Symmetrical and unsymmetrical Brønsted acidic ionic liquids for the effective conversion of fructose to 5-hydroxymethyl furfural

Abstract

Symmetrical and unsymmetrical Brønsted acidic Ionic Liquids (ILs) have been synthesized via a one-pot halogen-free route and characterized by TGA-DTA and DSC to compare their stability and activity. The acidities of the four ILs have also been tested by the Hammett method. These ILs were utilised as catalysts for the dehydration of fructose to 5-hydroxymethylfurfural (HMF) in the presence of dimethylsulphoxide (DMSO) as solvent. The effects of reaction time, temperature and catalyst concentration were studied. The ILs are very efficient for the reaction at relatively lower temperature with very good HMF yield and selectivities. The used ILs could be easily recycled without any significant loss in fructose conversion and HMF yield.