Density, Thermal Expansion and Viscosity of Cholinium‐Derived Ionic Liquids

Abstract

Density and viscosity data of the N-alkyl-N,N-dimethyl-N-(2-hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide ionic liquids homologous series [N(1 1 n 2(OH))][Ntf(2)] with n=1, 2, 3, 4 and 5 have been measured at atmospheric pressure in the 283<T/K<373 temperature range and the corresponding isobaric thermal expansion coefficients have been calculated. This work studies the effect of increasing the alkyl chain length of the cholinium-based cation on the density, viscosity and related properties of this family of ionic liquids. A volumetric predictive method based on the effective molar volume of cations and anions is used to estimate the effective molar volume of the different cations present in this study. The results agree with data for other cation families that show a molar volume increment per CH(2) group on the alkyl chain of the cation of about 17.2 cm(3) mol(-1), except for [N(1 1 1 2(OH))](+), which exhibits an outlier behaviour. Molecular dynamics simulation results are used to explain the volumetric behaviour along the homologous series from a molecular perspective. The predictive power of group contribution methods for density and viscosity is also tested.

Nucleic acid bases in 1-alkyl-3-methylimidazolium acetate ionic liquids: A thermophysical and ionic conductivity analysis

“…The density increase of the binary samples with nucleobase concentration is shown in Figure 4. This fact can probably be attributed to the strong interactions between the solute and the ionic liquid [41], which agrees with the strong hydrogen bonding between the nucleobases and both the IL anion and cation, determined by NMR spectroscopy in a previous study concerning the dissolution mechanism of nucleobases in 1,3-dialkylimidazolium acetate ILs [8]. We have also observed similar phenomena of increasing density with the solute concentration when mixtures of ionic liquids and simple inorganic salts were studied [42].…”

“…It has already been shown that, despite the highly complex liquid structure of ILs, their volumetric properties behave very near to ideality. Thus, the ILs volume can be taken as the sum of the effective volumes of the constituent cations and anions (V m = V ⁄ c + V ⁄ a ), which have been well defined in the literature [38][39][40][41]. Although the typical predictive power of this algorithm is better than 0.5%, the calculated molar volumes of [ As it is well known, dynamic viscosity is more sensitive to impurities than density and the deviations found between our results and the literature values illustrate exactly this fact, as depicted in figure 2(a) and (b).…”

Evaluation of solubility and partition properties of ampicillin-based ionic liquids

“…This fact can probably be attributed to the more exposed charge of imidazolium cation when compared to that of the tetraalkylammonium cation, where the charge is more hidden due to the presence of four hydrocarbon chains as well as the presence of an acidic proton H-2 from imidazolium cation. These structural differences in terms of the charge accessibility have already been observed by molecular dynamics and used to interpret other phenomena (Blesic et al, 2010;Costa et al, 2012;Marcelino et al, 2007).…”

Group Contribution Methods for Estimation of Selected Physico-Chemical Properties of Organic Compounds

“…for density, thermal expansion and viscosity of cholinium-derived ionic liquids (Costa et al, 2011;Costa et al, 2012), viscosity (Adamová et al, 2011, the glass-transition temperature and fragility (Gacino et al, 2011), experimental data of mixture with ionic liquid were compared with group contribution methods (Cehreli & Gmehling, 2010) or thermophysical properties were studied (Gardas et al, 2010).…”