Phase behaviour and heat capacities of selected 1-ethyl-3-methylimidazolium-based ionic liquids II

Štejfa, Vojtěch; Rohlíček, Ján; Červinka, Ctirad

doi:10.1016/j.jct.2021.106392

Cited by 21 publications

(11 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It holds for most of the investigated ILs that the more the energy released upon formation of the crystal from ion pairs, the more the heat required to melt the crystal. Such a result agrees with our previous finding based on correlations for a smaller set of 11 1ethyl-3-methylimidazolium ionic liquids 109. Correlation of Δ fus H calculated by CL&P-D k with E coh yields a similar picture as the experimental Δ fus H, only with predominant shifts of points to lower Δ fus H values.…”

supporting

confidence: 91%

Does Explicit Polarizability Improve Simulations of Phase Behavior of Ionic Liquids?

Klajmon

Červinka

2021

J. Chem. Theory Comput.

Self Cite

View full text Add to dashboard Cite

Molecular dynamics simulations are performed for a test set of 20 aprotic ionic liquids to investigate whether including an explicit polarizability model in the force field leads to higher accuracy and reliability of the calculated phase behavior properties, especially the enthalpy of fusion. A classical nonpolarizable all-atom optimized potentials for liquid simulations (OPLS) force-field model developed by Canongia Lopes and Padua (CL&P) serves as a reference level of theory. Polarizability is included either in the form of Drude oscillators, resulting in the CL&P-D models, or in the framework of the atomic multipole optimized energetics for biomolecular application (AMOEBA) force field with polarizable atomic sites. Benchmarking of the calculated fusion enthalpy values against the experimental data reveals that overall the nonpolarizable CL&P model and polarizable CL&P-D models perform similarly with average deviations of about 30%. However, fusion enthalpies from the CL&P-D models exhibit a stronger correlation with their experimental counterparts. The least successful predictions are interestingly obtained from AMOEBA (deviation ca. 60%), which may indicate that a reparametrization of this forcefield model is needed to achieve improved predictions of the fusion enthalpy. In general, all FF models tend to underestimate the fusion enthalpies. In addition, quantum chemical calculations are used to compute the electronic cohesive energies of the crystalline phases of the ionic liquids and of the interaction energies within the ion pair. Significant positive correlations are found between the fusion enthalpy and the cohesive energies. The character of the present anions predetermines the magnitude of individual mechanistic components of the interaction energy and related enthalpic and cohesive properties.

show abstract

supporting

confidence: 91%

Does Explicit Polarizability Improve Simulations of Phase Behavior of Ionic Liquids?

Klajmon

Červinka

2021

J. Chem. Theory Comput.

Self Cite

View full text Add to dashboard Cite

show abstract

“…For these compounds, new samples were prepared and vacuum-dried for 14 days at 298 K and 70 Pa. Within the standard procedure, we were typically able to reduce the water content below 500 ppm; , however, Karl-Fischer titration showed that the samples dried at lower temperatures contain up to 2000 ppm of water. The residual water content in these samples is reflected in the treatment and uncertainty of the experimental data.…”

Section: Methodsmentioning

confidence: 99%

“…As a continuation of our systematic efforts, − eight ILs containing 1-butylpyridinium cations, [BPy], together with various anions, were chosen for the present work. Although less stable than imidazolium ILs, these compounds showed a higher performance for the separation of aromatic compounds from alkane mixtures compared to industrially used sulfolane .…”

Section: Introductionmentioning

confidence: 99%

Calorimetric and Crystallographic Phase-Behavior Study of Selected 1-Butylpyridinium Ionic Liquids

Kocian

Štejfa

Rohlíček

et al. 2023

Crystal Growth & Design

Self Cite

View full text Add to dashboard Cite

Despite the growing popularity of ionic liquids (ILs) as attractive solvents with various interesting properties, the lack of low-uncertainty thermodynamic data persists for many of these compounds. Even for commonly available ILs, crucial parameters such as melting temperatures and fusion enthalpies are often unknown or remain burdened with significant uncertainties. Therefore, this study focuses on a thorough characterization of the phase behavior for eight ionic liquids containing the 1butylpyridinium cation by means of differential scanning calorimetry and variabletemperature X-ray powder diffraction. In addition to phase behavior studies, the heat capacities of the ILs were determined using a Tian-Calvet-type calorimeter. For many of the compounds studied, the presented data are the first of their kind. Four of the targeted ILs exhibit polymorphic behavior, but its particular manifestations differ noticeably. The crystal-crystal phase transition in [BPy][NTf 2 ] is irreversible and barely noticeable by both methods used, while the phase transition in [BPy][OTf] is associated with a phase change entropy of a magnitude similar to the melting of the same compound. [BPy][PF 6 ] exhibits a textbook example of a lambda-shaped second-order phase transition between two crystalline phases, being a rare phenomenon that is more often observed with superfluids. Crystal structures of both polymorphs of [BPy][PF 6 ] and [BPy][OTf] are resolved and may act as a solid foundation for future theoretical computations.

show abstract

“… a Standard uncertainties u are as follows: u ( T g ) = 0.3 K, u (Δ g C p ) = 3.3 J·mol –1 K –1 , and u ( p ) = 3 kPa. b ref . c ref . d Glass transition temperature, T g /K, and heat capacity at the glass transition temperature, Δ g C p /J·mol –1 ·K –1 , measured using the DSC technique at atmospheric pressure ( p = 0.1 MPa). …”

Section: Methodsmentioning

confidence: 99%

Thermodynamic Properties of {Diethyl Phosphate-Based Ionic Liquid (1) + Ethanol (2)} Systems, Experimental Data and Correlation

Skonieczny

Królikowska

2022

J. Chem. Eng. Data

View full text Add to dashboard Cite

In this work, three solutions consisting of ionic liquid and ethanol were considered for forward-looking use in absorption refrigeration technology. It is proposed to use the following ionic liquids as absorbents: 1-ethyl-3-methylimidazolium diethyl phosphate (abbreviated as [EMIM][DEP]), 4-ethyl-4-methylmorpholinium diethyl phosphate ([EMMOR][DEP]), and 1-ethyl-1-methyl-pyrrolidinium diethyl phosphate ([EMPYR][DEP]). Since the thermodynamic and physicochemical properties of working fluids determine the efficiency of the refrigerator while looking for alternative operating fluids, it is crucial to perform their extensive characteristics. Therefore, in this work, (vapor + liquid) phase equilibria (VLE), liquid density (ρ), and dynamic viscosity (η) were determined for the ethanolic solution of the three mentioned diethyl phosphate-based ionic liquids. The isothermal VLE was measured by an ebulliometric method within a temperature range from T = (328.15 to 348.15) K with an increment of 10 K and pressures up to 90 kPa. Non-random two-liquid (NRTL) equation with temperature-dependence parameters was used to correlate experimental data. Physicochemical properties including liquid density and dynamic viscosity were determined at temperatures from (293.15 to 338.15) K at ambient pressure over the whole concentration range. These properties were correlated using empirical equations. From experimental density and viscosity data, the excess molar volumes and the deviations from additivity were determined and correlated using the Redlich–Kister-type equation. Two of the tested ILs, [EMMOR][DEP] and [EMPYR][DEP], were synthesized and characterized using NMR analysis. The thermophysical characterizations of pure compounds, including glass transition temperature (T g) and heat capacity at the glass transition temperature (Δg C p), have been determined using a differential scanning calorimetry technique (DSC) at atmospheric pressure. The work presented is a combination of basic studies on the effect of the cation structure of an ionic liquid on the properties of their solutions with ethanol, with the possibility of future application of the tested systems in a viable refrigeration system.

show abstract

Phase behaviour and heat capacities of selected 1-ethyl-3-methylimidazolium-based ionic liquids II

Cited by 21 publications

References 57 publications

Does Explicit Polarizability Improve Simulations of Phase Behavior of Ionic Liquids?

Does Explicit Polarizability Improve Simulations of Phase Behavior of Ionic Liquids?

Calorimetric and Crystallographic Phase-Behavior Study of Selected 1-Butylpyridinium Ionic Liquids

Thermodynamic Properties of {Diethyl Phosphate-Based Ionic Liquid (1) + Ethanol (2)} Systems, Experimental Data and Correlation

Contact Info

Product

Resources

About