Dual Brønsted-Functionalized Ionic Liquid for Efficient Dehydration of Fructose into 5-Hydroxymethylfurfural in MIBK/H ₂ O as a Biphasic System

5-Hydroxymethylfurfural (HMF) is a fundamental compound for deriving fuels and chemicals from renewable biomass. This study employed a biphasic system comprising an aqueous reaction phase (saturated NaCl) and an organic extraction phase (methyl isobutyl ketone, MIBK), utilizing dual acidic ionic liquid catalysts to promote fructose dehydration to HMF. This approach facilitated the desired product separation under mild conditions, offering a sustainable and green strategy for the practical application of HMF production on an industrial scale. Various reaction conditions were comprehensively investigated to optimize the yield of the HMF. A good HMF yield of 85% was obtained from fructose conversion with a dual Brønsted-functionalized ionic liquid [DBU-SO3H][TsO] in the water (NaCl):MIBK (1:3) biphasic solution at a mild temperature of 120 °C for a short time of 60 min. The catalyst also demonstrated good stability in thermogravimetric analysis and reusability performance.