AUTHOR=Huang Ting , Yuan Kun , Nie Xu-Liang , Chen Jing , Zhang Huang-Xian , Chen Jin-Zhu , Xiong Wan-Ming 

TITLE=Preparation of Furfural From Xylose Catalyzed by Diimidazole Hexafluorophosphate in Microwave

JOURNAL=Frontiers in Chemistry

VOLUME=Volume 9 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2021.727382

DOI=10.3389/fchem.2021.727382

ISSN=2296-2646

ABSTRACT=In this work, functionalized alkyl imidazolium hexafluorophosphate ILs were synthesized and characterized, and then they were applied in the conversion of xylose to furfural under the microwave. The results showed that when CnMF was used as a catalyst, an acidic environment was provided to promote the formation of furfural. In addition, not only the heating method and the solvent, but also the different structurally of cations in the ionic liquid had an influence on their catalytic activity. In aqueous solution, the yield of furfural obtained under microwave was better than conventional heating method, and the catalytic activity of diimidazole hexafluorophosphate was better than that of monoimidazole. Meanwhile, for the diimidazole hexafluorophosphate, the change of the carbon chain length between the imidazole rings also had a slight influence on the yield. Finally, the optimal yield of 49.76% was obtained at 205℃ for 8 minutes using (3,3'-methylenebis(1-methyl-1H-imidazol-3-ium), C1MF) as catalyst. Mechanistic studies suggested that the catalytic activity of C1MF was mainly due to the combined effect of POFn (OH)3-n and imidazole ring. Without a doubt, the catalytic activity of C1MF was still available after five cycles, which not only showed its excellent catalytic activity in catalyzing the xylose to prepare the biomass platform compound furfural, but also could promote the application of functionalized ionic liquids.