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.     

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.     

Vapour pressures and excess functions of N, N, N′, N′-tetramethylalkanediamine + cyclohexane. A group contribution study of the N---N proximity effect

The vapour pressuresof liquid cyclohexane + N, N, N′, N′-tetramethylalkanediamine, (CH₃)₂ N(CH₂)_uN(CH₃)₂ (u = 1,2) + cyclohexane mixtures were measured by a static method between 303.15 and 343.15 K at 10 K intervals. The excess molar enthalpies at 303.15 K were also measured.

The molar excess Gibbs energies, calculated from the vapour-liquid equilibrium data, and the molar excess enthalpies compare satisfactorily with group contribution (DISQUAC) predictions.

The proximity effect of N atoms produces a regular decrease of the interactional parameters.     

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.     

Simultaneous description of vapor-liquid equilibrium and excess enthalpies for methanol and ethanol binary mixtures with propanal

Four different formulations of the thermodynamic properties of alcohol + unassociated active component mixtures have been used to describe simultaneously the vapor-liquid equilibrium and excess enthalpies of the methanol + propanal and ethanol + propanal mixtures. The equations used are based on a continuous linear association model proposed by Kretschmer and Wiebe and extended by Nagata and coworkers to include alcohol + unassociated active component mixtures. The equations are severely tested in this attempt to describe the highly non-ideal mixtures formed by an alcohol and propanal. Results obtained are more accurate than those previously reported for the Lattice-Fluid and the Lattice-Fluid Associated Solution models.     

Thermodynamic properties of binary mixtures containing aldehydes. II. Liquid-vapor equilibria in normal or branched alkanal + normal alkane mixtures: Analysis in terms of a quasichemical group-contribution model

Recent liquid-vapor equilibrium data for three alkanal + n-alkane mixtures are examined on the basis of the surface-interaction version of the quasichemical group-contribution theory used in Part I to correlate and predict excess enthalpies and excess Gibbs energies for such mixtures. The predictions prove to be accurate to better than 10%. Using the new data, revised interaction parameters are proposed for the estimation of liquid-vapor equilibrium for normal or branched alkanal + normal alkane mixtures.     

Thermodynamic functions for the systems 1-butanol, 2-butanol,andt-butanol + cyclohexane

The following properties of mixtures of the butanols with cyclohexane were measured over the whole range of composition: 1-butanol+cyclohexane and 2-butanol+cyclohexane; excess enthalpies at 15, 25, 35 and 45°C, excess volumes at 25 and 45°C, activity coefficients and excess Gibbs free energies at 45°C. 2-Methylpropan-2-ol (tertiary butanol)+cyclohexane; excess enthalpies at 26, 35, and 45°C, excess volumes at 26 and 45°C, activity coefficients and excess Gibbs free energies at 45°C. From these data, activity coefficients at the temperatures of the excess enthalpy measurements below 45°C have been computed, as a source of test data for models of alcohol association through hydrogen bonding.     

DISQUAC predictions of phase equilibria,molar and standard partial molar excess quantities for 1-alkanol+cyclohexane mixtures

Literature data for phase equilibria: vapor-liquid VLE, liquid-liquid LLE, and solid-liquid SLE; molar excess Gibbs energies G ^E , molar excess enthalpies H ^E ; activity coefficients _i and partial molar excess enthalpies H _i ^E,o at infinite dilution for 1-alkanol (1)+cyclohexane (2) mixtures are examined by the DISQUAC group contribution model. For a more sensitive test of DISQUAC, the azeotropes, obtained from the reduction of the original isothermal VLE data, are also examined for systems characterized by hydroxyl, alkane and cyclohexane groups. The alkane/cyclohexane and alkane/hydroxyl interaction parameters have been estimated previously. The cyclohexane/hydroxyl interaction parameters are reported in this work. The first dispersive parameters increase regularly with the size of the alkanol; from 1-octadecanol they are constant; an opposite behavior is encountered for the third dispersive parameters, which are constant from 1-dodecanol. The second dispersive parameters decrease as far as 1-propanol and then increase regularly; from 1-octadecanol they are constant. The quasichemical parameters are equal to those for the alkane/hydroxyl interactions. Phase equilibria, the molar excess functions, and activity coefficients at infinite dilution are reasonably well reproduced. Poor results are found for H _i ^E,o and DISQUAC predictions for H _i ^E,o are strongly dependent on temperature.     

Total vapour pressure and excess Gibbs energy for binary mixtures of 1,1,2,2-tetrachlorethane or tetrachloroethene with cyclohexane at nine temperatures

Vapour pressures of (cyclohexane + 1,1,2,2-tetrachloroethane (TCANE)) or (cyclohexane + tetrachloroethene (TCENE)) mixtures at nine temperatures between 283.15 and 323.15 K were measured by a static method. The reduction of the vapour pressures to obtain activity coefficients and excess molar Gibbs energies was carried out by fitting the vapour-pressure data to the Redlich–Kister polynomial according to Barker’s method. A comparative analysis about the thermodynamic behaviour of both systems is performed, taking into account the resonance effect in tetrachloroethene. For 1,1,2,2-tetrachloroethane + cyclohexane mixtures, we have tested the DISQUAC model observing that reproduces satisfactorily the G^E experimental values at all temperatures.     

Thermodynamics of weak interactions: excess enthalpies and excess Gibbs free energies of mixing

Excess enthalpies of chloroform + n-hexane, bromoform + n-hexane, bromoform + pyridine and bromoform + benzene and excess Gibbs free energies of mixing for bromoform + pyridine, chloroform + pyridine, bromoform + n-hexane, chloroform + n-hexane and bromoform + benzene have been determined at 308.15 K and the same factors have been examined for Barker's theory to understand the magnitude and nature of various interactions between the components of these mixtures.     

Prediction of vapor-liquid equilibrium from excess enthalpy data for binary ether +n-alkane or cyclohexane mixtures

Vapor liquid equilibrium (VLE) is successfully predicted from excess enthalpy H^E data for binary ether + n-alkane or cyclohexane mixtures. Parameters for the continuous linear association model (CLAM) and for the UNIQUAC Model for the excess Gibbs energy G^E were determined from H^E data measured at a low temperature (ambient temperature). These parameters are used to predict VLE data at low and high temperatures. The dependence of the accuracy of predictions on the set of H^E data chosen to evaluate the parameters and on the model for G^E are discussed.     

Thermodynamics of Organic Mixtures Containing Amines. II. Excess Molar Volumes at 25°C for Methylbutylamine + Alkane Systems and Eras Characterization of Linear Secondary Amine + Alkane Mixtures

Excess molar volumes, at 25°C and atmospheric pressure for methylbutyl amine + n-hexane; + cyclohexane; + n-octane; n-decane; + n-dodecane; + n-tetradecane, or + n-hexadecane systems are reported from densities measured with a vibrating-tube densimeter. The excess functions, molar enthalpy, and volume, for linear secondary amine + n-alkane systems are discussed in terms of interactional and structural effects. In addition, these solutions, which include amines from dimethyl to dioctylamine, are studied in the framework of the ERAS model. The corresponding ERAS parameters are reported. The agreement between experimental data and ERAS results is good for excess enthalpies, excess Gibbs energies, and excess molar volumes. The larger discrepancies are found for the excess volumes when strong free-volume effects are present in the investigated mixtures. The variation with temperature of the thermodynamic properties is well described by ERAS.