Excess molar volumes ofn-alkanes-thiophene mixtures at 25°C

The excess molar volumes of binary mixtures of n-hexane, n-octane, n-decane, n-dodecane, and n-hexadecane with thiophene have been measured at 25°C over the whole mole fraction range. All the experimental values, except those for n-hexane-thiophene in the thiophene rich region, are positive. The Flory theory was used to determine the influence of molecular contact sites on the excess volumes. A new calculation procedure has been suggested by introducing a new parameter S. This method greatly improved the theoretical results.     

Excess volumes and excess enthalpies of cyclohexanone with alkanes,benzene, toluene and tetrachloromethane at 298.15 K

Excess volumes and excess enthalpies have been measured for binary liquid mixtures of cyclohexanone with n-hexane, n-heptane, 2,2,4-trimethylpentane, benzene toluene and tetrachloromethane at 298.15 K. The results have been discussed in terms of the difference in molecular shape and specific interactions between unlike molecules. The Prigogine—Patterson—Flory equation of state theory has been used to evaluate the free volume and interactional contributions of the excess properties, and to predict excess volumes and excess enthalpies. The calculated values of V^E and H^E are in qualitative agreement with the experimental data in all the systems.     

Excess thermodynamic properties of binary mixtures of n-Alkanes with cycloalkanones

Molar excess enthalpies of the systems cyclopentanone/n-alkanes and cyclohexanone/n-alkanes at 298.15 K were determined by direct calorimetric measurements. Molar excess volumes of cyclopentanone and cyclohexanone/n-alkanes were determined at 298.15 and 308.15 K and of cycloheptanone/n-alkanes at 298.15 K by dilatometric measurements of volumes of mixing. The excess thermodynamic properties for a particular cycloalkanone increase with the chain length of the n-alkane, while for a given n-alkane, excess properties decrease as the size of the cycloalkanone increases.     

Volumes of mixing of n-octylacetate + n-alkanes: an interpretation in terms of the Prigogine-Flory-Patterson theory

The results of measurements of molar excess volumes V^E at 303.15 K over the whole mole fraction range for eight mixtures: n-octylacetate + n-hexane; +n--heptane; + n-octane; +nn-nonane; + n-decane; +nn-dodecane; + n-tetradecane and + n-hexadecane are presented. The experimental values of V^E show a regular pattern of behaviour for the eight sets of binary mixtures. The magnitude of V^E for this class of mixtures decreases as the n-alkane chain-length decreases. In order to explain the observed behaviour, the Prigogine-Flory-Patterson theory is used to predict the total V^E and the three different contributions to V^E. Agreement between the theoretical and experimental V^E is reasonable for the eight systems     

Volumes of mixing of pyridine bases withn-alkanes: Comparison with the prigogine-flory-patterson theory

The excess molar volumes of binary mixtures pyridine and -picoline + C₆–C₁₀ n-alkanes have been measured at 25°C over the whole composition range. For pyridine + n-hexane and + n-heptane and also -picoline + n-hexane and n-heptane V ^E has an S-shaped behavior and is positive at low concentrations of the base. For the systems pyridine + n-octane + n-nonane + n-decane and -picoline + n-octane, n-nonane, and n-decane V ^E is positive. The Prigogine-Flory-Patterson theory has been fitted to our results.     

正丁醇、乙酸乙酯、正己烷的二元及三元体系的超额焓测量和关联

用等温稀释量热计测定了正己烷+正丁醇、正己烷+乙酸乙酯二元体系在303.15K、308.15K及正丁醇+乙酸乙酯+正己烷三元体系在303.15K的超额焓,用Kretschrner-Wiebe理论组合UNIQUAC方程所得数学模型对二元体系在303.15K的超颠焓进行了关联,并预测了所测三元体系在303.15K的超额焓,预测结果与实验值比较,平均偏差为6％。     

Volumetric,acoustic, optical and spectroscopic studies of binary mixtures of the ionic liquid, 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide and diethyl carbonate

The properties, density, speed of sound and refractive index of ‘IL’ [Bmim][NTf2], diethyl carbonate and their binary mixtures are measured over the whole composition range as a function of temperature between 303.15 and 323.15 K at atm. pressure. These values are used to calculate the excess molar volumes, excess partial molar volumes, partial molar volumes at infinite dilution, excess isentropic compressibility, free length, speeds of sound and isobaric thermal expansion coefficient for the mixture. Various rules were used to predict the refractive indices and the data have been compared with the experimental results. These excess properties are fitted to the Redlich–Kister type equation to obtain the binary coefficients and the standard deviations. A qualitative analysis of these parameters indicates strong intermolecular interactions and the interaction increases with the increase in temperature. This was further supported by IR spectroscopy. In addition, analysis of data of the mixture was done through the Prigogine–Flory–Patterson theory.     

Upper and lower critical solution temperatures in polybutadiene-alkane systems : Effect of the surface-to-volume ratio of the polymer

Cloud point curves (CPC) have been measured for 1–4 cis polybutadiene (M_r = 40,000–830,000) in n-hexane, 2-methyl-hexane, 2,2,3 trimethylbutane and 2,2,4 trimethylpentane. These four systems show upper and lower critical solubility temperatures which approach one another as the molecular weight increases. An hourglass-shaped CPC is found for two systems. The CPC are found to be much more dependent on polymer concentration than is usual. Calculated (Prigogine, Patterson, Flory theories) and experimental critical temperatures, critical volumes and shapes of the CPC are in much better agreement for these systems than for other systems involving polystyrene, polyisobutylene or polybutene-1. Analysis of these results with those for other systems in the literature indicates the importance of the surface-to-volume ratio s of the polymers. A small value of s = s₂/s₁ (0·5–0·8) for thick polymer chains improves the calculated value of the critical temperature while s = 1 is quite good for thin polymer chains such as polybutadiene and polyethylene.     

Molar and Partial Molar Excess Volumes of Benzene in Methyl Ester Solutions at 25°C

Molar and partial molar excess volumes of mixtures of benzene with several methyl esters (from methanoate to decanoate) were determined, over the whole concentration range, at 25°C and atmospheric pressure from experimental densities and correlated by a suitable equation. The applicability of the Flory and Priggogine–Flory–Pattersort models for predicting molar excess volumes is tested. The calculated values with Flory and Priggogine–Flory–Patterson are similar and agree poorly with the experimental data.     

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.     

Correlation of the prigogine-flory theory with isothermal compressibility and excess enthalpy data for benzene +n-alkane mixtures

Isothermal compressibilitiesκ _T for benzene + n-alkane systems at 25, 35, 45, and 60°C have been used to check the Prigogine-Flory theory using the van der Waals and Lennard-Jones potentials in order to study the energy-volume dependence. The Flory interaction parameter χ₁₂ has also been calculated for those set of systems at four temperatures. The variation of χ₁₂ with the number of carbon atoms in the n-alkane was studied. Three excess functions have been obtained from χ₁₂ for the equimolecular mixture: (?V ^E/?p)_T which is related toκ _T ^E , the excess enthalpy H ^E , and the excess volume V ^E . Except for H ^E theoretical predictions using a Lennard-Jones potential are in good agreement with the experimental data. A similar treatment has been performed for the same set of systems but using H ^E data at 25°C. The theory, using a van der Waals potential, predicts correctly the variation of the three excess functions with the chain length of the n-alkane but using a Lennard-Jones potential results in better agreement for the order in the magnitude of these excess functions.     

Excess volume of mixing and equation of state theories

Equation-of state theories of Flory and of Sanchez and Lacombe describe both enthalpy and volume of mixing of binary systems using single component properties and only one binary parameter X₁₂. We have evaluated this parameter from literature enthalpy data for numerous mixtures of two aromatic hydrocarbons, of alkanes with aromatic compounds, and of alkanes with carbonyl compounds. We have used this X₁₂ for calculation of excess volumes and compared the results with our previously measured experimental data. The agreement was fair for mixtures of two nonpolar components. Nevertheless, mixtures containing either cyclohexane or benzene displayed anomalies that could be traced to special packing of molecules in these compounds when pure. For mixtures of carbonyl compounds with alkanes, the theories predicted the qualitative trends correctly, but the quantitative agreement was rather poor. These results tend to support a model in which the enthalpy(cohesive energy) is inversely proportional to volume (as in the theories considered) only for dispersive interaction. When polar-polar interactions are involved, the dependence of excess volume on the excess enthalpy is much weaker.     

Excess Molar Enthalpies of Cyclic Ethers with Cyclohexane, Methylcyclohexane, or Chlorocyclohexane

Excess molar enthalpies for mixtures of tetrahydrofuran, tetrahydropyran, 2-methyltetrahydrofuran or 2,5-dimethyltetrahydrofuran with cyclohexane, methylcyclohexane, or chlorocyclohexane were determined at 25°C. The excess enthalpies are positive for the mixtures containing cyclohexane or methylcyclohexane, but negative for the mixtures containing chlorocyclohexane. The results were used with the Prigogine–Flory–Patterson theory to predict the corresponding excess molar volumes.     

二元有机液体混合物热容与过剩热容的测定

溶液的热容及过剩热容是热力学的重要函数，对其测定与研究具有理论与实际意义．首先，热容是化工传热计算中的基础数据，过剩热容则可检验溶液中分子间的相互作用，并可利用其计算混合物的热容．本文报告了用法国Setaram公司生产的MS-80型Calvet微量热仪对环己酮-芳烃（苯、甲     

Thermodynamics of liquid mixtures containing n-alkanes and strongly polar components: VE and C P E of mixtures with either pyridine or piperidine

Excess molar volumes V _E and excess molar heat capacities C _P ^/E at constant pressure have been obtained, as a function of mole fraction x₁, for several binary liquid mixtures belonging either to series I: pyridine+n-alkane (C_lH_2l+2), with l=7, 10, 14, 16, or series II: piperidine+n-alkane, with l=7, 8, 10, 12, 14. The instruments used were a vibrating-tube densimeter and a Picker flow microcalorimeter, respectively. V ^E of pyridine+n-heptane shows a S-shaped composition dependence with a small negative part in the region rich in pyridine (x₁>0.90). All the other systems show positive V ^E only. The excess volumes increase with increasing chain length l of the n-alkane. The excess molar heat capacities of the mixtures belonging to series II are all negative, except for a small positive part for piperidine+n-heptane in the region rich in piperidine (x₁>0.87). The C _P ^/E at the respective minima, C _P ^/E (x_1,min ), become more negative with increasing l, and the x_1,min values range from about 0.26 (l=7) to 0.39 (l=14). Most interestingly, mixtures of series I exhibit curves of C _P ^/E against x₁ with two minima and one maximum, the so-called W-shape curves.Dedicated to Professor A. Néckel on the occasion of his 65^th birthday. Communicated in part at the XVII^èmes Journées de Calorimétrie, d'Analyse Thermique et de Thermodynamique Chimique, Ferrara, Italy, 27–30 October, 1986.     

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.     

Solubility in Binary Solvent Systems: Comparison of Predictive Equations Derived from the NIBS Model

Abstract

Experimental solubilities are reported for pyrene in binary solvent mixtures containing benzene with n-hexane, cyclohexane, n-heptane, n-octane, cyclooctane and isooctane at 26°C. Results of these measurements, combined with published pyrene and biphenyl solubilities, are used to test predictive expressions derived from the Nearly Ideal Binary Solvent (NIBS) model. The most successful equation in terms of goodness of fit involved a surface fraction average of the excess Gibbs free energy relative to Raoult's law and predicted the experimental solubilities in 17 systems with an average deviation of 2.3% and a maximum deviation of 8.9%. Two expressions approximating weighting factors with molar volumes provided accurate predictions in many systems studied but failed in their ability to predict pyrene solubilities in solvent mixtures containing benzene.     

苯、甲苯与某些极性溶剂在293.15 K的过量体积

某些极性有机溶剂与烯烃、芳烃的特殊相互作用,是这些极性溶剂能够将烯烃、芳烃自烷烃中分离的基础。其分离的选择性决定于这种特殊相互作用。 L.J.Andrews认为腈类化合物、酮类化合物能与苯或苯的甲基衍生物生成电荷转移络合物,如苯与四氰基乙烯的络合物。R.F.Weimer和J.M.Prausnitz用紫外分光光度法测定过对-二甲苯与丙腈、丙酮、N-甲基吡咯烷酮等物的分子络合常数。我们也用分光光度法测定过某些芳烃与N-甲基吡咯烷酮的分子络合常数。