Abstract
High-molecular-weight celluloses (which even include bacterial cellulose) can be dissolved fully in methyltrioctylphosphonium acetate/[D6]DMSO solutions to allow the measurement of resonance-overlap-free 1 D and 2 D NMR spectra. This is achieved by a simple and non-destructive dissolution method, without solvent suppression, pre-treatment or deuteration of the ionic component. We studied a range of cellulose samples by using various NMR experiments to make an a priori assignment of the cellulose resonances. Chain-end resonances are also visible in the 1H NMR spectrum. This allows the rough determination of the degree of polymerisation (DP) of a sample for low-DP celluloses by the integration of non-reducing chain ends C1 versus polymeric cellobiose C1. Low-DP celluloses show a good agreement with the gel-permeation chromatography (GPC) values, but high-DP pulps show more deviation. For high-purity pulps (pre-hydrolysis kraft and sulfite), residual xyloses and mannoses can also be identified from the 1H-13C heteronuclear single-quantum coherence (HSQC) spectra. Resonances are thus assigned for the common polymeric polysaccharides found in chemical pulps.
| Original language | English |
|---|---|
| Pages (from-to) | 880-892 |
| Number of pages | 13 |
| Journal | ChemSusChem |
| Volume | 9 |
| Issue number | 8 |
| DOIs | |
| Publication status | Published - 21 Apr 2016 |
| MoE publication type | A1 Journal article-refereed |
Funding
We would like to acknowledge CLIC Innovation for funding under the Advanced Cellulose to Novel Products (ACel) program. We would also like to thank Shirin Asaadi for the cotton samples, Stefan Willf?r for the spruce GGM samples and Agnes Stepan for the glucuronoxylan samples.
Keywords
- biomass
- carbohydrates
- ionic liquids
- nmr spectroscopy
- polymerization