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Cellulose

, Volume 16, Issue 6, pp 1159–1166 | Cite as

Solid-state NMR studies of methyl celluloses. Part 2: Determination of degree of substitution and O-6 vs. O-2/O-3 substituent distribution in commercial methyl cellulose samples

  • Andrea Karrasch
  • Christian JägerEmail author
  • Bodo Saake
  • Antje Potthast
  • Thomas RosenauEmail author
Article

Abstract

Solid state NMR spectroscopy was applied to determine the overall degree of substitution (DS) and the degrees of substitution at C-6 (DSC-6) and C-2/3 (DSC-2/3). Four commercial methyl cellulose samples were used, having a DS between 0.51 and 1.96 as determined by wet-chemical analysis. The strategy and optimization of the NMR data acquisition as well as the data evaluation procedures are explained in detail. Optimization of the approach mainly comprised (a) maximizing the signal by choice of NMR probe, MAS spinning frequency and B0 field, (b) minimizing the measurement time by a Torchia-type experiment and (c) suppressing probe background by rotor-synchronized echo detection. Data evaluation used simply the integration of three different spectral ranges in the 13C NMR spectrum. The results of the experiments were in good agreement with the wet-chemical data. The NMR approach takes about the same analysis time as the conventional hydrolysis/chromatography analysis. However, it is a generally applicable and simple alternative without need for an extended sample preparation which is most useful if wet-chemical/chromatographic analyses are undesired or unavailable. Further studies have to concentrate on the validation of the analytical method and application to a larger sample array.

Keywords

Methyl cellulose Solid-state NMR 13C CPMAS NMR Rotor-synchronized echo sequence Substituent distribution Substitution pattern Degree of substitution 

Notes

Acknowledgments

The financial support of the Austrian Fonds zur Förderung der wissenschaftlichen Forschung, project P-17426, and of the Austrian Christian-Doppler-Forschungsgesellschaft (CD lab “Advanced cellulose chemistry and analytics”) is gratefully acknowledged.

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Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  1. 1.BAM Federal Institute for Materials Research and TestingBerlinGermany
  2. 2.Institute for Wood Chemistry and Chemical Technology of WoodFederal Research Centre for Forestry and Forest ProductsHamburgGermany
  3. 3.Department of ChemistryUniversity of Natural Resources and Applied Life Sciences Vienna (BOKU)ViennaAustria

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