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|Title:||Volatility study of [C(1)C(1)im][NTf2] and [C(2)C(3)im][NTf2] ionic liquids|
|Author:||Rocha, Marisa A. A.|
Ribeiro, Filipe M. S.
Coutinho, Joao A. P.
Santos, Luis M. N. B. F.
|Publisher:||ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD|
|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.|
|Appears in Collections:||CICECO - Artigos|
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|Volatility study of [C1C1im][NTf2] and [C2C3im][NTf2] ionic liquids_10.1016j.jct.2013.09.020.pdf||244.05 kB||Adobe PDF|
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