Physicochemical properties of N-alkylpyridine trifluoroacetate ionic liquids [CnPy][TFA] (n = 2–6). (April 2021)

• Record Type: Journal Article
• Authors: Song, Zongren; Yan, Qiang; Xia, Meichen; Qi, Xiaochen; Zhang, Zhiheng; Wei, Jie; Fang, Dawei; Ma, Xiaoxue
• Is Part Of: Journal of chemical thermodynamics. Volume 155(2021)
• Publication Date: 2021-04
• Subjects: N-alkylpyridine trifluoroacetate ionic liquids -- Density -- Surface tension -- Molar surface Gibbs energy -- Polarity; Thermodynamics -- Periodicals; Thermochemistry -- Periodicals; Thermodynamique -- Périodiques; Thermochimie -- Périodiques; Thermochemistry; Thermodynamics; Periodicals; 541.369
• DOI: 10.1016/j.jct.2020.106366
• Languages: English
• ISSNs: 0021-9614

Abstract

Highlights: [C n Py][TFA] ( n = 2–6) were synthesized and confirmed. The physicochemical properties were determined by SAM. Volume and surface properties were estimated by semi empirical. The molar surface Gibbs energy of interstice is proposed. Surface tension could be estimated by g s . Abstract: Series of N-alkylpyridine trifluoroacetate ionic liquids [C n Py][TFA] ( n = 2–6) were designed and synthesized by the neutralization method and characterized by 1 H NMR and DSC. The density, surface tension, and refractive index of [C n Py][TFA] ( n = 2–6) with different mass fraction of water were measured by standard addition method (SAM) at (293.15–343.15) K and the respective properties for the anhydrous [C n Py][TFA] ( n = 2–6) were calculated on the basis experimental data. The molecular volume V m, the standard entropy S 0 (298), the crystal energy U POT, the surface entropy S a, the surface energy E a of ionic liquid [C n Py][TFA] ( n = 2–6) were calculated. The enthalpy of vaporization at 298.15 K were estimated according to the Kabo's and Rebelo's empirical equation, and the traditional Eötvös equations were modified based on the calculated molar surface Gibbs energy, and its coefficients have clear physical meaning. The thermal expansion was estimated by the classical interstitial theory. At the same time, the classical interstitial theory has been improved and the molar surface Gibbs energy of interstice was proposed. In addition, surface tension could be estimated by the molar surface Gibbs energy, and the estimated values were highly correlated with the experimental ones. Finally, the concept of solubility parameter was introduced, which can be used to estimate the polarity of ionic liquids and it was consistent with our experience.