Preparation of 1,8-diazabicyclo[5.4.0]undecenium ionic liquid-bearing magnetic material as a catalyst for the conversion of xylose to furfural

Abstract

Nowadays, the conversion of carbohydrate compounds into furan heterocycles is one of the new trends in organic synthesis. However, a key concern is the use of homogeneous catalysts, which are challenging to recover and reuse, and pose environmental toxicity risks. This study aims to synthesize magnetic solid catalyst materials with good catalytic activity in the conversion of xylose into furfural. In this study, magnetic ionic liquid material was synthesized by immobilizing 1,8-diazabicyclo[5.4.0]undec-7-ene ionic liquid on the surface of Fe₃O₄ nanoparticles. Bronsted acid (-SO₃H) and Lewis acid (Cu_xCl_y^-) sites were modified on this material and applied as catalysts for the synthesis of furfural from xylose. The structure and properties of Fe₃O₄@SiO₂@(CH₂)₃@DBU-SO₃H-Cu_xCl_y material was determined by FT-IR, XRD, TGA, SEM and EDX. Various parameters in this chemical reaction, including the catalyst, catalyst amount, solvent, solvent volume, reaction temperature, and reaction time, which influenced the efficiency of furfural formation, were investigated. When the reaction was carried out with xylose (150 mg) in the presence of Fe₃O₄@SiO₂@(CH₂)₃@DBU-SO₃H-Cu_xCl_y catalyst (25 mg) and DMSO solvent (3 mL) at 150 °C for 6 hours, the reaction yield was recorded as 60.47%. Furfural was isolated by column chromatography, and its structure was confirmed by nuclear magnetic resonance spectroscopy (¹H and ¹³C NMR). The Fe₃O₄@SiO₂@(CH₂)₃@DBU-SO₃H-Cu_xCl_y catalyst could be recovered and reused three times without significantly changing the catalytic activity and original structure. This is a green, simple, safe, and environmentally friendly method for the conversion of xylose to furfural.