Are Alkylsulfates-based Protic and Aprotic Ionic Liquids Stable with Water and Alcohols? A Thermodynamic Approach
Jacquemin, J; Goodrich, P; Jiang, W; Rooney, DW; Hardacre, C
| HERO ID | 1454306 |
|---|---|
| In Press | No |
| Year | 2013 |
| Title | Are Alkylsulfates-based Protic and Aprotic Ionic Liquids Stable with Water and Alcohols? A Thermodynamic Approach |
| Authors | Jacquemin, J; Goodrich, P; Jiang, W; Rooney, DW; Hardacre, C |
| Journal | Journal of Physical Chemistry B |
| Volume | 117 |
| Issue | 6 |
| Page Numbers | 1938-1949 |
| Abstract | The knowledge of the chemical stability as a function of the temperature of ionic liquids (ILs) in the presence of other molecules such as water is crucial prior to developing any industrial application and process involving these novel materials. Fluid phase equilibria and density over large range of temperature and composition can give basic information on IL purity and chemical stability. The IL scientific community requires accurate measurements accessed from reference data. In this work, the stability of different alkylsulfates-based ILs in the presence of water and various alcohols (methanol, ethanol, 1-butanol and 1-octanol) was investigated to understand their stability as a function of temperature up to 423.15 K over the hydrolysis and transesterification reactions, respectively. From this investigation, it was clear that methylsulfate- and ethylsulfate- based ILs are not stable in presence of water since hydrolysis of the methylsulfate or ethylsulfate anions to methanol or ethanol and hydrogenate anion is undoubtedly observed. Such observations could help explain the differences observed for the physical properties published in the literature by various groups. Furthermore, it appears that a thermodynamic equilibrium process drives these hydrolysis reactions. In other words, these hydrolysis reactions are in fact reversible, providing the possibility to reform the desired alkylsulfate anions by a simple transesterification reaction between hydrogen sulfate-based ILs and the corresponding alcohol (methanol or ethanol). Additionally, butylsulfate and octylsulfate-based ILs appear to follow this pattern but under more drastic conditions. In these systems hydrolysis is observed in both cases after several months for temperature up to 423 K in presence of water. Therein, the partial miscibility of hydrogen sulfate-based ILs with long chain alcohols (1-butanol and 1-octanol) can help explain the enhanced hydrolytic stability of the butylsulfate- and octylsulfate-based ILs compared with the methyl- or ethysulfate systems. Additionally, rapid transesterification reactions are observed during liquid-liquid equilibrium studies as a function of temperature for binary systems of (hydrogen sulfate-based ionic liquids + 1-butanol) and of (hydrogen sulfate-based ionic liquids + 1-octanol). Finally, this atom efficient catalyst-free transesterification reaction between hydrogen sulfate -based ILs and alcohol was then tested to provide a novel way to synthesize new ILs with various anion structures containing the alkylsulfate group. |
| Doi | 10.1021/jp312241h |
| Pmid | 23320846 |
| Wosid | WOS:000315181600054 |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |
| Language Text | English |