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

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• 作者：Hiroyuki Kono^a ; ^{kono@tomakomai-ct.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Kazuhiro Oshima^a ; Hisaho Hashimoto^a ; Yuuichi Shimizu^a ; Kenji Tajima^b
• 关键词：2D ; two-dimensional ; AGU ; anhydroglucose unit ; CMC ; carboxymethyl cellulose ; COSY ; correlation spectroscopy ; DS ; substitution degree ; DSS ; 4 ; 4-dimethyl-4-silapentane-1-sulfonic acid ; HMBC ; heteronuclear multiple-bond correlation ; HSQC ; heteronuclear single quantum coherence ; HB ; hydrogen bond ; CC ; carbonyl carbon ; MC ; methylene carbon
• 刊名：Carbohydrate Polymers
• 出版年：2016
• 出版时间：5 October 2016
• 年：2016
• 卷：150
• 期：Complete
• 页码：241-249
• 全文大小：2853 K

文摘

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 ¹H–¹³C 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.