Solvation behaviour of silver(I) iodate in methanol—acetonitrile and ethanol—acetonitrile mixtures

The solvation behaviour of silver(I) iodate in methanol—acetonitrile (AN) and ethanol—acetonitrile mixtures has been studied at 30°C by solubility and emf measurements. The solubility of the salt increases with the addition of AN and passes through a maximum at X_AN = 0.3 and 0.6 in the case of MeOH-AN and EtOH-AN mixtures, respectively, and then decreases with further addition of AN. The transfer free energy of silver ion decreases while that of iodate ion increases with the addition of AN in both the solvent mixtures. The solvent transport number, Δ of AN is positive with a maximum at X_AN = 0.45 (Δ = 0.45 (Δ = 5.4) and at X_AN = 0.55 (Δ = 2.4) in the case of MeOH-AN and EtOH-AN mixtures, respectively. These results have been interpreted in terms of the heteroselective solvation of the salt, the silver ion being preferentially solvated by AN and the iodate ion by the amphiprotic solvent component in these mixtures.     

Vapour—liquid equilibrium of the system benzene + cyclohexane + 1-propanol at 760 mm Hg

Arce, A., Blanco, A. and Tojo, J., 1986. Vapour—liquid equilibrium of the system benzene + cyclohexane + 1-propanol at 760 mm Hg. Fluid Phase Equilibria, 26: 69–81.Vapour—liquid equilibrium data for the mixture benzene + cyclohexane + 1-propanol at a constant pressure of 760 mm Hg have been determined experimentally and predicted using the group contribution methods UNIFAC and ASOG and the NRTL, UNIQUAC and Wilson equations (with correlation parameters obtained from data for the corresponding binary mixtures). The various predictions are compared and evaluated in the light of the experimental results.     

Liquid–liquid equilibrium behavior of tetrabutylammonium bromide,benzene, and water mixture

Tetrabutylammonium bromide (QBr) is a weak organic salt and used as a phase-transfer catalyst in phase-transfer catalytic reaction producing the desired product of benzyl bromide in the organic phase. The distribution of QBr between the organic phase (benzene is the organic phase solvent) and the aqueous phase is the important factor influencing benzyl bromide yield. In this study, the liquid–liquid equilibrium of benzene, water, and QBr ternary mixture were measured at 318.15, 328.15, and 338.15 K, respectively. The experimental results exhibited that the solubility of QBr is very large in this heterogeneous liquid mixture and the amount of aqueous phase increases whenever more QBr was added at constant temperature. The concentration of QBr in aqueous phase decreased with the increasing temperature. The organic phase composition did not vary obviously since the solubilities of water and QBr in benzene are very low. An empirical parameter was introduced to represent the degree of dissociation of QBr in solvent while the experimental data were correlated since it is very difficult to measure the degree of dissociation of QBr attributed to the partial dissociation of a weak organic salt. Finally, the experimental data were correlated with the NRTL model of Renon and Prausnitz taking account ion–molecule and molecule–molecule interactions.     

Liquid—liquid equilibrium in methanol + gasoline blends

An investigation has been carried out to study the limited miscibility of methanol and gasoline blends over the temperature range −20 to 20°C. Two liquid phases in equilibrium were analysed by mass spectrometric methods and their composition reported, in addition to the methanol content, in terms of six principal classes of hydrocarbons. Liquid—liquid equilibrium was predicted using the UNIFAC group contribution model. In liquidliquid equilibrium calculations, gasoline was represented by a set of model compounds. The number of the different groups that comprise each model molecule was determined using the result of a distillation analysis and the paraffin—naphthene—aromatic composition. Estimation of conjugate phase composition using the UNIFAC model is reasonable at temperatures above 0°C. To describe correctly the limited miscibility of methanol+gasoline blends over the whole temperature range studied, we found that ‘specific’ UNIFAC interaction parameters were necessary.     

Molecular thermodynamics of salt effect in vapor–liquid equilibrium of ethanol–water systems

Scaled particle theory was used to derive a general expression for the salt effect parameter, K, of isobaric vapor–liquid equilibrium for ethanol–water-1-1 type electrolytic systems, which appears in the Furter equation. This expression was essentially a sum of two terms: 1, the hard sphere interaction term calculated by Masterton–Lee's equation, 2, the soft sphere interaction term calculated by Y. Hu's molecular thermodynamical model, in which the diameters of nacked ions were replaced by that of solvated ions, the solvation coefficients (i.e., in the radio of the latter to the former) were taken to be adjustable parameters, their magnitude implies the ionic solvation rules. A correlation equation for the local dielectrical constant around central ions with liquid concentration was obtained by mapping out experimental points. The calculated salt effect parameters of 9 ethanol–water-1–1 type electrolytic systems were in good agreement with the literature values within the wide range of liquid concentration.     

Perfluorodecaline/hydrocarbon systems prediction and correlation of liquid—liquid equilibrium data

Bernardo Gil, M.G. and Soares, L.J.S., 1986. Perfluorodecaline/hydrocarbon systems prediction and correlation of liquid—liquid equilibrium data. Fluid Phase Equilibria, 25: 291–302.Experimental binary, ternary and quaternary liquid-liquid equilibrium data for systems containing perfluorodecaline (PFD) and some hydrocarbons were determined.Binary NRTL, UNIQUAC and UNIFAC parameters were obtained, from the binary, the ternary and the quaternary experimental data: for the calculation of parameters from binary data a Newton-Raphson technique was used and the parameters so obtained—for each temperature (T)-were linearly correlated with T and 1/T. Predicted binary, ternary and quaternary data were then compared with the experimental results; a Nelder-Mead method was used for the calculation of the binary parameters from ternary tie-line data.UNIFAC group parameters for the interaction CH₂/CF₂ and CHCH₂/CF₂ were obtained.Attempts were made, and are discussed, to: correlate UNIFAC parameters with the number of carbon atoms and temperature; obtain a set of NRTL and UNIQUAC parameters yielding the overall best fit for the systems under consideration.     

Ternary phase equilibrium studies of the water—ethanol—1,8-cineole system

Ternary liquid—liquid equilibrium data at 25°C were obtained for the water—ethanol—1,8-cineole system, 1,8-cineole being the main component of eucalyptus oil. This study formed one aspect of a project utilizing solar energy stored in plants as liquid fuel components. Experimental results confirmed the absence of phase separation problems in the use of this system as a liquid fuel. The tie-line data for the system were well correlated by the methods of Hand and Othmer—Tobias. The solubility of 1,8-cineole in water was determined over a range of temperatures.     

The influence of the temperature on the liquid–liquid equilibrium of the ternary system 1-pentanol–ethanol–water

Liquid–liquid equilibrium data for the ternary system 1-pentanol–ethanol–water have been determined experimentally at 25, 50, 85 and 95°C. These results have been correlated simultaneously by the uniquac method obtaining two sets of interaction parameters: one of them independent of the temperature and the other with a linear dependence. Both sets of parameters fit the experimental results well.     

Determination of vapor—liquid equilibrium diagrams of multicomponent systems

A method for the determination of vapor–liquid phase diagram structure of five-component systems based on the analysis of types and Poincare indexes of singular points of the geometric scan and full structure of the concentration simplex is proposed. Validity of the proposed method was demonstrated by vapor–liquid equilibrium modeling in five-component mixtures: ethanol + water + toluene + butanol + chlorbenzene and acetone + chloroform + ethanol + cyclohexane + water.     

Vapor—liquid equilibrium studies for the carbon dioxide—methanol system

Experimental vapor—liquid equilibrium measurements of carbon dioxide and methanol have been conducted from 230 K (−43.15°C) to 330 K (56.85°C) at pressures to the very vicinity of the critical states. The consistency of the data sets are examined and compared to literature values.Unlike the methane—methanol system, which exhibits two liquid phases at low temperatures, the carbon dioxide—methanol system exhibits complete liquid phase miscibility. Accordingly, the effects of critical behavior on the vapor liquid equilibria behavior begin to manifest themselves at much lower pressures.     

Liquid–liquid phase equilibrium of methanol + ethylbenzene + isooctane + ethanol system at 303 K

The phase equilibrium data for methanol + ethanol + isooctane systems were obtained at 303.15 K. Data for methanol + ethylbenzene + isooctane system were taken from literature. The effect of ethanol addition on the system equilibrium was investigated at the same temperature. The distribution curves for ternary and quaternary system was analyzed. The experimental results for ternary systems were correlated with UNIQUAC and NRTL equations. For the ternary systems studied here, the NRTL equation is more accurate than the UNIQUAC. The equilibrium data for the three ternary systems were used to determine interactions parameters for the UNIQUAC equation. For the quaternary system, the experimental data can be fitted more accurately to UNIQUAC equation than by the UNIFAC method.     

Phase equilibrium in the system water–acetonitrile–cyclohexene–cyclohexanone

Phase equilibrium in the water–acetonitrile–cyclohexene–cyclohexanone quaternary system and in its binary and ternary constituents was studied using experimental and calculation methods. The parameters were determined for the NRTL equation that adequately describes liquid–vapor, liquid–liquid–vapor, and liquid–liquid–liquid equilibria. The evolution of the three-phase splitting region inside the concentration tetrahedron was studied on the basis of the obtained model, and its transformation into the two-phase region through the critical node was shown. Thermodynamic analysis involving topological representation for the diagram of the phase equilibrium in a quaternary system was performed, and schemes for the complete separation of the reaction mixture were proposed.     

Thermodynamic study of the vapor–liquid equilibrium (VLE) data of the mixture formed by diethylenimide oxide with benzene

The thermodynamic evaluation of the experimental vapor?Cliquid equilibrium (VLE) data obtained at 760?mmHg in a recirculatory still, is presented for the binary system formed by diethylenimide oxide with benzene. The experimental VLE data were checked for thermodynamic consistency and reduced to the binary parameters calculated from three activity coefficients models.     

Effect of nonvolatile solute on vapor–liquid equilibrium at fixed liquid composition

The influence of some nonvolatile solutes on boiling points of two azeotropic mixtures (1-propanol–water and methanol–tetrahydrofuran systems) was determined by means of isobaric vapor–liquid equilibrium experiments. A basic thermodynamic equation of nonvolatile solute effect on vapor–liquid equilibrium at fixed liquid composition was derived. Based on the theoretical analysis about the equation, two criterions of universal significance were obtained: (1) when a little nonvolatile solute dissolves in a binary liquid mixture with constant composition, if the vapor composition of less volatile component is increased the boiling point must be elevated at given pressure or the vapor pressure must be depressed at given temperature; (2) when a little nonvolatile solute dissolves in an azeotropic mixture, any kind of nonvolatile solute always causes the elevation of boiling point at given pressure or the depression of vapor pressure at given temperature irrespective of the variation of vapor composition. Verifying through the experiments of this paper and lot of the relevant experimental data in the literature, all of the experimental results were in agreement with both criterions without exception.     

Friedel-Crafts polymers—3. Products of the copolymerization of p-di(chloromethyl) benzene with benzene

This paper represents a further step towards the precise characterization of Friedel-Crafts polymers with the object of relating thermal stability to chemical structure.By the use of preparative gel permeation chromatography, it has been possible to separate the early products of the SnCl₄ catalysed copolymerization of p-di(chloromethyl) benzene with benzene. All products with mol. wts. up to 800 have been identified by the combined application of i.r., NMR and mass spectrometry; their formation has been accounted for. These results have allowed a number of generalizations to be made about the main course of the overall polymerization. From the rate curves which have been obtained for each of the products, it should be possible to apply computer techniques and to determine the rate constants for their formation.     

Isobaric vapor–liquid–liquid equilibrium and vapor–liquid equilibrium for the system water–ethanol-1,4-dimethylbenzene at 101.3 kPa

An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer has been used to determine vapor–liquid (VLE) and vapor–liquid–liquid (VLLE) equilibria. Consistent data have been obtained for the ternary water + ethanol + p-xylene system at 101.3 kPa for temperatures in the range of 351.16–365.40 K. Experimental results have been used to check the accuracy of the UNIFAC, UNIQUAC and NRTL models in the liquid–liquid region of importance in the dehydration of ethanol by azeotropic distillation.     

Solvation thermodynamics of benzene,nitrobenzene, and aniline in water–acetonitrile mixtures

The enthalpies of dissolution of benzene, nitrobenzene, and aniline in water–acetonitrile mixtures are determined via calorimetry. The concentration dependences of the standard enthalpies of solvation of solutes are calculated. It is found that the concentration dependences of the standard enthalpies of solvation pass through maxima. The height of the observed maxima is shown to depend largely on the nature of the substituent. In the presence of a hydrophilic amino group capable of forming strong hydrogen bonds with water molecules, the value of a maximum falls; in the presence of a nitro group, it rises. The enthalpy parameters of pair interaction between molecules of water and benzene and its derivatives are calculated.