NMR characterization of sodium carboxymethyl cellulose 2: Chemical shift assignment and conformation analysis of substituent groups

作者：Kono Hiroyuki^*; Oshima Kazuhiro; Hashimoto Hisaho; Shimizu Yuuichi; Tajima Kenji

来源：Carbohydrate Polymers, 2016, 150: 241-249.

DOI：10.1016/j.carpol.2016.05.003

• Carboxymethyl cellulose
• Substituent distribution
• Conformation analysis
• Nuclear magnetic resonance

The chemical shifts of the substituent groups of sodium carboxymethyl cellulose (CMC) were assigned by examining a series of CMC samples with different degrees of substitution. Comparative analysis of the H-1-C-13 heteronuclear single quantum coherence (HSQC) and heteronuclear multiple bond correlation (HMBC) spectra allowed the complete assignment of the substituent groups at the 2-, 3-, and 6 -positions of the seven substituted monomers comprising the CMC chains, namely, 2 -mono-, 3 -mono-, 6-mono, 2,3 -di-, 2,6 -di-, 3,6 -di-, and 2,3,6-tri-substituted anhydroglucose units (AGUs). In addition, the mole fractions of the monomers were determined by lineshape analysis of the carbonyl carbon resonances. The comparison between the chemical shifts of the substituents revealed strong interactions between 2 and 3-substituents in the same AGU, and showed that the steric hindrance by a substituent at the 2- or 3-position suppresses subsequent substitution at the adjacent position.

• 出版日期2016-10-5