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.