Dilution Partial Molar Excess Enthalpies Research Articles

Infinite Dilution Activity Coefficients and Gas–Liquid Partition Coefficients of Organic Compounds in Ionic Liquid 1-Butyl-2,3-dimethylimidazolium Thiocyanate: Measurements and LFER Calculations

Infinite dilution activity coefficients (γi∞) of 31 organic solutes (alkanes, cycloalkanes, olefins, aromatics, chlorinated alkanes, alcohols, and other polar organic solutes) in the ionic liquid (IL) 1-butyl-2,3-dimethylimidazole thiocyanate ([BMMIM][SCN]) were determined by gas–liquid chromatographic (GLC) method in the temperature range of 313.15–353.15 K. The infinite dilution partial molar excess enthalpies (H̅iE, ∞), entropies (TrefS̅iE, ∞), and Gibbs free energies (G̅iE, ∞) of the organic solutes at the reference temperature T = 298.15 K and the solubility parameters (δ3) of [BMMIM][SCN] were derived from γi∞. The gas–liquid partition coefficients (KL) of solutes at different temperatures were calculated by referring to the densities of [BMMIM][SCN]. The linear free energy relationship solvation model was used to fit the KL values, and the KL prediction model was obtained. The selectivity (Sij∞) and capacity (kj∞) of n-hexane (i)/benzene (j) and cyclohexane (i)/benzene (j) at infinite dilution at 323.15 K were calculated. The results were compared with the values of ILs with the thiocyanate anion in the literature.

Comments on “Solubility measurement and correlation of 2-phenyl-1H-indole in fourteen mono organic solvents from 289.05 K to 338.55 K”

Abstract A polemic is given regarding the thermodynamic properties reported in the published paper. The authors' calculated infinite dilution activity coefficients and infinite dilution partial molar excess enthalpies of 2-phenyl-1H-indole are found to be inconsistent with the Wilson model curve-fit parameters reported in the paper.

Thermodynamic properties of five biofuel-relevant compounds at infinite dilution in water

In this work, thermodynamic behavior of five biomass-derived compounds, namely furfural, 2-methylfuran, 2,5-dimethylfuran, methyl vinyl ketone, and allyl alcohol, in highly dilute aqueous solutions has been experimentally investigated. Using the inert gas stripping technique, their air-water partition coefficients (Kaw) and limiting activity coefficients γ1∞ were measured at several temperatures in the range from (273 to 333) K. Except for the furans, infinite dilution partial molar excess enthalpies and volumes were further determined as functions of temperature from (288 to 318) K by tandem flow mixing calorimetry and vibrating-tube densimetry, which in turn allowed reliable derivation of respective heat capacities and expansivities. In addition, densities of all five pure liquids and viscosities of furfural and allyl alcohol were also measured in the range from (288 to 318) K. For each compound, the vapor-liquid equilibrium and (when measured) calorimetric data of this work together with some relevant data reported previously in the literature were simultaneously correlated by a three-parameter model equation providing adequate simultaneous description of all information involved. As a result, recommended thermodynamically consistent temperature dependences of Kaw and γ1∞ of superior accuracy were thus established in the range from the melting point to the normal boiling point of water. The variation of Kaw and γ1∞ with temperature and solute molecular structure along with related energetic functions of dissolution and hydration of the examined compounds were overviewed and briefly discussed.

Temperature dependence of limiting activity coefficients, Henry's law constants, and related infinite dilution properties of C4–C6 isomeric n-alkyl ethanoates/ethyl n-alkanoates in water. Measurement, critical compilation, correlation, and recommended data

Infinite dilution activity coefficients (γ1∞) of C4–C6 isomeric n-alkyl ethanoates/ethyl alkanoates, namely ethyl ethanoate, propyl ethanoate, ethyl propanoate, butyl ethanoate, ethyl butanoate in water were measured at several temperatures in the range from (273 to 361)K. Most measurements were carried out by the inert gas stripping method, although other three headspace gas chromatography techniques were also employed. A comprehensive critical review is further presented of literature data on γ1∞, infinite dilution partial molar excess enthalpies (H¯1E,∞) and heat capacities (C¯p,1E,∞) of these aqueous solutes. For each ester, the data measured in this work together with those reported previously in the literature were correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, a recommended temperature dependence of γ1∞ of superior accuracy was established. The consistency of recommended γ1∞(T) with literature data on mutual solubilities of esters and water was also demonstrated. Analogous recommendations were derived also for the temperature dependence of Henry's law constants (KH). The variation with temperature and ester molecular structure of γ1∞, KH, and related energetic functions of ester dissolution and hydration was overviewed and briefly discussed. Furthermore, the performance of five predictive approaches to estimate γ1∞(T) of the aqueous esters was tested.

Determination of Infinite Dilution Partial Molar Excess Enthalpies and Volumes for Some Ionic Liquid Precursors in Water and Methanol Using Tandem Flow Mixing Calorimetry and Vibrating-Tube Densimetry

A flow mixing microcalorimetric system we developed recently was appended in this work with a vibrating tube densimeter into a tandem flow arrangement. This new combined apparatus (calo/densimeter) allows simultaneous automatic measurement of mixing enthalpies and densities of highly dilute solutions as a function of composition and, in turn, reliable determination of the solute's infinite dilution partial molar excess enthalpies H̅1E,∞ and volumes V̅1E,∞. The performance of the calo/densimeter was verified using 1-propanol in water, and then the apparatus was employed to determine H̅1E,∞ and V̅1E,∞ of several ionic liquid precursors (N-methylimidazole, N-methylpiperidine, N-methylmorpholine, 2-picoline, 3-picoline, and 2,6-lutidine) in water and methanol at 298.15 K. The changes of enthalpy associated with solvation and the transfer of the solutes from water to methanol were evaluated. The thermodynamic behavior observed for individual solutes was compared and briefly discussed in terms of molecular interactions.

Activity coefficients and partial molar excess enthalpies at infinite dilution for four esters in water

Infinite dilution activity coefficients ( γ 1 ∞ ) of four esters, namely dimethyl carbonate, diethyl carbonate, vinyl acetate, and methyl methacrylate in water were measured at several temperatures in the range from 273 K to 333 K. The inert gas stripping technique, and for methyl methacrylate also the headspace analysis with solid-phase microextraction sampling, was employed for the purpose. Infinite dilution partial molar excess enthalpies ( H ¯ 1 E , ∞ ) of these aqueous solutes were further measured at several temperatures in the range from 288 K to 318 K using isothermal flow mixing microcalorimetry which allowed reliable derivation of respective heat capacities ( C ¯ p , 1 E , ∞ ). For each ester, the data measured in this work together with those reported previously in the literature were correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, a recommended thermodynamically consistent temperature dependence of γ 1 ∞ of superior accuracy was established. Analogous recommendations were derived also for the temperature dependence of the Henry's law constants ( K H). In addition, literature data on mutual solubilities of esters and water were employed to calculate the γ 1 ∞ values which in turn were compared with the recommended γ 1 ∞ ( T ) dependences.

Temperature Dependence of Limiting Activity Coefficients, Henry’s Law Constants, and Related Infinite Dilution Properties of Branched Pentanols in Water. Measurement, Critical Compilation, Correlation, and Recommended Data

Limiting activity coefficients (γ1∞) of six branched pentanols (2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, and 3-methyl-2-butanol) in water were measured at several temperatures covering the range from the melting to the normal boiling point of water. Five experimental techniques, namely, inert gas stripping, headspace analysis in two variants, the classical and the relative, Rayleigh distillation, and the method of circulation still, were employed for the purpose. A comprehensive review is further presented of experimental data on the limiting activity coefficients, γ1∞, infinite dilution partial molar excess enthalpies (H1E,∞), and heat capacities (Cp,1E,∞) of these aqueous solutes. Since H1E,∞ data for 2-methyl-1-butanol in water are lacking in the literature, they were also determined in this work. For each pentanol isomer, the compiled data were critically evaluated and together with the data measured in this work correlated with a suitable model equation p...

Temperature dependences of limiting activity coefficients and Henry's law constants for N-methylpyrrolidone, pyridine, and piperidine in water

Limiting activity coefficients ( γ 1 ∞ ) of N-methylpyrrolidone (NMP), pyridine, and piperidine in water were measured at several temperatures in the range from 333 K to 373 K. Three experimental techniques, namely Rayleigh distillation, differential distillation, and the method of circulation still, were employed for the purpose. A comprehensive review is further presented of experimental data on the limiting activity coefficients γ 1 ∞ , infinite dilution partial molar excess enthalpies ( H ¯ 1 E , ∞ ) , and heat capacities ( C ¯ p , 1 E , ∞ ) of these aqueous solutes. Additionally, to verify fragmentary literature information, solution heat capacity for NMP was also determined in this work using Picker flow microcalorimeter. For each solute, the compiled data were critically evaluated and together with the data measured in this work correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, a recommended thermodynamically consistent temperature dependence of γ 1 ∞ was established in the range from the melting point to the normal boiling point of water. Analogous recommendations were derived also for the temperature dependence of the Henry's law constants ( k H).

Temperature dependence of limiting activity coefficients and Henry’s law constants of cyclic and open-chain ethers in water

Limiting activity coefficients ( γ 1 ∞ ) of seven selected ethers (diethyl ether, tetrahydrofuran, tetrahydropyran, dimethoxymethane, 1,2-dimethoxyethane, 1,3-dioxolane, and 1,4-dioxane) in water were measured at several temperatures in the range from 273 to 373 K. Six experimental techniques were employed for the purpose. A comprehensive review is presented of experimental data on the limiting activity coefficients, infinite dilution partial molar excess enthalpies and heat capacities of these aqueous solutes. For each ether, the compiled data were critically evaluated and together with the data measured in this work correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, a recommended thermodynamically consistent temperature dependence of γ 1 ∞ of superior accuracy was established in the range from the melting point to the normal boiling point of water. Analogous recommendations were derived also for the temperature dependence of their Henry’s law constants ( K H ) . Variations of the infinite dilution thermodynamic properties of aqueous ethers with temperature and ether molecular structure are subsequently discussed. The performance of three group contribution approaches, namely the modified UNIFAC, and the methods of Cabani et al. and Plyasunov et al., to predict γ 1 ∞ for the aqueous ethers was tested and found quite unsatisfactory.

Temperature Dependence of Limiting Activity Coefficients, Henry's Law Constants, and Related Infinite Dilution Properties of Branched (C3 and C4) Alkanols in Water. Measurement, Critical Compilation, Correlation, and Recommended Data

Limiting activity coefficients ( ) of lower branched alkanols (2-propanol, 2-butanol, 2-methyl-1-propanol, and 2-methyl-2-propanol) in water were measured at several temperatures covering the range from the melting to the normal boiling point of water. Four experimental techniques (namely, headspace analysis, inert gas stripping, Rayleigh distillation, and the method of circulation still) were employed for the purpose. A comprehensive review is further presented of experimental data on the limiting activity coefficients ( ), infinite dilution partial molar excess enthalpies ( ), and heat capacities ( ) of these aqueous solutes. For each alkanol, the compiled data were critically evaluated and together with the data measured in this work correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, a recommended thermodynamically consistent temperature dependence of , , and of superior accuracy was established in the range from the melting point to the normal boiling point of water. In addition, by employing literature data on the respective residual properties of the pure alkanols, analogous recommendations were derived also for the temperature dependence of the Henry's law constants, hydration enthalpies, and hydration heat capacities. Variation of these various infinite dilution thermodynamic properties of aqueous branched alkanols with temperature and alkanol branching is briefly discussed.

Temperature Dependences of Limiting Activity Coefficients, Henry’s Law Constants, and Derivative Infinite Dilution Properties of Lower (C1–C5) 1-Alkanols in Water. Critical Compilation, Correlation, and Recommended Data

A comprehensive review is presented of experimental data on the limiting activity coefficients γ1∞, infinite dilution partial molar excess enthalpies H¯1E,∞ and heat capacities C¯p,1E,∞ of lower 1-alkanols (C1–C5) in water. For each alkanol, the compiled data are critically evaluated and correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, recommended thermodynamically consistent temperature dependences of γ1∞, H¯1E,∞, and C¯p,1E,∞ of superior accuracy are established in the range from the melting point to the normal boiling point of water. In addition, by employing literature data on the respective residual properties of the pure 1-alkanols, analogous recommendations are also derived for the temperature dependences of the Henry’s law constants, hydration enthalpies, and hydration heat capacities. Evolution of the various infinite dilution thermodynamic properties of aqueous 1-alkanols with temperature and homologous series is briefly discussed.

Temperature Dependence of Infinite Dilution Activity Coefficients in Octanol and Octanol/Water Partition Coefficients of Some Volatile Halogenated Organic Compounds

Infinite dilution activity coefficients and Henry's law coefficients have been measured for 11 halogenated C 1 to C 3 compounds in 1-octanol above room temperature using a gas-liquid chromatographic measurement method. Then, using our earlier data for these substances in water and a correlation relating the limiting activity coefficients of a substance in pure water and in pure 1-octanol to their octanol/water partition coefficients, these latter quantities have been computed. One conclusion from these measurements is that the limiting activity coefficients in octanol and the octanol/water partition coefficients of the halogenated compounds studied are only weakly dependent on temperature over the range from 25 to 50°C. Also, from these and our earlier data, we have estimated the infinite dilution partial molar excess enthalpies and excess entropies of these compounds in both 1-octanol and water.

A thermodynamic study of N-n-butylbenzamide solutions using gas-liquid chromatography

Using g.l.c., the activity coefficients at infinite dilution in the solvent N-n-butylbenzamide have been obtained for 14 solutes of varying saturation and polarity. The infinite dilution partial molar excess enthalpies and entropies of the solute have been calculated from the temperature dependence of the activity coefficients.