Chinese Journal of Magnetic Resonance ›› 2026, Vol. 43 ›› Issue (2): 146-163.doi: 10.11938/cjmr20253182cstr: 32225.14.cjmr20253182

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NMR Study of Tautomeric Distribution of Monosaccharides in Imidazolyl Ionic Liquids/DMSO-d6

LIU Jia1, WANG Yingxiong1,*(), ZHAO Jiancheng2,#()   

  1. 1 College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
    2 Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China
  • Received:2025-09-23 Published:2026-06-05 Online:2025-12-10
  • Contact: WANG Yingxiong, ZHAO Jiancheng E-mail:wangyingxiong@tyut.edu.cn;zhaojiancheng@sxicc.ac.cn

Abstract:

The tautomeric distribution of monosaccharides could influence reaction pathways and product selectivity during their conversion and utilization. Using DMSO-d6 as cosolvent, we investigated the tautomeric distribution of monosaccharides in imidazolyl ionic liquids at 25 ℃ by quantitative 1H NMR. In acidic ionic liquids, the results indicate that the proportion of β-pyranose after equilibrium decreases in the following order: D-glucose > D-glucosamine hydrochloride > N-acetyl-D-glucosamine > D-mannose. D-fructose is almost completely converted to 5-hydroxymethylfurfural (formed from the furanose) in [HSO3-BMIM]HSO4. In other ionic liquids, the proportion of furanose even exceeds that of pyranose after equilibrium. The introduction of amphoteric metal chloride and fluorine may lead to a higher proportion of furanose. The addition of [BMIM]BF4 and other reagents may inhibit the tautomeric conversion of monosaccharides. The fundamental data on monosaccharide tautomer distribution can guide the selection and design of ionic liquids for biomass conversion.

Key words: monosaccharides, imidazolyl ionic liquids, NMR, tautomeric distribution

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