A simple and efficient synthesis of 5-hydroxymethylfurfural from carbohydrates using acidic ionic liquid grafted on silica gel

The catalytic application of 3-(4-sulfobutyl)-1H-imidazole-3-ium chloride immobilized on activated silica gel (SiO2-Imi-SO3H) for the production of 5-hydroxymethylfurfural is described here for the first time. This material was synthesized using a three-step method involving the grafting of chloropropyl groups onto activated silica gel, the substitution of zwitterions, and the acidification of zwitterions to form silica-supported ionic liquid. The successful immobilization of the IL on silica gel was confirmed through energy-dispersive X-ray (EDX) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and elemental mapping. SiO2-Imi-SO3H-2 demonstrated good catalytic activity and recycling ability in fructose dehydration to 5-HMF. Several conditions for reaction were investigated, and an excellent 5-HMF yield (94.1%) was obtained after 4 h at 160 °C in dimethyl sulfoxide (DMSO) from fructose. Furthermore, a mechanism was proposed, the catalyst's reusability was investigated, and the catalyst was applied for the conversion of glucose to 5-HMF with other metal salts.