Hydrogen bond formation in regioselectively functionalized 3-mono-O-methyl cellulose.
The hydrogen bond systems of cellulose and its derivatives are one of the most important factors regarding their physical- and chemical properties such as solubility, crystallinity, gel formation, and resistance to enzymatic degradation. In this paper, it was attempted to clarify the intra- and intermolecular hydrogen bond formation in regioselectively functionalized 3-mono-O-methyl cellulose (3MC). First, the 3MC was synthesized and the cast film thereof was characterized in comparison to 2,3-di-O-methyl cellulose, 6-mono-O-methyl cellulose, and 2,3,6-tri-O-methyl cellulose by means of wide angle X-ray diffraction (WAXD) and (13)C cross polarization/magic angle spinning NMR spectroscopy. Second, the hydrogen bonds in the 3MC film were analyzed by means of FTIR spectroscopy in combination with a curve fitting method. After deconvolution, the resulting two main bands (Fig. 3) indicated that instead of intramolecular hydrogen bonds between position OH-3 and O-5 another intramolecular hydrogen bond between OH-2 and OH-6 may exist. The large deconvoluted band at 3340cm(-1) referred to strong interchain hydrogen bonds involving the hydroxyl groups at C-6. The crystallinity of 54% calculated from the WAXD supports also the dependency of the usually observed crystallization in cellulose of the hydroxyl groups at C-6 to engage in interchain hydrogen bonding.
Kondo
Tetsuo
T
Bio-Architecture Center and Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan. tekondo@agr.kyushu-u.ac.jp
Koschella
Andreas
A
Heublein
Brigitte
B
Klemm
Dieter
D
Heinze
Thomas
T
D002482:Cellulose / Q000737:chemistry; D003460:Crystallization; D003461:Crystallography; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008747:Methylcellulose / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014961:X-Ray Diffraction
D002482:Cellulose; D008747:Methylcellulose