Extractive Promotion on the Synthesis of 5‐Hydroxymethylfurfural from Highly Concentrated Saccharides in Ionic Liquid

Abstract

Abstract5‐Hydroxymethylfurfural (5‐HMF) is perceived as a versatile biobased platform compound. The large‐scale production of 5‐HMF in ionic liquids (ILs) is still limited due to the inefficiency with diluted carbohydrate feedstocks. The IL/extractant biphasic media are benign systems for the efficient synthesis of 5‐HMF from highly concentrated carbohydrates. This work demonstrated that the hydrogen‐bond interaction between the hydroxyl group of 5‐HMF and IL played a critical role in the dissolution of 5‐HMF. The introduction of hydroxyl group into the structure of an IL was conducive to break the mentioned hydrogen‐bond interaction, therefore improving the extraction of 5‐HMF. Ethyl levulinate (EL) was found to be an excellent extractant for separating 5‐HMF from ILs for the first time. In a system consisting of 1‐hydroxyethyl‐3‐methylimidazolium chloride, EL and water, highly concentrated (80 wt %) fructose and glucose could be efficiently converted into 5‐HMF with a yield of 82 % and 70 % at 100 °C and 120 °C, respectively. The obtained results are superior to previous works on the synthesis of 5‐HMF from highly concentrated carbohydrates, which can provide useful information on designing a process for the large‐scale refining of biomass in ILs.