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 B 0 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.
Similar content being viewed by others
References
Bennett AE, Rienstra CM, Auger M, Lakshmi KV, Griffin RG (1995) Heteronuclear decoupling in rotating solids. J Chem Phys 103:6951–6958. doi:https://doi.org/10.1063/1.470372
Karakawa M, Mikawa Y, Kamitakahara H, Nakatsubo F (2002) Preparations of regioselectively methylated cellulose acetates and their 1H and 13C NMR spectroscopic analyses. J Polym Sci A Polym Chem 40:4167–4179. doi:https://doi.org/10.1002/pola.10498
Karrasch A, Jäger C, Karakawa M, Nakatsubo F, Potthast A, Rosenau T (2009) Solid-state NMR studies of methyl celluloses. Part 1: regioselectively substituted celluloses as standards for establishing an NMR data basis. Cellulose 16:129–137. doi:https://doi.org/10.1007/s10570-008-9247-z
Massiot D, Fayon F, Capron M, King I, LeCalvé S, Alonso B, Durand J-O, Bujoli B, Gan Z, Hoatson G (2002) Modelling one- and two-dimensional solid-state NMR spectra. Magn Reson Chem 40:70–76. doi:https://doi.org/10.1002/mrc.984
Metz G, Wu XL, Smith SO (1994) Ramped-amplitude cross-polarization in magic-angle-spinning NMR. J Magn Reson A 110:219–227. doi:https://doi.org/10.1006/jmra.1994.1208
Saake B, Lebioda S, Puls J (2004) Analysis of the substituent distribution along the chain of water-soluble methyl cellulose by combination of enzymatic and chemical methods. Holzforschung 58:97–104. doi:https://doi.org/10.1515/HF.2004.013
Ullmann’s Encyclopedia of Industrial Chemistry (2009) John Wiley, Weinheim
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.
Author information
Authors and Affiliations
Corresponding authors
Rights and permissions
About this article
Cite this article
Karrasch, A., Jäger, C., Saake, B. et al. 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. Cellulose 16, 1159–1166 (2009). https://doi.org/10.1007/s10570-009-9304-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10570-009-9304-2