose to HMF, including a direct dehydration pathway (B), as well as cyclic (A), and acyclic (C) mechanisms with the intermediate formation of fructose. Although extensive evidence supporting acyclic ,,− and cyclic ,,, pathways has been presented, it is generally agreed that the specific reaction mechanism is determined by the reaction conditions, particularly the choice of solvent. ,,, …”

Optimization Study of Glucose Synthesis to 5-Hydroxymethylfurfural (5-HMF) by Using Low Transition-Temperature Mixtures (LTTM)

“…Xiang et al reported that the production of 5-HMF using only water as the solvent did not significantly improve the conversion of glucose to 5-HMF. Dehydrating agents such as Lewis acid or Brønsted acid sites are required to promote sugar dehydration to 5-HMF [42].…”