|
authors |
Rocha, MAA; Ribeiro, FMS; Schroder, B; Coutinho, JAP; Santos, LMNBF |
|
nationality |
International |
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journal |
JOURNAL OF CHEMICAL THERMODYNAMICS |
|
author keywords |
Volatility; Ionic liquids; Vapor pressure; Thermodynamics; Entropy; Enthalpy; Vaporization; Knudsen effusion; 1-Ethyl-3-propylimidazolium; 1,3-Dimethylimidazolium; Bis(trifluoromethylsulfonyl)imide |
|
keywords |
THERMODYNAMIC PROPERTIES; CONFORMATIONS; CONSTANTS |
|
abstract |
Vapor pressures of 1,3-dimethylimidazolium bis(trifluoromethylsulfonyl) imide, ([C(1)C(1)im][NTf2]) and 1ethyl-3-propylimidazolium bis(trifluoromethylsulfonyl) imide, ([C(2)C(3)im][NTf2]) ionic liquids were measured as a function of temperature using a Knudsen effusion apparatus combined with a quartz crystal microbalance. Enthalpies and entropies of vaporization were derived from the fitting of vapor pressure and temperature results to the Clarke and Glew equation. [C(1)C(1)im][NTf2] presents a higher enthalpy and entropy of vaporization than the neighboring members of the series. The enthalpy of vaporization of [C(2)C(3)im][NTf2] lies in between the asymmetric and symmetric ionic liquid series, reflecting a decrease in the electrostatic interactions due to a decrease of the charge accessibility between the ionic pairs when the methyl group is replaced by an ethyl group. The obtained higher volatility of [C(2)C(3)im][NTf2] arises from its asymmetric character, leading to an higher entropic contribution that compensates the enthalpic penalty. The border conditions ([C(1)C(1)im][NTf2], [C(2)C(1)im][NTf2] and [C(2)C(2)im][NTf2]), topology ([C(2)C(3)im][NTf2]) and symmetry/asymmetry of the ILs effect were evaluated and rationalized based on a comparative analysis of the thermodynamic properties, enthalpies and entropies of vaporization. (C) 2013 Elsevier Ltd. All rights reserved. |
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publisher |
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD |
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issn |
0021-9614 |
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year published |
2014 |
|
volume |
68 |
|
beginning page |
317 |
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ending page |
321 |
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digital object identifier (doi) |
10.1016/j.jct.2013.09.020 |
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web of science category |
Thermodynamics; Chemistry, Physical |
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subject category |
Thermodynamics; Chemistry |
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unique article identifier |
WOS:000326271100041
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