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Ionization of Cellobiose in Aqueous Alkali and the Mechanism of Cellulose Dissolution

Bialik, Erik LU ; Stenqvist, Björn LU ; Fang, Yuan; Östlund, Åsa; Furó, István; Lindman, Björn LU ; Lund, Mikael LU and Bernin, Diana (2016) In The Journal of Physical Chemistry Letters 7(24). p.5044-5048
Abstract

Cellulose, one of the most abundant renewable resources, is insoluble in most common solvents but dissolves in aqueous alkali under a narrow range of conditions. To elucidate the solubilization mechanism, we performed electrophoretic NMR on cellobiose, a subunit of cellulose, showing that cellobiose acts as an acid with two dissociation steps at pH 12 and 13.5. Chemical shift differences between cellobiose in NaOH and NaCl were estimated using 2D NMR and compared to DFT shift differences upon deprotonation. The dissociation steps are the deprotonation of the hemiacetal OH group and the deprotonation of one of four OH groups on the nonreducing anhydroglucose unit. MD simulations reveal that aggregation is suppressed upon charging... (More)

Cellulose, one of the most abundant renewable resources, is insoluble in most common solvents but dissolves in aqueous alkali under a narrow range of conditions. To elucidate the solubilization mechanism, we performed electrophoretic NMR on cellobiose, a subunit of cellulose, showing that cellobiose acts as an acid with two dissociation steps at pH 12 and 13.5. Chemical shift differences between cellobiose in NaOH and NaCl were estimated using 2D NMR and compared to DFT shift differences upon deprotonation. The dissociation steps are the deprotonation of the hemiacetal OH group and the deprotonation of one of four OH groups on the nonreducing anhydroglucose unit. MD simulations reveal that aggregation is suppressed upon charging cellulose chains in solution. Our findings strongly suggest that cellulose is to a large extent charged in concentrated aqueous alkali, a seemingly crucial factor for solubilization. This insight, overlooked in the current literature, is important for understanding cellulose dissolution and for synthesis of new sustainable materials.

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organization
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Contribution to journal
publication status
published
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in
The Journal of Physical Chemistry Letters
volume
7
issue
24
pages
5 pages
publisher
The American Chemical Society
external identifiers
  • scopus:85006725083
  • wos:000390087000014
ISSN
1948-7185
DOI
10.1021/acs.jpclett.6b02346
language
English
LU publication?
yes
id
8e3d9748-5fd0-4a76-a80f-ef11efef3fbc
date added to LUP
2017-01-11 13:30:39
date last changed
2017-11-12 04:27:56
@article{8e3d9748-5fd0-4a76-a80f-ef11efef3fbc,
  abstract     = {<p>Cellulose, one of the most abundant renewable resources, is insoluble in most common solvents but dissolves in aqueous alkali under a narrow range of conditions. To elucidate the solubilization mechanism, we performed electrophoretic NMR on cellobiose, a subunit of cellulose, showing that cellobiose acts as an acid with two dissociation steps at pH 12 and 13.5. Chemical shift differences between cellobiose in NaOH and NaCl were estimated using 2D NMR and compared to DFT shift differences upon deprotonation. The dissociation steps are the deprotonation of the hemiacetal OH group and the deprotonation of one of four OH groups on the nonreducing anhydroglucose unit. MD simulations reveal that aggregation is suppressed upon charging cellulose chains in solution. Our findings strongly suggest that cellulose is to a large extent charged in concentrated aqueous alkali, a seemingly crucial factor for solubilization. This insight, overlooked in the current literature, is important for understanding cellulose dissolution and for synthesis of new sustainable materials.</p>},
  author       = {Bialik, Erik and Stenqvist, Björn and Fang, Yuan and Östlund, Åsa and Furó, István and Lindman, Björn and Lund, Mikael and Bernin, Diana},
  issn         = {1948-7185},
  language     = {eng},
  month        = {12},
  number       = {24},
  pages        = {5044--5048},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Letters},
  title        = {Ionization of Cellobiose in Aqueous Alkali and the Mechanism of Cellulose Dissolution},
  url          = {http://dx.doi.org/10.1021/acs.jpclett.6b02346},
  volume       = {7},
  year         = {2016},
}