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Article

Dissolving Cellulose in 1,2,3-Triazolium- and Imidazolium-Based Ionic Liquids with Aromatic Anions

Institut für Chemie, Martin-Luther-Universität Halle–Wittenberg, von-Danckelmann-Platz 4, D-06120 Halle, Germany
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Molecules 2020, 25(15), 3539; https://doi.org/10.3390/molecules25153539
Received: 10 July 2020 / Revised: 29 July 2020 / Accepted: 30 July 2020 / Published: 2 August 2020
(This article belongs to the Special Issue Ionic Liquids, from Their Synthesis to Their Applications)
We present 1,2,3-triazolium- and imidazolium-based ionic liquids (ILs) with aromatic anions as a new class of cellulose solvents. The two anions in our study, benzoate and salicylate, possess a lower basicity when compared to acetate and therefore should lead to a lower amount of N-heterocyclic carbenes (NHCs) in the ILs. We characterize their physicochemical properties and find that all of them are liquids at room temperature. By applying force field molecular dynamics (MD) simulations, we investigate the structure and dynamics of the liquids and find strong and long-lived hydrogen bonds, as well as significant ππ stacking between the aromatic anion and cation. Our ILs dissolve up to 8.5 wt.-% cellulose. Via NMR spectroscopy of the solution, we rule out chain degradation or derivatization, even after several weeks at elevated temperature. Based on our MD simulations, we estimate the enthalpy of solvation and derive a simple model for semi-quantitative prediction of cellulose solubility in ILs. With the help of Sankey diagrams, we illustrate the hydrogen bond network topology of the solutions, which is characterized by competing hydrogen bond donors and acceptors. The hydrogen bonds between cellulose and the anions possess average lifetimes in the nanosecond range, which is longer than found in common pure ILs. View Full-Text
Keywords: ionic liquids; cellulose; triazolium; solvent; carbenes; molecular dynamics; enthalpy of solvation; solubility prediction ionic liquids; cellulose; triazolium; solvent; carbenes; molecular dynamics; enthalpy of solvation; solubility prediction
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MDPI and ACS Style

Brehm, M.; Radicke, J.; Pulst, M.; Shaabani, F.; Sebastiani, D.; Kressler, J. Dissolving Cellulose in 1,2,3-Triazolium- and Imidazolium-Based Ionic Liquids with Aromatic Anions. Molecules 2020, 25, 3539. https://doi.org/10.3390/molecules25153539

AMA Style

Brehm M, Radicke J, Pulst M, Shaabani F, Sebastiani D, Kressler J. Dissolving Cellulose in 1,2,3-Triazolium- and Imidazolium-Based Ionic Liquids with Aromatic Anions. Molecules. 2020; 25(15):3539. https://doi.org/10.3390/molecules25153539

Chicago/Turabian Style

Brehm, Martin, Julian Radicke, Martin Pulst, Farzaneh Shaabani, Daniel Sebastiani, and Jörg Kressler. 2020. "Dissolving Cellulose in 1,2,3-Triazolium- and Imidazolium-Based Ionic Liquids with Aromatic Anions" Molecules 25, no. 15: 3539. https://doi.org/10.3390/molecules25153539

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