Volatility study of [C(1)C(1)im][NTf2] and [C(2)C(3)im][NTf2] ionic liquids
authors Rocha, MAA; Ribeiro, FMS; Schroder, B; Coutinho, JAP; Santos, LMNBF
nationality International
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.
publisher ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
issn 0021-9614
year published 2014
volume 68
beginning page 317
ending page 321
digital object identifier (doi) 10.1016/j.jct.2013.09.020
web of science category Thermodynamics; Chemistry, Physical
subject category Thermodynamics; Chemistry
unique article identifier WOS:000326271100041
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