Thermodynamic properties of the mixture [x1,3-dioxane+(1-x) 1,4-dioxane] at the temperature 298.15 K

Excess enthalpies, excess heat capacities, excess volumes and sound velocities of the mixture of dioxane isomers, 1,3-dioxane and 1,4-dioxane, were measured. One of the isomers, 1,4-dioxane is considered as non-polar liquid and the other as polar liquid. Excess enthalpies are positive and small, less than 55 J mol^-1. Excess heat capacities are also very small and the curve is W-shaped, and the values are from 0.03 to -0.08 J mol^-1 K^-1. Excess volumes and excess isentropic compressibilities are small and positive, and less than 0.03 cm³ mol^-1 and 0.8 TPa^-1. This revised version was published online in August 2006 with corrections to the Cover Date.     

Molar heat capacities for (1-butanol + 1,4-butanediol, 2,3-butanediol, 1,2-butanediol, and 2-methyl-2,4-pentanediol) as function of temperature

The isobaric molar heat capacities for the binary mixtures (1-butanol + 1,4-butanediol) were determined in the temperature range from (293 to 353) K from measurements of isobaric specific heat capacity in a differential scanning calorimeter. The composition dependencies of the excess molar isobaric heat capacities obtained from the experimental results were fitted by the Redlich-Kister polynomials. Above T = 303.15 K, the excess isobaric molar heat capacities are negative over the whole composition range and absolute values increase with temperature. For temperatures (293.15 and 298.15) K, the excess values show S-shaped character. These excesses are however in general very small; at the temperature 298.15 K smaller than 0.1 J · K⁻¹ · mol⁻¹.Additionally, the isobaric molar heat capacities of 2,3-butanediol, 1,2-butanediol, and 2-methyl-2,4-pentanediol were determined over a similar temperature range. The experimental data for all diols are compared with available literature data and values estimated from group additivity.     

Excess enthalpies for mixtures of cyclohexanone with isomeric propanols and butanols at 298.15 K

Excess enthalpies (H ^E ) for mixtures of cyclohexanone with propan-1-ol. propan-2-ol, butan-1-ol, butan-2-ol and 2-methyl propan-1-ol at 298.15 K have been measured over the entire composition range. All mixed endothermically with the maximum values ofH ^E occurring at equimole fraction. Comments about the molecular interactions contributing to the excess enthalpies of a cyclic ketone + an alcohol are made on the basis of these results.     

Excess enthalpies and excess heat capacities of the binary mixtures of acetonitrile,dimethylformamide, and benzene at 298.15 K

Excess enthalpies and excess isobaric heat capacities of binary mixtures consisting of acetonitrile, dimethylformamide and benzene were measured at 298.15 K. Excess enthalpy of acetonitrile + benzene is positive and that of acetonitrile + dimethylformamide is negative. That of dimethylformamide + benzene is positive and nearly equals to zero as shown in the previous report [1]. Excess heat capacities of acetonitrile + benzene and benzene + dimethylformamide change sign from negative to positive with increase of benzene. That of acetonitrile + dimethylformamide is not simple. It is slightly positive near both ends of mole fraction and not so large negative in the middle of mole fraction. The curve tends to flatten in that region.

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Zusammenfassung An binären Gemischen aus Acetonitril, Dimethylformamid und Benzol wurden bei 298.15 K die Überschußenthalpien und die isobaren Überschußwärmekapazitäten gemessen. Die Überschußenthalpie von Acetonitril + Benzol ist positiv, die von Acetonitril + Dimethylformamid ist negativ. Die Überschußenthalpie ist bei Dimethylformamid positiv und wie bereits berichtet [1] annähernd Null. Die Überschußwärmekapazität von Acetonitril + Benzol und Benzol + Dimethylformamid wechselt bei Zunahme von Benzol das Vorzeichen von negativ zu positiv. Die von Acetonitril + Dimethylformamid ist nicht einfach. An beiden Enden der Molenbruchskaie ist sie leicht positiv und nicht allzu negativ in der Mitte der Molenbruchskale. Die Kurve flacht in dieser Region ab.

     

Heat capacities of binary cycloalkane mixtures at 298.15 K

Volumetric heat capacities of the six binary mixtures formed from cyclopentane, cyclohexane, cycloheptane and cyclooctane were determined at 298.15 K in a Picker flow microcalorimeter. Excess heat capacities obtained from the results are compred with the temperature variation of excess enthalpies from the literature.     

Mixtures formed of alkyl acetates with olive oil at 298.15 k

Enthalpies of mixing and heat capacities of the systems formed of alkyl acetates (ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate and isobutyl acetate) with olive oil were measured at 298.15 K. The mixing of acetates with the oil was strongly endothermic, and the highest measured enthalpies per mole of mixture were 2000 J mol^-1 for ethyl acetate at an acetate mole fraction of 0.6. The heat capacities of the mixtures were calculated too and values were decreasing as the mole fraction of acetate increases and varied from 296 to 3929 J K^-1 mol^-1. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermodynamic excess functions of methanol + piperidine at 298.15 K

Vapour pressures of methanol + piperidine at 298.15, 308.15, and 318.15 K were measured by a static method. Excess enthalpies and densities of the same mixtures at 298.15 K were also determined with an isothermal dilution calorimeter and a pyknometer. The excess functions were evaluated from these results; the values for mole fraction x = 0.5 at 298.15 K are: G^{E = ?834.1 Jmol?1}, H^{E = ?3159.1 Jmol?1}, TS^{E = ?2325.0 Jmol?1}, V^{E = ?1.26 cm3mol?1}.     

Excess heat capacities and excess volumes of binary liquid mixtures of chloroform with cyclic ethers at 298.15 K

Molar excess heat capacities at constant pressure, C^E_p, of binary liquid mixtures chloroform + oxolane, chloroform + 1,3-dioxolane, chloroform + oxane, and chloroform + 1,4-dioxane have been determined at 298.15 K from measurements of volumetric heat capacities in a Picker flow microcalorimeter. A precision of ±0.04 J K^?1 mole^? was achieved by using the stepwise procedure. Experimental molar excess heat capacities are compared with values derived from H^E results at different temperatures. Excess molar volumes, V^E, for the same systems at 298.15 K have been determined by measuring the density of the pure liquids and solutions with a high-precision digital flow densimeter.     

Excess enthalpies of ketone+methyl methylthiomethyl sulfoxide or +dimethyl sulfoxide at 298.15 k

Excess enthalpies of sixteen binary mixtures between one each of methyl methylthiomethyl sulfoxide (MMTSO) and dimethyl sulfoxide (DMSO) and one of ketone {CH₃CO(CH₂)_nCH₃, n=0 to 6 and CH₃COC₆H₅} have been determined at 298.15 K. All the mixtures showed positive excess enthalpies over the whole range of mole fractions. Excess enthalpies of ketone+MMTSO or DMSO increased with increasing the number of methylene radicals in the methyl alkyl ketone molecules. Excess enthalpies of MMTSO+ketone are smaller than those of DMSO+ketone for the same ketone mixtures. The limiting excess partial molar enthalpies of the ketone, H ₁ ^E,∞, in all the mixtures with MMTSO were smaller than those of DMSO. Linear relationships were obtained between limiting excess partial molar enthalpies and the number of methylene groups except 2-propanone.     

Excess thermodynamics properties of propyl propanoate+hexane+cyclohexane at 298.15 K

Summary In this paper we present excess molar volumes and excess molar enthalpies of binary and ternary mixtures containing propyl propanoate, hexane and cyclohexane as components at 298.15 K. Excess molar volumes were calculated from the density of the pure liquids and mixtures. The density was measured using an Anton Paar DMA 60/602 vibrating-tube densimeter. Excess molar enthalpies were obtained using a Calvet microcalorimeter     

Excess molar heat capacities of (<Emphasis Type="Italic">L</Emphasis>-glutamine aqueous solution+<Emphasis Type="Italic">D</Emphasis>-glutamine aqueous solution) at temperatures between 293.15 and 303.15 K

Summary Excess molar heat capacities of (L-glutamine aqueous solution+D-glutamine aqueous solution) were determined by using a differential scanning calorimeter at temperatures between 293.15 and 303.15 K. Excess molar heat capacities are all negative. Excess molar heat capacities decrease with increasing temperature.     

Excess properties and spectroscopic studies of binary system 1,4-butanediol + water at T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K

Density and dynamic viscosity data were measured over the whole concentration range for the binary system 1,4-butanediol (1) + water (2) at T = (293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K as a function of composition under atmospheric pressure. Based on density and dynamic viscosity data, excess molar density (ρ^E), dynamic viscosity deviation (Δν) and excess molar volume (V_m^E) were calculated. From the dynamic viscosity data, excess Gibbs energies (ΔG*^E), Gibbs free energy of activation of viscous flow (ΔG*), enthalpy of activation for viscous flow (ΔH*) and entropy of activation for viscous flow (ΔS*) were also calculated. The ρ^E, V_m^E, Δν and ΔG*^E values were correlated by a Redlich?Kister-type function to obtain the coefficients and to estimate the standard deviations between the experimental and calculated quantities. Based on FTIR and UV spectral results, the intermolecular interaction of 1,4-butanediol with H₂O was discussed.     

Excess enthalpies of cycloether + methyl methylthiomethyl sulfoxide or dimethyl sulfoxide at 298.15 K

Excess enthalpies of ten binary mixtures of each of methyl methylthiomethyl sulfoxide (MMTSO) and dimethyl sulfoxide (DMSO) with one of the cycloethers (oxane, 1,3- and 1,4-dioxanes, oxolane and 1,3-dioxolane) have been determined at 298.15 K. All the mixtures show positive excess enthalpies over the whole composition range. Excess enthalpies of the cycloether + MMTSO or DMSO decrease with increasing number of oxygen atoms in the cycloether molecules, except for oxolane + MMTSO. Excess enthalpies of MMTSO + cycloethers are smaller than those of DMSO + cycloethers for the same cycloether except for the 1,3-dioxolane mixtures.

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Zusammenfassung Bei 298.15 K wurden die Überschußenthalpien von zehn binären Gemischen aus jeweils Methylmethylthiomethylsulfoxid (MMTSO) bzw. Dimethylsulfoxid (DMSO) mit einem der cyclischen Ether (Oxan, 1,3- und 1,4-Dioxan, Oxolan und 1,3-Dioxolan) bestimmt. Alle Gemische zeigen im gesamten Konzentrationsbereich eine positive Überschußenthalpie. Die Überschußenthalpien von Cycloether + MMTSO oder DMSO sinken mit zunehmender Anzahl der Sauerstoffatome im cyclischen Ether, mit Ausnahme von Oxolan + MMTSO. Die Überschußenthalpien für MMTSO + Cycloether sind kleiner als die für DMSO + entsprechender Cycloether, eine Ausnahme bilden die Gemische mit 1,3-Dioxolan.

     

Enthalpies of mixing of <Emphasis Type="Italic">o</Emphasis>- and <Emphasis Type="Italic">m</Emphasis>-isomers at 298.15 K

Excess enthalpies (H ^E) of 17 binary mixtures of o- and m-isomers of dichlorobenzene, difluorobenzene, methoxymethylbenzene, dimethylbenzene, dimethoxybenzene, aminofluorobenzene, fluoronitrobenzene, diethylbenzene, chlorofluorobenzene, fluoroiodobenzene, bromofluorobenzene, chloromethylbenzene, fluoromethylbenzene, bromomethylbenzene, iodomethylbenzene, fluoromethoxybenzene, dibromobenzene at 298.15 K were measured. All excess enthalpies measured were very small, and those of o-+m-isomers of aminofluorobenzene, dibromobenzene and iodomethylbenzene were negative but 14 other binary mixtures of isomers were positive over the whole range of mole fractions. H ^E of o-+m-isomers of dimethoxybenzene showed the largest enthalpic instability and those of aminofluorobenzene showed the largest enthalpic stability. There was a correlation between dipole–dipole interaction, dipole–induced dipole interaction or entropies of vaporization and excess partial molar enthalpies at infinite dilution.     

Excess enthalpies for mixtures of acrylonitrile and an aromatic hydrocarbon at T = 298.15 K and p = 101325 Pa

Excess molar enthalpies for (acrylonitrile  +  benzene, or methylbenzene, or 1,2-dimethylbenzene, or 1,3-dimethylbenzene, or 1,4-dimethylbenzene, or 1,3,5-trimethylbenzene, or ethylbenzene) atT =  298.15 K and p =  101325 Pa are presented. The excess molar enthalpy range from 531J · mol ^− 1at x =  0.5 for 1,3,5-trimethylbenzene to 210J · mol ^− 1at x =  0.5 for toluene. The Redlich–Kister equation, the NRTL and UNIQUAC models were used to correlate the data.     

Deuterium Isotope Effect on Excess Enthalpies of Methanol or Ethanol and Their Deuterium Derivatives at 298.15 K

Excess enthalpies of six binary mixtures of CH₃ OD+CH₃ OH, CH₃ OD+CD₃ OD, CD₃ OD+CH₃ OH, C₂ D₅ OD+C₂ H₅ OH, C₂ D₅ OD+C₂ H₅ OD, C₂ H₅ OD+C₂ H₅ OH have been determined over the whole range of mole fractions at 298.15 K in order to know the isotopic effect on hydrogen-bonding accurately, although there are many reports on the differences in the strength of hydrogen-bonding between OH and OD. All excess enthalpies measured are very small and endothermic. The mixtures of CH₃ OD+ CH₃ OH, and C₂ D₅ OD+C₂ H₅ OH showed the largest excess enthalpies among each methanol and ethanol mixtures. The difference of intermolecular interaction between OH and OD in methanol and ethanol was almost same value of (1.82±0.04) J mol^-1 Excess enthalpies of 1,4-dimethylbenzene+1,3-dimethylbenzene and 1,4-dimethylbenzene+1,2-methylbenzene were measured by three different principle calorimeters at 298.15 K in order to know the precision of calorimetry for a small enthalpy change. This revised version was published online in July 2006 with corrections to the Cover Date.     

Excess enthalpies of water+1,4-dioxane at 278.15, 298.15, 318.15 and 338.15 K

The excess molar enthalpies of (1–x)water+x1,4-dioxane have been measured at four different temperatures. All the mixtures showed negative enthalpies in the range of low mole fraction but positive ones in the range of high mole fraction of 1,4-dioxane. Excess enthalpies were increased with increasing temperature except those of at 278.15 K. Partial molar enthalpies have maximum around x=0.13 and minimum around x=0.75. Three different behaviors for the concentration dependence of partial molar enthalpies were observed for all temperature. Theoretical calculations of molecular interactions of three characteristic concentrations were carried out using the molecular orbital method.     

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 volumes and excess heat capacities of nitromethane+(1-propanol or 2-propanol)

Densities and heat capacities of binary mixtures containing nitromethane+(1-propanol or 2-propanol) were determined at the temperatures (288.15, 293.15, 298.15, and 308.15) K and atmospheric pressure, over the whole composition range. Excess molar volumes and excess molar isobaric heat capacities were calculated from the results thus obtained. The effect of specific interactions on the excess properties, and the dependence on the position of the OH group in the alkanol, are analysed.     

The determination of activity coefficients at infinite dilution using g.l.c. for hydrocarbons in furfural at T=278.15 K and T=298.15 K

The activity coefficients at infinite dilution for some alkanes, cycloalkanes, alkenes, alkynes and benzene in furfural have been determined by g.l.c. at T=278.15 K and T=298.15 K. The volatility of the solvent furfural, although low, was taken into account. The method used is an alternative to the pre-saturation method. The results have been used to predict the potential for furfural as a solvent in separating aromatic compounds from aliphatic compounds and other hydrocarbons using extractive distillation. The excess enthalpies of mixing at infinite dilution have also been calculated.