Infinite Dilution Activity Coefficient Values Research Articles

1.6-Hexanediol based deep eutectic solvent and their excess data at infinite dilution

For over two decades, deep eutectic solvents have offered pre-eminence characteristics with the purpose of improving the issues of both ionic liquids and traditional solvents. The affordability, ease of preparation, in-flammability, non-or low toxicity, biodegradability, and other environmental advantages of DESs make them more appealing as green solvents. In the present study, 1-ethyl-1-methylpyrrolidinium bromide, a hydrogen bond accepter (HBA), was paired with 1,6-hexanediol (1,6-HDO), a hydrogen bond donor (HBD), to produce a DES with a mole ratio of 1:2. With the use of gas liquid chromatography (GLC), the infinite dilution activity coefficients (IDACs) of 32 different solutes were measured at different temperatures (313.15–343.15) K and atmospheric pressures. The partial molar properties, i.e., enthalpy, entropy, and Gibbs free energy, were calculated from the IDAC values at a reference temperature of T = 313.15 K to give more details for molecular interaction interpretation. Lastly, the selectivity and capacity values of separation problems such as benzene/acetone, benzene/cyclohexane, and cyclohexane/acetone were calculated from the IDAC values. The investigated DES was discovered to have good performance and could be used in industrial processes such as petroleum distillation, separation, extraction, and so on.

Prediction of infinite dilution activity coefficient of alcohol in ionic liquids using group contribution method

Group contribution (GC) method is one of the predictive models used to estimate the thermodynamics properties of a compound. In this work, GC is applied to develop a predictive model to estimate the infinite dilution activity coefficient (IDAC) of ethanol and propanol in ionic liquids (ILs). Developing a GC model is easier compared to other models that require 3 or more parameters. GC method has rarely been used to estimate the chemical potential of alcohol solutes in ILs. Thus, a simple two parameters van't Hoff model using multiple linear regression (MLR) is applied and fitted by generalized reduced gradient (GRG) non-linear algorithm to calculate the IDAC values of alcohol solutes in ILs. The GC model predicted IDAC values that are based on the structure of interacting species is then, compared to the experimental values obtained from literature. The developed model is known to be in best performance if the differences between predicted and experimental IDAC values are at the least. The percentage of difference or deviation between the estimated and experimental IDAC values was determined using the absolute average relative deviation (AARD). 46 ILs with varying anions and cations are used in developing a predictive model at different temperature based on the alcohol solutes. An overall AARD value of 7.49% and 9.91% is obtained from ethanol and propanol solute, respectively, that was formed by the combination of training and validation set. The efficiency of the model with lesser than 10% deviation has been validated by the comparison between predicted and experimental IDAC values based on anion, cation headgroup, and alkyl chain length. Hydrogen bonding basicity of anion and an increase in the alkyl chain of cation headgroup contribute an important role in their interaction with ethanol and propanol as a notable reduction of IDAC values could be observed. The effect of IL's structural characteristics on IDAC is discernible, which aids in designing several ILs that have enhanced interaction with alcohol solutes.

Infinite dilution activity coefficient of solvents in poly-3-hydroxybutyrate from inverse gas chromatography

Over the past few years, there has been an increase in the production of biopolymers, including poly(3-hydroxybutyrate) P(3HB). However, finding compatible solvents for these new materials can be a challenging task. The infinite dilution activity coefficient (IDAC) is a thermodynamic property that indicates the level of interactions between two substances and can be determined from experiments of inverse gas chromatography (IGC). In this work, IGC was used to determine IDAC of 12 solvents in P(3HB). The substances studied were 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), 1,2-dichloroethane, 2,2,2-trifluoroethanol, 2-butanone, 2-heptanone, benzene, chloroform, cyclohexane, dimethyl carbonate, ethyl acetate, isooctane and toluene. HFIP was found to be the most compatible solvent with P(3HB) with IDAC values smaller than 1. Isooctane presented the highest IDAC value, in agreement with the well known incompatibility between hydrocarbons and P(3HB). In addition, P(3HB) crystallinity was determined through IGC technique, enabling the calculation of the IDAC of amorphous phase only, where vapor-liquid equilibrium can be assumed. The degree of crystallinity obtained with HFIP analysis in P(3HB) was 68%, a value close to that previously reported in the literature.

Infinite Dilution Activity Coefficients as Constraints for Force Field Parametrization and Method Development.

Molecular simulations begin with an underlying energy model or force field and from this can predict diverse physical properties. However, force fields were often developed with relatively limited data sets, yet accuracy for diverse properties across a broad chemical space is desirable; therefore, tests of such accuracy are particularly important. Here, to this end, we calculated 237 infinite dilution activity coefficients (IDACs), comparing with experimental values from NIST's ThermoML database. We found that calculated IDAC values correlate strongly with experiment (Pearson R of 0.92 ± 0.01) and allow us to identify specific functional groups that appear to present challenges to the force field employed. One potentially valuable aspect of IDACs, as compared to solvation free energies, which have been frequently employed as force field tests, is that the same molecules serve both as solutes and solvents in different cases, allowing us to ensure that force fields are not overly tuned to one particular environment or solvent.

Measurement and modeling of infinite dilution activity coefficients of organic compounds in an equimolar ionic liquid mixture of [Bmim]Cl and [Bmim][Tf2N

Infinite dilution activity coefficients (IDAC) of solutes (benzene derivatives, primary alcohols, furan derivatives) in pure 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), in pure 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][Tf2N]) and in an equimolar ionic liquid mixture ([Bmim]Cl and [Bmim][Tf2N]) were measured with a chromatographic technique at atmospheric pressure and at (313 to 353) K. The IDAC values for solutes in the ionic liquid mixture were found to lie between their values in the pure ionic liquids meaning that the solute selectivities can be adjusted with ionic liquid composition and that the solute selectivities always lie between those in the pure ionic liquids. IDAC data could be correlated with the ε*-modified Sanchez-Lacombe equation of state with average relative deviations of less than 1.3%. Infinite dilution partition coefficients for solutes in supercritical CO2 – ionic liquid biphasic systems estimated from interaction parameters obtained from atmospheric pressure IDAC values were found to improve the reliability of high-pressure calculations.

Optimization and quantum chemical predictions for the dehydrogenation kinetics of Ammonia Borane–Ionic Liquid mixtures

This work attempts to predict the reaction kinetics of two different hydrogen storage pathways namely Ammonia Borane (AB) and Ionic Liquid (IL) assisted AB. The reaction kinetics has been predicted for six reported ILs at 85 °C with AB using the Multiobjective GA toolbox. In addition, solid state AB thermal decomposition at 85 °C has been also studied. It was found that the Avrami Erofeyev model which is known to be useful for AB + IL mixtures, however fails when applied to predict reaction kinetics for solid state AB decomposition. To overcome this challenge we have used logistic growth model for solid state decomposition. Thus we propose a logistic growth model for solid AB decomposition while an Avrami Erofeyev model for AB–IL mixtures. The logistic growth model was characterized by a single step reaction for the solid state decomposition of AB, while the Avrami Erofeyev model for AB + IL mixtures successfully predicted two single step reactions. Both the models were able to reproduce the experimental trends with an overall deviation of less than 2%.We have also attempted to correlate the Infinite Dilution Activity Coefficient (IDAC) value of AB in IL with the activation energies of the mixture using the quantum chemical based COSMO-RS theory. All the IDAC values being close to unity indicated a high solubility with IL. A general trend of increase in hydrogen release with decreasing IDAC values was observed for the AB–IL mixtures.

Solubility prediction of bio-oil derived chemicals in aqueous media by Localized Molecular Orbital-Energy Decomposition Analysis (LMO-EDA) and COSMO-RS predictions

A series of hydrogen bonding complexes which include Glycolaldehyde⋯water, Furfural⋯water, Acetic acid⋯water and Furanone⋯water were for the first time analyzed by Localized Molecular Orbital-Energy Decomposition Analysis (LMO-EDA) for the prediction of solubility. Stable equilibrium structures of complexes in gas phase were determined by second-order Møller–Plesset perturbation theory (MP2) with 6-311++G(d,p) basis set. Initially conformer analysis was performed on all the solutes and the complexes to choose the minimum energy conformer. It has been found that the most stable structure of Glycolaldehyde and Acetic acid made a cyclic complex with water and was bonded together by two H-bonds which make them unique as compared to Furanone and Furfural. Thereafter with the minimum energy conformer of the solute, the COSMO (COnductor like Screening MOdel) model displaying the distribution of screening charges on a molecular surface was obtained. Subsequently a qualitative analysis based on the sigma profile explained the high distribution coefficients of Glycolaldehyde and Acetic acid. LMO-EDA based Interaction energy and its constituent energy terms (Electrostatic Energy, Exchange Energy, Repulsion Energy, Polarization Energy, and dispersion Energy) were then determined, where the reported and predicted solubility parameters of water in these compounds were found to be: Acetic acid>Glycolaldehyde>Furanone>Furfural. The same trend was also confirmed when comparing the COSMO-RS predicted Infinite Dilution Activity Coefficients (IDAC) of the components in water. An inverse relation was thus obtained between the predicted IDAC values and the LMO-EDA based interaction energies.

Thermodynamic Insights in the Separation of Cellulose/Hemicellulose Components from Lignocellulosic Biomass Using Ionic Liquids

This work reports on the ionic liquid (IL) based separation of cellulose/hemicellulose from lignocellulosic biomass, by means of macroscale predictions using the COnductor like Screening MOdel for Real Solvents (COSMO-RS) model that is based on a statistical mechanical framework. For the benchmarking studies the experimental infinite dilution activity coefficient values for 13 components were predicted in 1-alkyl-3-methylimidazolium bis{(trifluoromethyl)sulphonyl}imide with an average absolute deviation (%AAD) of 15 %. Further, the solid–liquid equilibria of glucose, fructose, galactose, and xylose in [EMIM][EtSO4] and Aliquat®336 were predicted successfully with 15 % root-mean-square deviation. Afterwards, the selectivities were predicted at infinite dilution for cellulose/hemicellulose in 1,156 ILs with a combination of 34 cations and 34 anions. Based on these values, the ammonium-based ILs 1-methyl-4-aminotriazolium hexafluorophosphate [14MATAZ][PF6] and 4-aminotriazolium bis(oxalato(2)borate) [4ATAZ][BOB] were found to be good candidates for cellulose and hemicellulose extraction, respectively. The ILs selected using the COSMO-RS methodology were then studied qualitatively in terms of interaction energies and HOMO–LUMO energy gap. The binding energy for [1-methyl-4-aminotriazolium][PF6] + cellulose and [4-aminotriazolium][BOB] + cellulose systems are higher as compared with IL + cellulose + hemicellulose, indicating greater stability.

Activity coefficients at infinite dilution of organic solutes in the ionic liquid trihexyl(tetradecyl)phosphonium tetrafluoroborate using gas–liquid chromatography at T = (313.15, 333.15, 353.15, and 373.15) K

Activity coefficients at infinite dilution have been measured by gas–liquid chromatography for 27 organic solutes (n-alkanes, 1-alkenes, 1-alkynes, cycloalkanes, aromatics, alcohols, and ketones) in the ionic liquid trihexyl(tetradecyl)phosphonium tetrafluoroborate [3C 6C 14P][BF 4]. The measurements were carried out at four different temperatures viz. T = (313.15, 333.15, 353.15, and 373.15) K. From the experimental data, partial molar excess enthalpy values at infinite dilution were calculated for the experimental temperature range. The selectivity values for the separation of n-hexane/benzene, cyclohexane/benzene, and methanol/benzene mixtures were determined from the experimental infinite dilution activity coefficient values. These values were compared to those available in the literature for other ionic liquids and commercial solvents, so as to assess the feasibility of employing [3C 6C 14P][BF 4] in solvent-enhanced industrial separations.

Gas-liquid chromatography measurements of activity coefficients at infinite dilution of hydrocarbons and alkanols in 1-alkyl-3-methylimidazolium bis(oxalato)borate

The activity coefficients at infinite dilution, γ i ∞ for various solutes: alkanes, cycloalkanes, 1-alkenes, 1-alkynes, benzene, alkylbenzenes, and alcohols in the ionic liquids 1-butyl-3-methylimidazolium bis(oxalato)borate [BMIM][BOB] and 1-hexyl-3-methyl-imidazolium bis(oxalato)borate [HMIM][BOB] have been determined by gas-liquid chromatography at the temperatures ranging from 308 to 348 K. The partial molar excess enthalpies at infinite dilution H i E , ∞ of the solutes in the ionic liquids were also derived from the temperature dependence of the γ i ∞ values. The selectivities for the hexane/benzene, cyclohexane/benzene and hexane/hexene separation problems were calculated from experimental infinite dilution activity coefficient values and compared to the other ionic liquids, taken from the recent literatures.

COSMO-RS-Based Screening of Ionic Liquids as Green Solvents in Denitrification Studies

Five- and six-membered heteroaromatic nitrogen compounds play an inhibiting role in the hydrodesulfurization of diesel oil. In this work, the ionic liquids (ILs) are used as green solvents to remove such compounds by liquid−liquid extraction (LLE). Approximately 168 ILs comprising cations which include 1-ethyl-3-methylimidaozlium [EMIM], 1-ethylpyridinium [EPY], 1-ethyl-1-methyl pyrrolidinium [EPYRO], 1-ethyl-1-methylpiperidinium [EMPIP], 4-ethyl-4-methyl morpholinium [EMMOR], and 1,2,4-trimethylpyrazolium[TMPYZO] combined with 26 anions were investigated in this work. The infinite dilution activity coefficient (IDAC) was predicted through the conductor-like screening model for real solvents (COSMO-RS) model in order to screen the potential solvents. Initially the model was benchmarked via IDAC and LLE predictions. LLE was predicted for four reported ternary systems in which a nitrogen heterocycle was one of the compounds. The average root-mean-square deviation (rmsd) obtained was 10%. The IDAC values wer...

Activity coefficients at infinite dilution of organic solutes in N-alkylpyridinium bis(trifluoromethylsulfonyl)imide ([C nPY][NTf 2], n = 2, 4, 5) using gas–liquid chromatography

The activity coefficients at infinite dilution, γ i ∞ for both polar and non-polar solutes in the ionic liquids N-alkylpyridinium bis(trifluoromethylsulfonyl)imide ([C n PY][NTf 2], n = 2, 4, 5) have been determined by gas–liquid chromatography using the ionic liquid as the stationary phase. The measurements were carried out at the temperatures from (303 to 353) K. The partial molar excess enthalpies at infinite dilution H i E, ∞ of the solutes in the ionic liquids were also derived from the temperature dependence of the γ i ∞ values. The values of the selectivity for the hexane/benzene and cyclohexane/benzene separation problems were calculated from experimental infinite dilution activity coefficient values and compared to the other ionic liquids, taken from the recent literatures.

Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate [EMIM][TCB] using gas–liquid chromatography

The activity coefficients at infinite dilution, γ i ∞ , for both polar and non-polar solutes in the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate [EMIM][TCB] have been determined by gas–liquid chromatography at the temperatures from (303 to 343) K. The partial molar excess enthalpies at infinite dilution H i E, ∞ of the solutes in the ionic liquid were also calculated from the temperature dependence of the γ i ∞ values. The selectivity for the hexane/benzene and cyclohexane/benzene separation problems was calculated from experimental infinite dilution activity coefficient values and compared to the other ionic liquids, taken from the recent literature.

Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate using gas–liquid chromatography at T = (313.15, 323.15, and 333.15) K

Activity coefficients at infinite dilution were determined for 24 solutes (n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes, and alcohols) in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate by gas-liquid chromatography at three different temperatures T = (313.15, 323.15, 333.15) K. The partial molar excess enthalpy values at infinite dilution were calculated from the experimental results over the same temperature range. Selectivities and capacities at infinite dilution for the hexane/benzene and methanol/benzene separation problems were calculated from experimental infinite dilution activity coefficient values. The activity coefficients, enthalpies, selectivities, and capacities are discussed and compared to literature values for other ionic liquids, as well as industrial molecular solvents.

Correlation and Prediction of Phase Behavior of Organic Compounds in Ionic Liquids Using the Nonrandom Two-Liquid Segment Activity Coefficient Model

Room-temperature ionic liquids have shown great potential as media for reactions and separations. Information on how organic compounds interact with these ionic liquids is crucial in assessing their usefulness. Here, the nonrandom two-liquid segment activity coefficient (NRTL-SAC) model is used first to correlate values of infinite-dilution activity coefficients for organic compounds in ionic liquids and then to predict the phase behavior of various mixtures involving these ionic liquids. NRTL-SAC provides a robust, qualitative predictive model based on four molecular descriptors that are designed to capture molecular surface interaction characteristics: hydrophobicity, hydrophilicity, polarity, and solvation strength.

Predicting Infinite-Dilution Activity Coefficients of Organic Solutes in Ionic Liquids

Room-temperature ionic liquids have shown great potential as media for reactions and separations. Information on how solutes interact with these solvents is crucial in assessing their usefulness. Here, the quantitative structure−property relationship (QSPR) method is used to correlate values of infinite-dilution activity coefficients for 38 solutes in three ionic liquids. Constant-temperature and temperature-dependent correlations are created with correlation coefficients ranging from R2 = 0.90 to R2 = 0.99. In addition, correlation parameters are analyzed to understand the interactions that affect infinite-dilution activity coefficients.

Effect of Some Inorganic Salts on the Ternary Liquid−Liquid Equilibria of the Water + 4-Methyl-2-pentanone + Propanoic or Butanoic Acid at 35 °C

The effect of sodium chloride, sodium nitrate, sodium sulfate, zinc sulfate, and ammonium sulfate on the liquid−liquid equilibria (LLE) of water + 4-methyl-2-pentanone + propanoic or butanoic acid at 35 °C has been studied. The ternary LLE data of the systems have been predicted using the NRTL equation, the parameters of which were obtained from the infinite dilution activity coefficient values. The distribution data of the salt containing ternary liquid systems have been correlated through the use of the modified Campbell equation, and the constants obtained have been used to determine the extract phase solute concentrations and also to calculate the salt effect parameter. Results based on the modified Campbell equation show the following order of effectiveness of salts for systems containing propanoic acid: Na2SO4 > ZnSO4 > NaCl > (NH4)2SO4 > NaNO3. And for systems with butanoic acid: (NH4)2SO4 > Na2SO4 > NaCl > ZnSO4 > NaNO3.

Study of initial state and transition state solvation in the Menschutkin reaction of triethylamine with ethyl iodide in alcohols from infinite dilution activity coefficients

AbstractThe Gibbs energies of activation of the Menschutkin reactions of trethylamine with ethyl iodide in 10 monoalcohols and nine dialcohols, were dissected into contributions from the initial state and transition state. To perform this study, the infinite dilution activity coefficient values of the solutes in the solvents, γ∞, were determined by the UNIFAC group‐contribution method, using the modified Flory–Huggins equation in the combinatorial term. For triethylamine, the γ∞ values were calculated using group‐interaction parameters from the VLE Parameter Table, due to the nonavailability of specific γ∞ UNIFAC interaction parameters for the relevant groups. For ethyl iodide, the γ∞ values were calculated using the group‐interaction parameters from the specific γ∞ UNIFAC Parameter Table, except for the solvents diethylene glycol and triethlene glycol, where VLE parameters were used for the same reasons as explained above for the triethylamine. The results were compared with those obtained for the unimolecular decomposition of tert‐butyl halides. For the Menschutkin reaction, we conclude that solvent disruption and reorganization to a state appropriate to solvating the molecular species is a dominant interaction mechanisim.

Study of initial‐ and transition‐state solvation in the solvolysis of tert‐butyl halides in alcohols from infinite dilution activity coefficients

AbstractThe Gibbs energies of activation of the solvolytic reactions of tert‐butyl halides (chloride, bromide and iodide) in eight mono‐alcohols and eight di‐alcohols were dissected into contributions from the initial state and transition state. The unified approach proposed by Abraham was applied and the various factors making up the overall solvent effect in both states were identified and compared. To perform this study, the Gibbs energies of transfer of the initial state were calculated using the infinite dilution activity coefficient values of the solutes in the solvents, γ∞. These values were determined from the UNIFAC group‐contribution method, with the modified Flory–Huggins equation in the combinatorial term and with group interaction parameters from the Parameter Table exclusively based on experimental γ∞ data reported in the literature. It is concluded that solvent polarizability and polarity–HBD acidity and cavity effects during the activated process are mainly due to transition‐state contributions.

Infinite Dilution Activity Coefficient Values from Total Pressure VLE Data. Effect of Equation of State Used

Infinite Dilution Activity Coefficient Values from Total Pressure VLE Data. Effect of Equation of State Used