Volumetric and refractive properties of binary mixtures containing 1,3-dioxolane and isomeric chlorobutanes

The relation between refractive index deviations and excess volumes for binary mixtures formed by a cyclic ether and a haloalkane has been tested using several methods: refractive index mixing rules and equations of state. Refractive index deviations, excess volumes and molar refractions have been calculated from experimental data of refractive indices and densities at two temperatures 298.15 and 313.15 K. Results obtained have been discussed in terms of intermolecular interactions. Refractive indices were compared with those predicted by several mixing rules. Excess volumes have also been correlated using several cubic equations of state and finally a relation between parameter b from equations of state and molar refraction has been provided.     

Dielectric properties of ethyleneglycol-1,4-dioxane mixtures using TDR method

Complex permittivity has been determined for mixtures of ethyleneglycol-1,4-dioxane (EG-DX) with various concentrations in the frequency range from 100 MHz to 30 GHz at 25 degrees C by time domain reflectometry (TDR). A primary process with an asymmetric shape and a Debye-type small-amplitude high-frequency process are observed for each mixture. The deviation of the relaxation time for the primary process from that of the ideal mixture shows a maximum value at a mole fraction of 1,4-dioxane, xDX approximately =0.8. The static permittivity for the mixtures can be explained using the Luzar model by assuming the formation of two types of hydrogen-bonded dimers, one between EG-EG (pair 1) and the other between EG-DX (pair 2). The number of these pairs is also estimated as a function of concentration. These results of the relaxation time and static permittivity are interpreted on the basis of a model of two kinds of cooperative domains coexisting in the mixtures.     

Thermodynamic properties of binary mixtures containing hydrofluoroether

Excess molar enthalpy and excess molar volume at T =  298.15 K are reported for binary mixtures of (nonafluorobutylmethylether  +  butylmethylether, or nonane, or heptane, or pentane, or 1-propanol, or 2-propoxyethanol). Excess molar enthalpies of the mixture of (nonafluorobutylmethylether  +  1-pentanol) also are reported at T =  298.15 K. The results of excess molar enthalpy are endothermic and the results of excess molar volume are positive in the whole concentration for all the mixtures. The phase separation is found in the range of 0.15  < x <  0.92 for the 1-pentanol system. The results are explained by means of the destruction of the dipolar interactions and hydrogen bonds in the component liquids, the difference of the dispersion interaction, and the formation of the intermolecular hydrogen bonds between unlike molecules.     

Volumetric properties,viscosities and refractive indices of binary liquid mixtures of tetrafluoroborate-based ionic liquids with methanol at several temperatures

Densities, speeds of sound, viscosities and refractive indices of two binary systems 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF₄] + methanol and 1-ethyl-3-methylimidazolium tetrafluoroborate [emim][BF₄] + methanol, as well as of all pure components, have been measured covering the whole range of compositions at T = (278.15 to 318.15) K and p = 101 kPa. From this data, excess molar volumes, excess isentropic compressibilities, viscosity deviations and refractive index deviations were calculated and fitted to extended versions of the Redlich–Kister equation. Estimated coefficients of these equations taking into account the dependence on composition and temperature simultaneously were also presented.     

Thermophysical study of 1,4-dioxane with cycloalkane mixtures

Densities, refractive indices, and surface tension for the binary mixtures 1,4-dioxane with cyclopentane or cylohexane have been determined at ambient pressure and at T = (283.15, 298.15, and 313.15) K. Excess volumes and refractive index and surface tension deviations have been calculated from the experimental data. Several relations between the thermophysical properties studied here have been tested using our experimental results.     

Thermodynamic properties of binary mixtures containing 1-alkanols

Densities (ρ) of pure liquids and their mixtures have been measured at 303.15 and 313.15 K and atmospheric pressure over the entire composition range for the binary mixtures of benzylalcohol with 1-propanol, 1-butanol, 1-pentanol, and 1-hexanol by using Rudolph Research Analytical digital densitometer (DDM-2911 model). Further, the ultrasonic sound velocities for the above said mixtures were also measured at 303.15 and 313.15 K. The measured density data were used to compute excess molar volumes (V ^E) and these were compared with the values obtained by Hwang equation. Isentropic compressibility (κ _S) and excess isentropic compressibilities (κ _S ^E ) were evaluated from experimental sound velocity and density data. Moreover, the experimental sound velocities were analyzed in terms of theoretic models namely, collision factor theory and free length theory. The experimental results were discussed in terms of intermolecular interactions between component molecules.     

Volumetric and acoustic properties of the ternary system (1-butanol+1,4-dioxane+cyclohexane)

Densities and speeds of sound for the ternary system 1-butanol+1,4-dioxane+cyclohexane have been measured at the temperatures of 298.15 and 313.15 K. Excess molar volumes and excess isentropic compressibilities have been calculated from experimental data and fitted by the Redlich-Kister equation for ternary mixtures. The ERAS model has been used to calculate excess molar volumes of the ternary mixture from parameters obtained from the constituent binary mixtures.     

Hydrogen bonds in 1,4-dioxane/ammonia binary clusters

With synchrotron radiation, we have studied the photoionization and dissociation of 1,4-dioxane/ammonia clusters in a supersonic expansion. The observed major product ions are the 1,4-dioxane cation M(+) and protonated cluster ions M(NH(3))(n)H(+) (where M=1,4-dioxane), and the intensities of the unprotonated cluster ions M(NH(3))(n) (+) are much lower. Fully optimized geometries and energies of the neutral cluster M(NH(3))(2) and related cluster ions have been obtained using the ab initio molecular orbital method and density functional theory. The potential energy surface of the excited state of M(NH(3))(2) (+) was also calculated. With these results, the mechanisms of different photoionization-dissociation channels have been suggested. The most probable channel is electron ejection from the highest occupied molecular orbital, followed by the dissociation into M(+) and (NH(3))(2). For another main channel, after removing an electron from the second highest occupied molecular orbital, the intracluster proton transfer process takes place to form the stable unprotonated cluster ion M(NH(3))H(+)-NH(2), which usually leads to the dissociated protonated cluster ion M(NH(3))H(+) and a radical NH(2).     

Dielectric properties of binary mixtures of three butanediols with 1,4-dioxane and 2-ethyl-1-hexanol at T = 298.2 K

Experimental results of dielectric investigations for solutions of the three butanediols {2,3-butanediol (2,3BD), 1,3-butanediol (1,3BD), and 1,4-butanediol (1,4BD)}, in 1,4-dioxane (1,4DX) are reported for various mole fractions at T = 298.2 K. Values of relative permittivity were measured at 100 kHz. The molecular dipole moments were determined using Guggenheim method. The variations of effective dipole moment and correlation factor, g, with mole fraction in these materials were investigated using Kirkwood–Frohlich equation. Dielectric measurements were also carried out on binary polar mixtures of the butanediols with 2-ethyl-1-hexanol (2EH) for various concentrations at T = 298.2 K. The Kirkwood correlation factor, the Bruggeman factor, and the excess permittivity were determined.     

Volumetric properties of binary mixtures of alcoxyethanols with tert-butyl ethyl ether at various temperatures

Densities at 293.15, 298.15, 303.15, 308.15 and 313.15 K of the binary liquid mixtures made of tert-butyl ethyl ether with either 2-ethoxyethanol, or 2-(2-ethoxy)ethoxyethanol, or 2-[2-(2-ethoxy)ethoxy]ethoxyethanol have been measured over the whole mixture compositions. These data have been used to compute the excess molar volumes (V^E). The excess molar volumes always are negative over the entire range of composition for all the binary mixtures investigated. The changes of V^E with variations of the composition and the chain-length of the alkyl groups in the alkoxyethanol molecules are discussed in terms of possible intermolecular interactions.     

Solvent effect on the acidity constants of lignin-related phenols in water-acetone and water-1,4-dioxane binary mixtures within the Kamlet-Taft formalism

Multiparameter regression analysis combined with the principle of liner solvation energies relationship was applied to assess the solvent effect on the acidity of the lignin-related phenols in water-dioxane and water-acetone systems. The coefficients a, b, and s of the Kamlet-Taft equation were calculated taking into account the contributions of different types of solute-solvent interactions to the protolytic properties of the phenols of the guaiacol series.     

Orientational order and refractive indices in binary nematic mixtures

Mean field theory is used to calculate the temperature-composition phase diagram and component order parameters of binary nematic mixtures. Experimental values for the mixture order parameter of a binary nematic mixture close to the nematic/isotropic transition have been obtained from refractive index measurements. The experimental results qualitatively confirm the predictions of the theory.     

Thermodynamics of binary mixtures containing alkynes

Molar excess enthalpiesH ^E of 1-hexyne +n-heptane, +n-decane, +cyclohexane, and +benzene, and of 3-hexyne +n-heptane, +n-decane, +cyclohexane, and +benzene, at 298.15 K and atmospheric pressure were measured with a Picker type flow microcalorimeter. Generally, the 1-hexyne systems are more endothermic than the corresponding 3-hexyne systems, the increment ofH _mas ^E being of the order of 170 to 260 J/mol, which is clearly too large to be accounted for by orientational contributions toH ^E due to the permanent dipole moment of 1-hexyne. It is suggested that other contributions, for example contributions resulting from different conformational behavior of the hexynes, have to be considered.With 2 FiguresDidicated to Prof.H. Nowotny on the occasion of his 65th birthday. Communicated in part at the 2. Ulmer Kalorimetrietage, March 24–25, 1977, Ulm, Germany.     

Binary mixtures of cyclohexanone, 2-butanone, 1,4-dioxane and 1,2-dimethoxyethane

Densities and sound velocities of binary mixtures of cyclohexanone, 2-butanone, 1,4-dioxane and 1,2-dimethoxyethane were measured at 298.15 K and also the densities at 303.15 K. Excess volumes were determined from densities. Isentropic compressibilities were determined from densities and sound velocities, and excess thermal expansion factors were determined from excess volumes of two temperatures. Excess isothermal compressibilities and excess isochoric heat capacities were then estimated using excess isobaric heat capacities previously reported. Excess volumes and excess isentropic and isothermal compressibilities were negative except for cyclohexanone+1,4-dioxane system. This revised version was published online in August 2006 with corrections to the Cover Date.     

Excess molar volumes and viscosities of binary mixtures of 1,2-diethoxyethane with chloroalkanes at 298.15 K

Excess molar volumes (V _m ^E ) and viscosities (η) of the binary mixtures of 1,2-diethoxyethane with di-, tri- and tetrachloromethane have been measured at 298-15 K and atmospheric pressure over the entire mole fraction range. The deviations in viscosities (δlnη) and excess energies of activation (δG*^E) for viscous flow have been calculated from the experimental data. The Prigogine-Flory-Patterson (PFP) model has been used to calculateV _m ^E , and the results have been compared with experimental data. The Bloomfield and Dewan model has been used to calculate viscosity coefficients and these have also been compared with experimental data for the three mixtures. The results have been discussed in terms of dipole-dipole interactions between 1,2-diethoxyethane and chloroalkanes and their magnitudes decreasing with the dipole character of the molecules. A short comparative study with results for mixtures with polyethers and chloroalkanes is also described.