Solvent-Free Production of 5-Hydroxymethylfurfural from Deep Eutectic Substrate Reaction Mixtures over a Magnetically Recoverable Solid Acid Catalyst

A novel magnetically recoverable solid acid catalyst was synthesized by immobilization of sulfonic acid groups on triazine dendrimer-modified magnetic nanoparticles. The structure NW and composition of the synthesized catalyst were characterized by thermogravimetric analysis (TGA), elemental analysis, Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDX) spectroscopy, elemental mapping, acid-base titration, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). The catalytic performance of the catalyst was evaluated for the conversion of carbohydrates to 5-hydroxymethylfurfural (5-HMF) in various deep eutectic mixtures as neoteric green and environmentally benign reaction media. Among the 13 deep eutectic mixtures investigated, the mixture comprising equal moles of sucrose and fructose yielded the highest 5-HMF yield. No additional reaction solvent was necessary since the sucrose/fructose (1:1, mol/mol) system acted as a combined solvent and substrate for 5-HMF production. Thus, this catalyst system would open up a novel opportunity for the efficient production of 5-HMF under solvent-free conditions. Moreover, the catalyst could be simply separated from the reaction mixture by using a magnetic field and recycled up to five times without incredible loss in its activity.

Automated summary

A novel magnetically recoverable solid acid catalyst was synthesized by immobilizing sulfonic acid groups on triazine dendrimer-modified magnetic nanoparticles. The catalyst showed high efficiency in converting carbohydrates to 5-HMF in various deep eutectic mixtures as neoteric green and environmentally benign reaction media, and could be easily separated and recycled using a magnetic field.