1-Ethyl-3-methylimidazolium Ethylsulfate in Water, Acetonitrile, and Dichloromethane: Molar Conductivities and Association Constants

Bešter‐Rogač, Marija; Hunger, Johannes; Stoppa, Alexander; Buchner, Richard

doi:10.1021/je101130e

Cited by 66 publications

(42 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On further dilution a smooth transition to the behavior of concentrated electrolyte solutions is observed before long-lived contact ion pairs typical for moderately concentrated electrolyte solutions appear at x 0.1 [36,61,60]. As expected, the degree of ion pairing is strongly dependent on solvent polarity but is always comparable to association constants of common salts with organic cations in these solvents [62,63].…”

Section: Rtils In Polar Solventssupporting

confidence: 70%

Dynamics of RTILs: A comparative dielectric and OKE study

Sonnleitner

Turton

Waselikowski

et al. 2014

Journal of Molecular Liquids

Self Cite

View full text Add to dashboard Cite

The dynamics of room-temperature ionic liquids (RTILs) were studied by investigating their dielectric relaxation (DR) and timeresolved optical Kerr-effect (OKE) spectra in the frequency range of ∼10 MHz to ∼20 THz. For the studied RTILs the OKE and DR spectra are dominated by a relaxation in the GHz region and extend to a relatively sharp band at around 10 THz. Whilst the first feature is mainly associated with the structural relaxation of the fluid through ion rotation (α relaxation), the second indicates the short-time limit of intermolecular dynamics. The rather featureless intermediate region is mainly associated with intermolecular vibrations that are strongly coupled to hindered rotations. In contrast to other RTILs, imidazolium salts show an additional sub-α relaxation which dominates the OKE signal and is indicative of the breathing motion of rather long-lived cages.Mixed with polar solvents RTILs were found to retain their ionic liquid-like character up to relatively high levels of dilution, but with the overall dynamics considerably speeded up. Below RTIL mole fractions of ∼0.2-0.4 these systems behave like conventional electrolyte solutions with more or less pronounced ion pairing.

show abstract

Section: Rtils In Polar Solventssupporting

confidence: 70%

Dynamics of RTILs: A comparative dielectric and OKE study

Sonnleitner

Turton

Waselikowski

et al. 2014

Journal of Molecular Liquids

Self Cite

View full text Add to dashboard Cite

show abstract

“… The cation and anion self‐diffusion coefficients were observed to be identical (Figure ). The molar conductivities (Figure ) confirm that the studied concentration range is beyond the concentration region at which an equilibrium exists mainly between freely dissolved ions and ion pairs For solutions of [C 2 mim][NTf 2 ] in CHCl 3 that displayed separate resonances for the ion‐pair species and aggregate species, the H2 chemical shift was higher (more deshielding) for aggregate species than for the ion‐pair species, whereas the reverse was true for H4 and H5 .…”

Section: Discussionsupporting

confidence: 57%

“…The molar conductivities (Figure ) confirm that the studied concentration range is beyond the concentration region at which an equilibrium exists mainly between freely dissolved ions and ion pairs …”

Section: Discussionmentioning

confidence: 99%

Aggregation Behavior of Several Ionic Liquids in Molecular Solvents of Low Polarity—Indication of a Bimodal Distribution

2016

View full text Add to dashboard Cite

The structure and dynamics of ion pairing and aggregation is studied by concentration- and temperature-dependent measurements of (1) H and (19) F self-diffusion coefficients, viscosity, and conductivity for the following five solutions: 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([Cn mim][NTf2], n=2, 4, 6) in dichloromethane (CH2Cl2), and [C6 mim][NTf2] in tetrahydrofuran (THF) and chlorobenzene (C6 H5 Cl). The temperature dependence of these properties at constant IL concentrations follows the Arrhenius law for all five solutions. The IL-concentration dependence of the respective activation energies obtained from the Arrhenius analysis is nonlinear in the case of conductivity, but indicates linear relationships for viscosity and self-diffusion. All five solutions studied display average solute radius maxima as plotted against IL concentration. The maximum average solute radii follow an order of solvents of CHCl3 >C6 H5 Cl>CH2 Cl2 ≈THF, which corresponds to the order of increasing solvent dielectric constant. The observed trends in the physical properties of these solutions indicate the development of a bimodal distribution of solute size with increasing IL concentration. Specifically, the presence of aggregates is supported by the analysis of the conductivity data and the observation of the same self-diffusion coefficients for the cation and anion. The concurrent presence of freely dissolved ions is supported by the obtained average solute radii that do not exceed the radii of the corresponding ion pairs.

show abstract

“…The corresponding association constants point to full dissociation in water, weak association in acetonitrile, and strong ion pairing in dichloromethane. [44] Using dichloromethane as the solvent, the ion pair formation constant for ILs with BMI, HMI, OMI, and 1-n-butyl-2,3-dimethylimidazolium (BMMI) cations and PF 6 , BF 4 , NTf 2 (NTf 2 = bis([tri]fluoro[methane]sulfonyl)imide), and picrate anions have been determined from the electric conductivity. [45] The ion pair formation is not affected by the cation's alkyl chain lengths, corroborating that the anion coordination occurs preferentially at the cation's ring moiety.…”

mentioning

confidence: 99%

Imidazolium Salt Ion Pairs in Solution

Stassen

Ludwig

Wulf

et al. 2015

Chemistry A European J

169

151

View full text Add to dashboard Cite

The formation, stabilisation and reactivity of contact ion pairs of non-protic imidazolium ionic liquids (ILs) in solution are conceptualized in light of selected experimental evidence as well theoretical calculations reported mainly in the last ten years. Electric conductivity, NMR, ESI-MS and IR data as well as theoretical calculations support not only the formation of contact ion pairs in solution, but also the presence of larger ionic and neutral aggregates even when dissolved in solvents with relatively high dielectric constants, such as acetonitrile and DMSO. The presence of larger imidazolium supramolecular aggregates is favoured at higher salt concentrations in solvents of low dielectric constant for ILs that contain shorter N-alkyl side chains associated with anions of low coordination ability. The stability and reactivity of neutral contact species are also dependent on the nature of the anion, imidazolium substituents, and are more abundant in ILs containing strong coordinating anions, in particular those that can form charge transfer complexes with the imidazolium cation. Finally, some ILs display reactivities as contact ion pairs rather than solvent-separated ions.

show abstract

1-Ethyl-3-methylimidazolium Ethylsulfate in Water, Acetonitrile, and Dichloromethane: Molar Conductivities and Association Constants

Cited by 66 publications

References 34 publications

Dynamics of RTILs: A comparative dielectric and OKE study

Dynamics of RTILs: A comparative dielectric and OKE study

Aggregation Behavior of Several Ionic Liquids in Molecular Solvents of Low Polarity—Indication of a Bimodal Distribution

Imidazolium Salt Ion Pairs in Solution

Contact Info

Product

Resources

About