Association model of fluids. Simultaneous representation of excess Gibbs energies and excess enthalpies for liquid mixtures with alkanols

The binary excess Gibbs energies and excess enthalpies of liquid mixtures of alkanols and hydrocarbons, acetone, methyl acetate, acetonitrile, organic acid, etc., are simultaneously correlated with a new association model whose equilibrium constants are defined in terms of the modified segment fractions of chemical species. The model predicts ternary vapor-liquid, liquid-liquid equilibria and excess molar enthalpies of those mixtures well using only binary parameters.     

Thermodynamics of mixtures containing bromoalkanes. I. Estimation of DISQUAC interchange energy parameters for 1-bromoalkane + n-alkane mixtures. Comparison with other haloalkanes

The experimental literature data on vapor-liquid equilibria (VLE), excess molar Gibbs energies, molar excess enthalpies and activity coefficients and partial molar excess enthalpies at infinite dilution of 1-bromoalkane + n-alkane mixtures are interpreted in terms of the DISQUAC group contribution model. The model reproduces fairly well most of the experimental data using a pair (Gibbs energy and enthalpy) of constant quasichemical interchange energies and a pair (Gibbs energy and enthalpy) of dispersive interchange energies. The dispersive interchange energies of bromoethane and of the higher 1-bromoalkanes are constant, but larger than for bromomethane. Several sets of VLE data are likely to be in error. Characteristic discrepancies between calculated and experimental values are observed in mixtures containing molecules of widely different sizes. The dispersive interchange energies of 1-chloro, 1-bromo- and 1-iodoalkanes increase in the order Cl < Br < I, as do the differences between the cohesive energy densities of haloalkanes and n-alkanes. The quasichemical interchange energies decrease in the order Cl > Br > I, almost linearly with the increasing relative surface of the halogen groups. Tentative values for the interchange energies of 1-fluoroalkanes + n-alkanes were estimated from the few available experimental data.     

Measurement and correlation of excess molar enthalpies for the partially miscible systems 2-butanone+water and methanol+hexane

The excess molar enthalpies of the systems 2-butanone+water and methanol+hexane which show limited miscibility were measured at 283.15–298.15 K using a flow microcalorimeter. The experimental data were correlated using three local-composition (LC) models (NRTL, modified Wilson and modified EBLCM). These models were also used to predict the liquid–liquid equilibria for both systems with the parameters obtained from the excess enthalpy data.     

Thermodynamics of complex formation in chloroform-oxygenated solvent mixtures

Complex formation equilibria in binary mixtures of chloroform with dipropyl ether (PE), diisopropyl ether (IPE), methyl tert-butyl ether (MBE), tetrahydrofuran (THF). 1,4-dioxane (DOX), acetone (AC), and methyl acetate (MA) have been analyzed in detail using several association models. Vapor-liquid equilibria, excess enthalpy and excess heat capacity data for these mixtures have been correlated using a multiproperty global fitting procedure. The thermodynamic properties for chloroform +PE, +IPE, +MBE, +AC, and +MA are best correlated using the ideal association model while for chloroform +THF and +DOX the best model is an athermal solvation model where the Flory-Huggins expression for the species activity coefficients is considered. The model parameters, i.e., the equilibrium constant, enthalpies and heat capacities of complexation, were found to be reliable, well representing the chloroform-oxygenated solvent H-bonded complexes. A detailed discussion is given on the test proposed by McGlashan and Rastogi to decide whether the solution contains only 11 complexes or 21 complexes as well. The complex formation equilibria in chloroform mixtures is compared to those previously examined for halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) mixed with the same oxygenated solvents. It was found that the H-bonds formed by halothane are stronger than those formed by chloroform.     

Liquid—liquid—vapor phase equilibria behavior of certain binary ethane + n-alkylbenzene mixtures

The liquid—liquid—vapor loci for the binary mixtures ethane + n-nonylbenzene, ethane + n-decylbenzene and ethane + n-undecylbenzene were experimentally studied. The pressure, temperature, and compositions and molar volumes of the liquid phases are reported along the loci. n-Nonylbenzene was found to be the first member of the n-alkylbenzene homologous series to exhibit liquid—liquid—vapor immiscibility with ethane. For the three alkylbenzenes studied, the liquid—liquid—vapor loci have the same type of behavior: they extend from a lower critical end point (LCEP) to an upper critical end point (K-point).     

Thermodynamics of complex formation in ternary liquid mixtures containing acetonitrile

Vapor—liquid and liquid—liquid equilibria and excess enthalpies for ternary mixtures formed from acetonitrile, benzene, n-heptane, toluene, and carbon tetrachloride are successfully correlated with a modified version of the associated solution theory proposed by Lorimer and Jones in 1977, which assumes two types of self-association for acetonitrile and binary complexes between acetonitrile and unsaturated hydrocarbons and does not include any ternary parameters.     

Thermodynamics of liquid mixtures containing a very strongly polar compound: Part 6. DISQUAC characterization of N,N-dialkylamides

Systems of N,N di(n-alkylamides) (hereafter, N,N-dialkylamides) with alkane, benzene, toluene, 1-alkanol or 1-alkyne have been investigated in the framework of the DISQUAC model. The corresponding interaction parameters are reported. They change regularly with the molecular structure of the mixture components. This variation is similar to those encountered when treating other systems in terms of DISQUAC. The model describes consistently a whole set of thermodynamic properties: liquid–liquid equilibria (LLE), vapor–liquid equilibria (VLE), solid–liquid equilibria (SLE), molar excess Gibbs energies (G^E), molar excess enthalpies (H^E), molar excess heat capacities at constant pressure (C_P^E), partial molar excess properties at infinite dilution, enthalpies and heat capacities. The model also provides good results for the Kirkwood–Buff integrals and for the linear coefficients of preferential solvation. For ternary systems, DISQUAC predictions on VLE and H^E, obtained using binary parameters only, are in good agreement with the experimental data. A short comparison between DISQUAC and Dortmund UNIFAC results is shown. DISQUAC improves UNIFAC results on H^E and C_P^E, magnitudes which strongly depend on the molecular structure. The investigated mixtures behave similarly to those characterized by thermodynamic properties which arise from dipolar interactions. Association/solvation effects do not play, as a whole, an important role in the studied systems. This may explain that the ERAS model fails when representing the thermodynamic properties of dimethylformamide + 1-alkanol mixtures.     

Excess enthalpies of the ternary mixtures: tetrahydrofuran + (diisopropyl ether or 2-methyltetrahydrofuran) + n-heptane at 298.15 K

Excess molar enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for the ternary mixtures (tetrahydrofuran + diisopropyl ether + n-heptane) and (tetrahydrofuran + 2-methyltetrahydrofuran + n-heptane). Smooth representations of the results are described and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. The latter are compared with diagrams obtained when the model of Liebermann and Fried is used to estimate the excess enthalpies of the ternary mixtures from the physical properties of the components and their binary mixtures.     

Excess enthalpies of binary solvent mixtures of N-methylacetamide with aliphatic alcohols

The molar excess enthalpies H _m ^E of binary solvent mixtures of N-methylacetamide with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and t-butanol have been measured with a flow microcalorimeter at 40°C. The excess enthalpies are negative for methanol and positive for the other alcohols over the whole composition range, except for t-butanol which exhibits a sigmoid curve with a deep minimum at low mole fractions of the amide. The values for the primary alcohols increase in the order methanol < ethanol < 1-propanol < 1-butanol. The partial molar excess enthalpies have also been evaluated. Intermolecular interactions in these mixtures are discussed through comparison of the results with those for the corresponding binary mixtures of N,N-dimethylacetamide.     

Excess enthalpies of binary mixtures of 2-ethyl-1-butanol with hexane isomers

Molar excess enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for binary mixtures of 2-ethyl-1-butanol with the five isomeric hexanes. The results are compared with previously published excess enthalpies for mixtures of 1-hexanol and 2-methyl-1-pentanol with the same hexane isomers.     

Excess molar enthalpies for binary mixtures of different amines with water

The isothermal excess molar enthalpies for binary mixtures of different amines with water were measured with a C-80 Setaram calorimeter. The experimental results indicate that the excess molar enthalpy is related to the molecular structure. The experimental excess molar enthalpies were satisfactorily fitted with the Redlich–Kister equation. They were also used to test the suitability of the NRTL model, and the deviations are a little larger than the R–K equation.     

Excess enthalpies of binary solvent mixtures of 1-butanol and 2-methyl-2-propanol with aniline,N-methylaniline,and N,N-dimethylaniline

The excess molar enthalpies of binary solvent mixtures of 1-butanol and 2-methyl-2-propanol with aniline, N-methylaniline, and N,N-dimethylaniline were measured with a flow microcalorimeter at 40°C. The excess enthalpies are positive for all the systems, and smaller for the mixtures of 1-butanol than the corresponding mixtures of 2-methyl-2-propanol. With respect to the anilines, the values increase in the order aniline < N-methylaniline < N,N-dimethylaniline.     

Excess molar enthalpies of the ternary mixtures: (diisopropyl ether or 2-methyltetrahydrofuran) + cyclohexane + n-heptane at 298.15 K

Microcalorimetric measurements of excess molar enthalpies, at 298.15 K, are reported for the two ternary systems formed by mixing either diisopropyl ether or 2-methyltetrahydrofuran with binary mixtures of cyclohexane and n-heptane. Smooth representations of the results are presented and used to construct constant excess molar enthalpy contours on Roozeboom diagrams. It is shown that useful estimates of the ternary enthalpies can be obtained from the Liebermann and Fried model, using only the physical properties of the components and their binary mixtures.     

Excess enthalpies of binary solvent mixtures of 2-butanone with aliphatic alcohols

The molar excess enthalpies of binary solvent mixtures of 2-butanone with methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-methyl-2-propanol have been measured with a flow microcalorimeter at 313.15 K. The excess enthalpies are positive over the whole composition range for all alcohols studied. The values for the primary alcohols increase with the length of the alkyl chain of the alcohol. The values for the secondary and the tertiary alcohol are slightly greater than those for the primary analogues. The partial molar excess enthalpies have also been evaluated. The results are discussed in terms of intermolecular interactions in the mixtures.     

Thermodynamics of binary mixtures containing aldehydes. excess enthalpies of n-alkanals + benzene and + tetrachloromethane mixtures

Molar excess enthalpies H^E have been measured as a function of mole fraction at atmospheric pressure and 298.15 K for the binary liquid mixtures of ethanal, propanal, butanal and pentanal + benzene or + tetrachloromethane. The results show that the excess enthalpies decrease with increasing the n-alkanal chain length, with negative values for n-pentanal.