NMR characterization of sodium carboxymethyl cellulose 2: Chemical shift assignment and conformation analysis of substituent groups.
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 (1)H-(13)C 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.
National Institute of Technology, Tomakomai College, Nishikioka 443, Tomakomai, Hokkaido 059 1275, Japan. Electronic address: kono@tomakomai-ct.ac.jp.
Hiroyuki
H
Kono
National Institute of Technology, Tomakomai College, Nishikioka 443, Tomakomai, Hokkaido 059 1275, Japan.
Kazuhiro
K
Oshima
National Institute of Technology, Tomakomai College, Nishikioka 443, Tomakomai, Hokkaido 059 1275, Japan.
Hisaho
H
Hashimoto
National Institute of Technology, Tomakomai College, Nishikioka 443, Tomakomai, Hokkaido 059 1275, Japan.
Yuuichi
Y
Shimizu
Faculty of Engineering, Hokkaido University, N13W8, Kita-ku, Sapporo 060 8628, Japan.
Kenji
K
Tajima
D002236:Carbohydrate Conformation; D002266:Carboxymethylcellulose Sodium / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy
D005947:Glucose; D002266:Carboxymethylcellulose Sodium
Carboxymethyl cellulose; Conformation analysis; Nuclear magnetic resonance; Substituent distribution