Ratio Of Activity Coefficients Research Articles

Investigation of Sulfation of CaO and CaCO3 in Eutectic CaF2–CaCl2

To achieve deep cuts in greenhouse gas emissions from stationary point sources such as carbon intensive industry and fossil power generation, carbon capture and storage (CCS) will be a necessity. Carbon capture in molten salts (CCMS) is an emerging technology with high potential. In CCMS, the reversible reaction between calcium oxide (CaO) and carbon dioxide (CO2) to form calcium carbonate (CaCO3) is utilized, with the active substances being dissolved or partly dissolved in molten salts. CCMS has previously demonstrated promising properties for carbon capture with simulated flue gases on the laboratory scale. The next step in the technology development is to test the performance under more realistic gas compositions. In the present work, the focus is on sulfur dioxide (SO2) and oxygen (O2), a combination often coexisting with CO2 in flue gases from power production or industry. Experiments have been performed to investigate indirect sulfation of CaO and direct sulfation of CaCO3 in a eutectic mixture of calcium fluoride (CaF2) and calcium chloride (CaCl2) because it is not known whether these are thermodynamically favored in the molten state. Simulated flue gases containing 0.5 vol % SO2 and 3 vol % O2 have been used. In addition, combined capture experiments with 14 vol % CO2 and levels of SO2 up to 0.5 vol % have been performed. The composition of the outlet gas from the reactor was analyzed by Fourier transform infrared spectroscopy. The results indicate that both direct and indirect sulfation occur and that carbon capture is only slightly, but not significantly, inhibited in accordance with the level of SO2 in the flue gas. Furthermore, it was shown that CO2 capture in molten salts is possible at temperatures above the decomposition temperature for CaCO3 in solid-state calcium looping. This is attributed to higher activities when the active substances are dissolved in molten salts. Based on experimental data and thermodynamic modeling, it was estimated that the ratio of activity coefficients for CaO and CaCO3 is between 5 and 6 when dissolved in eutectic CaF2–CaCl2.

Experimental Determination of the MnO Activity Coefficient in High-Manganese Slags Using the Chemical Equilibrium Method

The thermodynamics of manganese oxide in high-MnO-containing slags was investigated using the chemical equilibrium method in the temperature range of 1623 to 1723 K. MnO-SiO2-Al2O3 slags were brought into equilibrium with molten silver (Ag) under controlled CO/CO2 gas atmosphere. The equilibrium Mn concentration in the silver was measured by ICP-AES (inductively coupled plasma atomic emission spectroscopy) analysis after the experiment. Slag samples were analyzed by EPMA (electron probe microanalyzer) analysis. The obtained activity aMnO and activity coefficient γMnO were derived as a function of the slag composition and temperature. The activity coefficient of MnO within the investigated slag system increased with an increasing MnO/SiO2 ratio. The derived temperature dependence of the activity coefficient and partition ratio of Mn between the metal and the slag was strongly influenced by the slag composition. The thermodynamic assessment of the activity and activity coefficient of MnO was carried out by applying the regular solution model (RSM) on the basis of interaction energies of the cations and with FactSageTM 7.3. The theoretical calculations were compared with the experimentally derived values.

Effect of solution nonideality on cholesterol supersaturation for liquid antisolvent crystallization

The present work aims to analyze the effect of solution non-ideality on the magnitude of supersaturation of cholesterol (3) for crystallization from its solution in organic solvent (2) using water (1) as antisolvent. Real supersaturation (S) has been computed as the ratio of activities (a 3/a 3*) at the supersaturated (x 3) and saturated (x 3*) mole fractions respectively, by multiplying the ideal solution supersaturation (Sx = x 3/x 3*) with the activity coefficient ratio [γ3/γ3*]. The values of [γ3/γ3*] are estimated using the Pharma Modified UNIFAC model. The x 3* data have been measured experimentally in aqueous organic-solvent mixtures at different values of x 1 in ethanol at three temperatures (T) in the range of 290.5 to 299.5 K, and in acetone and acetonitrile at 299.5 K. These data have been correlated in terms of x 1 and T separately for computation of Sx , [γ3/γ3*], and S. The quantitative impact of solution non-ideality on the sensitivity of S to the variations of x 1, x 3, [x 3/x 3*], T and nature of solvent are investigated computationally. It is observed that [γ3/γ3*] is less than 1.0 and is relatively more significant at lower x 1 and higher Sx , though it is almost invariant with T and solvent. The value of Sx at 299.5 K is found higher than S by 15% at Sx = 2 and by 162% at Sx = 10. The results clearly establish that it is necessary to include the solution non-ideality in the estimation of solute supersaturation, as otherwise significant errors may result in computing nucleation and growth rates.

Thermodynamic Properties: Determination of the (NaCl + l-Proline + H2O) Ternary System Based on Potentiometric Measurements at T = (293.2, 303.2 and 313.2) K

In this work, the thermodynamic properties of the ternary (NaCl + l-proline + H2O) system are reported, based on the potentiometric technique. The potentiometric measurements were carried out by using self-made ion selective electrodes (ISE) on the galvanic cell of type Na-ISE | NaCl (mB), l-proline (mA), H2O | Ag/AgCl in various series of the l-proline aqueous solution (mA = 0.2227, 0.4571, 0.7043 and 0.9651) mol·kg−1 and NaCl in pure water over NaCl molalities ranging from (0.01 to 4.00) mol·kg−1 at T = (293.2, 303.2, and 313.2) K and p = 101.3 kPa. Correlation of the experimental data was performed based on the Pitzer model as modified by Esteso et al. (MP). The MP parameters obtained were used to calculate the natural logarithm of the ratio of l-proline activity coefficients in NaCl and water mixtures to l-proline activity coefficients in pure water ( $$\ln ({{\gamma_{{\text{A}}} } \mathord{\left/ {\vphantom {{\gamma_{{\text{A}}} } {\gamma_{{\text{A}}}^{0} }}} \right. \kern-\nulldelimiterspace} {\gamma_{{\text{A}}}^{0} }})$$ ), osmotic coefficients (φ), excess Gibbs energy (GE/RT) and water activity (aw) for different series of l-proline molality. The NaCl transfer Gibbs energy and McMillan–Mayer parameters were also calculated for the system. Good consistency was found between the MP and McMillan–Mayer model parameters.

Comparative optimal design and control of two alternative approaches for separating heterogeneous mixtures isopropyl alcohol-isopropyl acetate-water with four azeotropes

The separation of ternary mixtures with homogeneous or heterogeneous multi-azeotropes has received increasing attention. In this work, a systematic design, optimization and control procedure is proposed for extractive distillation of heterogeneous mixtures with four azeotropes. Herein, the ternary system isopropyl alcohol/isopropyl acetate/water is taken as a case study. The suitable entrainer is first obtained through a proposed approach combining the vapor–liquid equilibrium (VLE) curves and infinite dilution activity coefficient ratios. Conceptual design of two alternative separation sequences involving double-column extractive distillation with a pre-concentrator (DEDP) and triple-column extractive distillation (TED) are then investigated based on thermodynamic insights. With the method of sequential iterative optimization and taking total annual cost (TAC) as the objective function, the two processes are optimized. The optimal results indicate that the DEDP process with dimethyl sulfoxide as entrainer can save 6.43% TAC than that of TED. Finally, a new control structure combining reflux flowrate-to-feed (R/F) and adjustable reboiler duty-to-feed (QR/F) with “HiLoSelect” strategy is proposed to better handle three product purities than that of the basic control structure while feed flowrate and composition disturbances are introduced in the studied DEDP process.

On the estimation of crystallization driving forces

For accurate estimation of crystallization driving forces, activity coefficient ratios need to be estimated.

Prediction of solvent effect on enzyme enantioselectivity

Enantiomeric ratios for the esterification reaction of 2-phenylpropionic acid with 1-octanol catalyzed by immobilized Candida antarctica lipase B in sixteen organic solvents have been measured. Correlation equations that relate the enzyme enantioselectivity with the van der Waals volume (Vw), the van der Waals area (Aw), and the Hildebrand solubility parameters (δ2) of the solvents were obtained, and they were compared with linear solvation energy relationship (LSER) correlation equations, which relates the enzyme enantioselectivity with polarity, acidity, basicity, and Hildebrand solubility parameters of the solvents. Statistical analysis of the experimental data for the esterification reaction investigated here as well as for seven other reactions taken from the literature showed that the pure solvent Vw, Aw and δ2 parameters, sufficiently describe the dependence of enzyme enantioselectivity on the properties of the solvent, yielding better results than the LSER equations that use one more parameter. Furthermore, the enzyme enantioselectivity has been related to the infinite dilution activity coefficients of substrates in the solvent, which are predicted by the COSMO-RS model. It is shown that the predicted by COSMO-RS ratios of infinite dilution activity coefficients of the two enantiomers can be used to correlate satisfactorily the enantiomeric ratios.

Thermodynamics of enzyme-catalyzed esterifications: I. Succinic acid esterification with ethanol.

Succinic acid (SA) was esterified with ethanol using Candida antarctica lipase B immobilized on acrylic resin at 40 and 50°C. Enzyme activity in the reaction medium was assured prior to reaction experiments. Reaction-equilibrium experiments were performed for varying initial molalities of SA and water in the reaction mixtures. This allowed calculating the molality-based apparent equilibrium constant K m as function of concentration and temperature. K m was shown to depend strongly on the molality of water and SA as well as on temperature. It could be concluded that increasing the molality of SA shifted the reaction equilibrium towards the products. Water had a strong effect on the activity of the enzyme and on K m . The concentration dependence of K m values was explained by the activity coefficients of the reacting agents. These were predicted with the thermodynamic models Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT), NRTL, and Universal Quasichemical Functional Group Activity Coefficients (UNIFAC), yielding the ratio of activity coefficients of products and reactants K γ . All model parameters were taken from literature. The models yielded K γ values between 25 and 115. Thus, activity coefficients have a huge impact on the consistent determination of the thermodynamic equilibrium constants K th. Combining K m and PC-SAFT-predicted K γ allowed determining K th and the standard Gibbs energy of reaction as function of temperature. This value was shown to be in very good agreement with results obtained from group contribution methods for Gibbs energy of formation. In contrast, inconsistencies were observed for K th using K γ values from the classical gE-models UNIFAC and NRTL. The importance of activity coefficients opens the door for an optimized reaction setup for enzymatic esterifications.

Crystal Growth of Salicylic Acid in Organic Solvents

The crystal growth rate of salicylic acid has been determined by seeded isothermal desupersaturation experiments in different organic solvents (methanol, acetone, ethyl acetate, and acetonitrile) and at different temperatures (10, 15, 20, and 25 °C). In situ ATR-FTIR spectroscopy and principal component analysis (PCA) were employed for the determination of solution concentration. Activity coefficient ratios are approximately accounted for in the driving force determination. The results show that the dependence of the growth rate on the solvent at equal driving force varies with temperature; e.g., at 25 °C, the growth rate is highest in ethyl acetate and lowest in acetonitrile, while at 15 °C the growth rate is highest in acetonitrile. The growth rate data are further examined within the Burton Cabrera Franck (BCF) and the Birth and Spread (B+S) theories, and the results point to the importance of the surface diffusion step. Interfacial energies determined by fitting the B+S model to the growth rate data a...

Thermodynamic modeling of quaternary (CaCl2 + Ca(NO3)2 + L-alanine + water) system based on potentiometric measurements at T = (298.2, 303.2 and 308.2) K: Experimental measurements and thermodynamic modeling

In this paper, the thermodynamic properties of a quaternary system including CaCl2 and Ca(NO3)2 as mixed electrolytes in the aqueous L-alanine mixture, were reported using the potentiometric method. The potentiometric measurements were performed on the galvanic cells of the type: (a) Ag-AgCl|CaCl2 (mC), H2O|Ca–ISE, (b) NO3-ISE|Ca(NO3)2 (mB), L-alanine (mA = 0.2 mol kg−1), H2O|Ca–ISE, (c) Ag-AgCl|Ca(NO3)2 (mB), L-alanine (mA = 0.2 mol kg−1), H2O|Ca–ISE, and (d) Ag-AgCl|CaCl2 (m1), Ca(NO3)2 (m2), L-alanine (0.2 mol kg−1), H2O|Ca–ISE, over total ionic strengths from 0.0100 to 4.0000 mol kg−1 at T = (298.2, 303.2 and 308.2) K and P = 0.1 MPa. Different series of the salt molal ratios r (r=mCaCl2/mCa(NO3)2= 0.1, 1.0, 2.5, 5.0, 7.5, and 10) and pure Ca(NO3)2 in mixed solvent system containing 0.2 mol kg−1 of L-alanine were used for the potentiometric measurements. The Ca2+ and NO3− ion selective electrodes were prepared in our laboratory using related ionophores. Data analyze was performed based on Pitzer ion interaction model. At the beginning, the mixed ionic interaction parameters (θClNO3, ψCaClNO3) were investigated according to Pitzer graphical method. After that, thermodynamic properties such as the mean activity coefficients, the osmotic coefficients, the solvent activity, the excess Gibbs free energy, the excess enthalpy and the excess entropy for electrolyte solutions were calculated. Moreover, the ratio of L-alanine activity coefficients in presence of electrolyte (γA) to values of this property in absence of electrolyte (γA0) was obtained by Scatchard equation.

Shape and curvature of surface tension isotherms for liquid mixtures

The different shapes of surface tension isotherms consistent with Butler’s ideal model for the planar surface phase of binary liquid mixtures are comprehensively worked out for the first time. Using the ratio of pure constituent molar surface areas and a parameter named surface factor, which depends only on pure-constituent properties, the Butler equation is expressed and solved as a function of these two independent parameters. The geometrical features for the plots of surface tension against the mole fraction of component with lower surface tension are established for every possible combination of those two parameters. Three main shape types are found, namely: concave up (positive curvature); concave down passing through an inflection point followed by concave up; and concave down (negative curvature). The range of parameter values leading to each shape type is obtained and shown graphically. It is demonstrated that Butler’s ideal model excludes the eventuality of a system presenting a shape with initial positive curvature, then an inflection point and continuing with negative curvature. All the above shapes will appear as a mirror image in the representation of surface pressure against mole fraction. Six organic–organic systems, including two ionic liquid solutions, taken from the literature are examined. It is shown that actual Gibbs adsorption isotherm shapes arise from the sum of ideal surface tension deviations with excess surface tensions, the latter being related to the equilibrium surface/bulk ratio of activity coefficients. It is also shown that this ratio is larger for the component with the greatest molar surface area. From the comparison of surface and bulk activity coefficients at the same chemical composition interesting insights into the surface phase are drawn.

Improving Estimates of the Crystallization Driving Force: Investigation into the Dependence on Temperature and Composition of Activity Coefficients in Solution

In this work the influence of temperature and composition on the activity coefficient in solution has been investigated, based on isothermal and isobaric vapor–liquid equilibrium data for 30 binary systems classified into four groups: water–organic, polar–polar, polar–nonpolar, and nonpolar–nonpolar systems. It is shown that under most conditions the temperature dependence of the activity coefficient is clearly weaker than the composition dependence. The analysis is extended to include solid–liquid solubility data of 15 binary systems of relatively large and complex organic molecules in organic solvents. Based on this, a novel approach to estimate the thermodynamic driving force of crystallization from solution is proposed. Rather than assuming that the activity coefficient ratio equals unity, it is shown that in most cases a more accurate assumption is to neglect only the temperature dependence of the activity coefficient. This allows the activity coefficient ratio to be estimated from solid–liquid equil...

Modeling of activity coefficients of amino acid and electrolyte in aqueous solutions

The amino acid exists in the zwitterion form with positive (amino group, −NH3+) and negative (carboxyl group, COO−) charge in water, and it is able to form the ion-pair complexes physically bonded with ions. The ion-pair complex between amino acid and ions has a strong effect on the variation of activity coefficient of amino acid in aqueous electrolyte solution. In this work, the PC-SAFT EOS combined with primitive mean spherical approximation (PM-MSA) model is applied to the 32 amino acid-electrolyte aqueous systems (a total of 1305 data points) for modeling the activity coefficients of amino acids and electrolyte in aqueous solutions. The ion-pair complex is considered as a cross-association between amino acid and ions, and this method accurately represents the activity coefficient of an amino acid and electrolyte over a wide range of concentrations. Based on the calculation of activity coefficient ratio of amino acid, the solubility of an amino acid in electrolyte-water system and density of solution are predicted, and the predicted results show qualitative agreement with experimental results. Therefore, the model proposed in this work is expected to be useful for describing activity coefficients of an electrolyte and amino acid in amino acid-electrolyte-water system.

Measurement and Modeling of Mean Activity Coefficients of NaCl in an Aqueous Mixed Electrolyte Solution Containing Glycine

An electrochemical cell with two ion-selective electrodes (Na\(^{+}\) glass) and (Cl\(^{-}\) solid state) was used to measure the mean ionic activity coefficient of NaCl in an aqueous mixture containing NaCl, glycine, and NaNO\(_{3}\) at 308.15 K. The experiments were conducted at fixed molality of NaNO\(_{3}\) (0.1 m) and various molalities of glycine (0–1 m) and NaCl (up to 0.8 m). The experimental data were modeled using a modified version of the Pitzer equation. Finally the activity coefficient ratio of glycine was determined based on the Maxwell equation.

Thermodynamics of the alanine aminotransferase reaction

The thermodynamic equilibrium of the aminotransferase reaction from l-alanine and 2-oxoglutarate to l-glutamate and pyruvate in aqueous solution was investigated in a temperature range between 25 and 37 °C and pH between at 5 and 9.Prior to considering the reaction equilibria, measurements were carried out to ensure the enzyme activity in the aqueous reaction media. After that, equilibrium concentrations of reacting agents were measured by HPLC-analysis. At constant temperature and pH, reaction equilibrium was shown to depend on the absolute molalities (0.005–0.130 mol kg−1) as well as on the ratio of initial molalities of the reactants. It could be concluded that reaction equilibrium was shifted towards the product site upon increasing reactant molalities, increasing temperature, and increasing pH. Further, yields of pyruvate were increased upon excess initial molality of l-alanine compared to 2-oxoglutarate.The thermodynamic equilibrium constant Ka∗ was determined by extrapolating the ratio of product equilibrium molalites and reactant equilibrium molalites to infinite dilution of all reacting agents. The activity-coefficient ratio of products and reactants in the reaction media was predicted with ePC-SAFT. Combining Ka∗ and the activity-coefficient ratio allowed quantitatively predicting the influence of temperature, pH, and reacting-agent molalities on the reaction equilibrium.

Reduction of chromium oxides in stainless steel dust

The recovery of metal oxides from stainless steel dust using C (graphite), SiFe, and Al as reductants was investigated under various conditions. The apparent distribution ratio of Cr (L′Crm/s) in the recovered metal and residual slag phases was defined as the major performance metric. The results show that the recovery ratio of metals increases as the ratio of CaO:SiO2 by mass in the residual slag increases to 1.17. The residual content of metals in the slag decreases as the Al2O3 content of the slag is increased from approximately 8wt% to 10wt%. The recovery ratio of Cr increases with increasing L′Crm/s, and a linear relationship between L′Crm/s and the activity coefficient ratio of CrO in the slag and the recovered metal phase is observed. The combination of C and SiFe or Al as the reducing agents reveals that Si is the more effective coreductant.

Henry's law constants of polyols

Abstract. Henry's law constants (HLC) are derived for several polyols bearing between 2 and 6 hydroxyl groups, based on literature data for water activity, vapour pressure and/or solubility. While deriving HLC and depending on the case, also infinite dilution activity coefficients (IDACs), solid state vapour pressures or activity coefficient ratios are obtained as intermediate results. An error analysis on the intermediate quantities and the obtained HLC is included. For most compounds, these are the first values reported, while others compare favourably with literature data in most cases. Using these values and those from a previous work (Compernolle and Müller, 2014), an assessment is made on the partitioning of polyols, diacids and hydroxy acids to droplet and aqueous aerosol.

The reaction enthalpy of hydrogen dissociation calculated with the Small System Method from simulation of molecular fluctuations.

We show how we can find the enthalpy of a chemical reaction under non-ideal conditions using the Small System Method to sample molecular dynamics simulation data for fluctuating variables. This method, created with Hill's thermodynamic analysis, is used to find properties in the thermodynamic limit, such as thermodynamic correction factors, partial enthalpies, volumes, heat capacities and compressibility. The values in the thermodynamic limit at (T,V, μj) are then easily transformed into other ensembles, (T,V,Nj) and (T,P,Nj), where the last ensemble gives the partial molar properties which are of interest to chemists. The dissociation of hydrogen from molecules to atoms was used as a convenient model system. Molecular dynamics simulations were performed with three densities; ρ = 0.0052 g cm(-3) (gas), ρ = 0.0191 g cm(-3) (compressed gas) and ρ = 0.0695 g cm(-3) (liquid), and temperatures in the range; T = 3640-20,800 K. The enthalpy of reaction was observed to follow a quadratic trend as a function of temperature for all densities. The enthalpy of reaction was observed to only have a small pressure dependence. With a reference point close to an ideal state (T = 3640 K and ρ = 0.0052 g cm(-3)), we were able to calculate the thermodynamic equilibrium constant, and thus the deviation from ideal conditions for the lowest density. We found the thermodynamic equilibrium constant to increase with increasing temperature, and to have a negligible pressure dependence. Taking the enthalpy variation into account in the calculation of the thermodynamic equilibrium constant, we found the ratio of activity coefficients to be in the order of 0.7-1.0 for the lowest density, indicating repulsive forces between H and H2. This study shows that the compressed gas- and liquid density values at higher temperatures are far from those calculated under ideal conditions. It is important to have a method that can give access to partial molar properties, independent of the ideality of the reacting mixture. Our results show how this can be achieved with the use of the Small System Method.

Speciation of the H2SO4–Fe2(SO4)3–FeSO4–H2O system and development of an expression to predict the redox potential of the Fe3 +/Fe2 + couple up to 150 °C

A thermodynamic model is developed and shown to reliably simulate the speciation of the quaternary H2SO4–Fe2(SO4)3–FeSO4–H2O system through a wide range of solution compositions and temperatures (25°C–150°C). The main species involved (including H+, Fe2+, Fe3+, SO42−, HSO4−, FeHSO4+, FeSO4°, FeHSO42+, Fe(SO4)2−, FeSO4+, Fe2O3 and H2O) were investigated, and their thermodynamic data were collected and critically assessed to evaluate their activity coefficients and equilibrium constants. Results show that the species distribution depends highly on the initial total amount of iron, acidity, nominal Fe3+/Fe2+ ratio and temperature. Modeling results also reveal that most of the Fe(III) is distributed as complexes or precipitates and the free Fe3+ accounts for only a minor percentage, whereas a large amount of Fe(II) exists in the form of free Fe2+, with the rest dissolved as complexes. Moreover, based on the model results, the temperature dependence of the real Fe3+/Fe2+ ratios and their activity coefficient ratios was subsequently obtained and employed to systematically study the redox potential of the Fe3+/Fe2+ couple. The redox potentials predicted by the model increase with the nominal Fe3+/Fe2+ ratio and temperature when the nominal Fe3+/Fe2+ ratios are 10:1, 100:1 and 1000:1, with its values in the range of 736–956mV (all potentials in the present study are quoted with respect to the Standard Hydrogen Electrode at 25°C) from 25°C to 150°C in the studied acidic iron sulfate solutions. At a nominal Fe3+/Fe2+ ratio of 1:1, the predicted potentials are relatively stable with respect to temperature, typically between 671mV and 679mV, because the real Fe3+/Fe2+ ratio in solution is much lower for such a condition. The speciation model explains the change of redox potential with temperature for all nominal Fe3+/Fe2+ ratios. An expression is also developed to calculate the redox potential and is supported by experimental results from the literature. It appears that the redox potential can be easily and accurately determined only based on the variables of temperature and nominal Fe3+/Fe2+ ratio, independent of the nominal concentrations of H2SO4 and Fe3+. Moreover, this expression is probably applicable to more general cases at or around room temperature. The proposed model was validated by reliable prediction of measured redox potential from 25°C to 150°C. Comparison of previously published results of ferric solubility, together with an analysis of the calculated pH and ionic strength, provides additional justification for the model developed herein. These findings contribute to the research on aqueous speciation of acid iron sulfate solutions, the reduction kinetics of the Fe3+/Fe2+ couple, as well as the mechanistic analysis in industrial leaching processes of chalcopyrite and other sulfide minerals.

Effect of Ionic Liquids on Organic Reactions Based on Activity Coefficients at Infinite Dilution

It is important to know how ILs (ionic liquids) influence organic reaction. In this paper, activity coefficients at infinite dilution of more than 80 organic compounds in ILs are collected and analyzed systematically. Through the study on typical organic reactions happened in ILs, such as Diels-Alder, esterification and Friedel-Crafts reaction, the ratio of activity coefficients at infinite dilution of products and reactants is employed to estimate different effects of different structural ILs on the rate and selectivity of reactions.