Excess enthalpies of binary and ternary mixtures of acetonitrile with methanol,ethanol and benzene

Excess molar enthalpies are measured for the binary mixtures methanol—acetonitrile and ethanol—acetonitrile at 25 and 35°C and for the ternary mixtures methanol—acetonitrile—benzene and ethanol—acetonitrile—benzene at 25°C using an isothermal dilution calorimeter. The binary results are well reproduced with an association model which contains four equilibrium constants for the association of alcohol, two equilibrium constants for that of acetonitrile, and two solvation equilibrium constants between alcohol and acetonitrile molecules. The ternary results are compared with those calculated from the model with binary parameters.     

Adiabatic compressibility of critical binary mixtures of nitroethane/isooctane and nitroethane/3-methylpentane

The adiabatic compressibility β_S of nitroethane/isooctane is measured from 18 to 900 Hz at reduced temperatures ? ranging from 5 × 10^-5 to 5 × 10^-2. The zero-frequency compressibility extrapolated from the data is related with the specific heat at constant pressure c_p through the theory of Ferrell and Bhattacharjee (FB). The coupling constant g is evaluated from this relation as 0.38, which agrees with that from the thermodynamic definition of g. β_S at 900 Hz is observed for nitroethane/3-methylpentane at ? 5 × 10^-5-6 × 10^-2. A linear plot of the critical part of β_S against 1n? gives g = 0.34, which agrees with g from the thermodynamic definition and also with that from ultrasonic absorption. Numerical values of the critical and background components of β_S, the isothermal compressibility β_T, c_p, the specific heat at constant volume c_v, and the thermal expansion coefficient α_p are calculated for the two mixtures. The expression of β_S from Anisimov's theory is found to be consistent with that from the FB theory.     

Vapor-liquid equilibria in binary mixtures formed from hexamethyldisiloxane,toluene and ethanol

Vapor-liquid equilibria have been measured in the binary systems hexamethyldisiloxane-toluene, hexamethyldisiloxane-ethanol and toluene-ethanol between 333.15 and 358.15 K and the results have been correlated using the Wilson equation. All three binary systems exhibit azeotropic behavior in the temperature range studied.     

Immersion enthalpy of benzene/cyclohexane and toluene/cyclohexane binary mixtures into modified activated carbons

Journal of Thermal Analysis and Calorimetry - The interaction between binary mixtures of benzene/cyclohexane and toluene/cyclohexane into three activated carbons with different physical and...     

Electrochemical bromination of benzene,toluene and xylene in acetonitrile

A method for the preparation of bromo derivative compounds of aromatics is proposed and the electrodic process involved in the bromination on the third wave of the system Br^?/aromatic substrate in acetonitrile is discussed.     

Excess enthalpies and complex formation of acetonitrile with acetone,chloroform, and benzene

Excess enthalpies of binary systems of acetonitrile—acetone, chloroform—acetone and chloroform—benzene, and ternary systems of acetonitrile—chloroform—acetone and acetonitrile—chloroform—benzene are reported at 25°C. The results are analyzed with thermodynamic association theory for complex ternary liquid mixtures. The theory involves two types of self-association of acetonitrile, formation and binary complexes for component pairs of a ternary system, and a nonspecific interaction term expressed by the NRTL equation between various chemical species.     

Phase behaviour of binary n-alkanenitrile and n-alkane,and nitromethane and alkane mixtures

Upper critical solution temperatures of nitromethane and alkanes, and alkanenitriles and alkanes have been used to obtain a parameter, ψ, characterising the interaction between the pairs of unlike molecules in the mixture. Values of ψ have been calculated using a “hard sphere and attractive force” equation of state together with the van der Waal's one fluid model.Values of ψ obtained for the ethanenitrile and alkane mixtures have been compared with those obtained from an analysis of gas—liquid critical temperatures. There is a discrepancy of several percent between the values calculated from the two properties.     

Dielectric properties of mixtures of acetylene tetrachloride with toluene and acetone

Relative permittivities are reported for binary liquid mixtures of acetylene tetrachloride (ATC) with toluene and acetone at 35°C. Measurements of refractive indices have also been made for the mixtures. The values of the quantity , the deviations of the relative permittivities of these mixtures from ideality, have been calculated. The negative values of obtained for ATC+ toluene mixtures may be explained as being due to a decrease in the degree of alignment of the molecular dipoles with changing composition of the mixture, whereas the positive values of obtained for ATC+acetone mixtures are attributed to the formation of molecular complex between acetone and CHCl₂CHCl₂. The values of the Kirkwood correlation parameter g for both sets of mixtures have been calculated using the relative permittivity data.     

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.

     

Electro-kinetic transport of acetone,water and their binary mixtures

Summary Electroosmosis of acetone, water and their binary mixtures through thorium oxide (ThO₂) plug membrane has been studied and the data analysed using non-equilibrium thermodynamics. The phenomenological coefficients,L ₁₁ andL ₁₂ have been found to vary nonlinearly with composition. Excess phenomenological coefficients have therefore been evaluated and the results explained in terms of the membrane permeant and permeant-permeant interactions. The results on the measurement of electrophoretic velocity of ThO₂ particles dispersed in acetone-water mixtures also lead to the conclusion that the components of the mixture interact appreciably.

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Zusammenfassung Die Elektroosmose von Aceton, Wasser and deren binären Gemische durch eine ThO₂-Pflock-Membran wurde untersucht; die Daten wurden mit Hilfe der Nichtgleich-gewichts-Thermodynamik analysiert. Die phänomenologischen KoeffizientenL ₁₁ undL ₁₂ ändern sich hiernach nichtlinear mit der Zusammensetzung. Es wurden daher Exzess-L ₁₁-und -L ₁₂-Werte berechnet; die Ergebnisse wurden auf Grund der Membran-Permeant- und Permeant-Permeant-Wechselwirkungen diskutiert. Aus der Messung der elektrophoretischen Geschwindigkeit von ThO₂-Teilchen, die in Aceton-Wasser-Gemischen dispergiert sind, folgt, daß eine merkliche Wechselwirkung zwischen den Komponenten der Mischung vorliegt.

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Excess properties of binary mixtures hexane,heptane, octane and nonane with benzene,toluene and ethylbenzene at T = 283.15 and 298.15 K

Densities, speeds of sound and the refractive indices of binary systems containing alkanes (hexane, heptane, octane and nonane) with aromatic compounds (benzene, toluene and ethylbenzene) at T = 283.15 and 298.15 K under atmospheric pressure were determined over the whole composition range. From the experimental results, the derived and excess properties (excess molar volumes, isentropic compressibility, excess molar isentropic compressibility and refractive index deviations) at T = 283.15 and 298.15 K were calculated and satisfactorily fitted to the Redlich–Kister equation.     

Study of the isotropic to smectic-A phase transition in liquid crystal and acetone binary mixtures

The first-order transition from the isotropic (I) to smectic-A (Sm?A) phase in the liquid crystal 4-cyano-4(')-decylbiphenyl (10CB) doped with the polar solvent acetone (ace) has been studied as a function of solvent concentration by high-resolution ac-calorimetry. Heating and cooling scans were performed for miscible 10CB+ace samples having acetone mole fractions from x(ace)=0.05 (1 wt?%) to 0.36 (10%) over a wide temperature range from 310 to 327 K. Two distinct first-order phase transition features are observed in the mixture whereas there is only one transition (I-Sm?A) in the pure 10CB for that particular temperature range. Both calorimetric features reproduce on repeated heating and cooling scans and evolve with increasing x(ace) with the high-temperature feature relatively stable in temperature but reduced in size while the low-temperature feature shifts dramatically to lower temperature and exhibits increased dispersion. The coexistence region increases for the low-temperature feature but remains fairly constant for the high-temperature feature as a function of x(ace). Polarizing optical microscopy supports the identification of a smectic phase below the high-temperature heat capacity signature indicating that the low-temperature feature represents an injected smectic-smectic phase transition. These effects may be the consequence of screening the intermolecular potential of the liquid crystals by the solvent that stabilizes a weak smectic phase intermediate of the isotropic and pure smectic-A.     

The interphase between mercury and acetone+ nitromethane mixtures with KPF6 as a supporting electrolyte

Differential capacity and interfacial tension measurements were carried out on mercury for acetone+nitromethane mixtures with KPF₆ as a supporting electrolyte. On the basis of Gibbs adsorption equation and Guggenheim's model of the surface phase the composition of the surface layer was estimated for different acetone contents and different charges on the mercury electrode. The results obtained indicate that the positive acetone adsorption is marked at negative charges with maximum at σ_m=?0.07 C m^?2, but is practically non-existent at zero and positive charges.     

Prediction of viscosities and COSMO-RS analyses in binary mixtures of N,N-dimethylformamide with acetone

Experimental viscosities, η, for pure N,N-dimethylformamide (DMF) and acetone (ACT) and their binary mixtures are measured over the whole composition range as a function of temperature between 298.15 and 313.15 K. The deviations in viscosity, ?η, Gibbs free energy of activation ?G, entropies ?S*, enthalpies ?H of activation of viscous flow have been calculated. The determination of excess molar volumes, Vη^E, was calculated from the experimental viscosities for the binary mixtures. The conductor-like screening model is applied to interpret the intermolecular forces. The σ-profile is computed for the N,N-DMF and ACT with conductor-like screening model for real solvents. The experimental results were found to be in good agreement with the theoretical predictions. Moreover, viscosity data were calculated from the theoretical equations of Grunberg and Nissan, Hind et al. and Wilke for the entire systems. All results obtained were averaged experimentally and theoretically in terms of average deviations.     

Studies on interactions of ions with nitromethane and acetonitrile using CNDO/force method

CNDO/force calculations on the complexes of nitromethane and acetonitrile with H⁺, Li⁺, F⁻ and Cl⁻ have been carried out to determine their geometrical parameters and stretching force constants. The results are discussed in terms of specific interactions between the ions and the molecules.     

Michael monoadditions of nitromethane or nitroethane with electrophilic gem-disubstituted alkenes over alumina under microwave irradiation

Nitromethane 1a or nitroethane 1b react with electrophilic alkenes 2a-i RCHC(CN)(Y) with Y=CO₂R′, CN, CONH₂ adsorbed on alumina to give selectively at room temperature or under focused microwave irradiation new Michael monoadducts 5 (two diastereoisomers) or 6 (four diastereoisomers) after a few minutes. It is possible to obtain only two diastereoisomers of 6 by reaction of the corresponding nitroalkene and methylcyanoacetate in the presence of catalytic amounts of piperidine. Mechanisms are proposed. Some examples of addition of nitroalkanes with electron-deficient alkynes in dry media coupled with microwave irradiation conditions are also described.     

Interfacial tensions of binary mixtures of ethanol with octane,decane, dodecane,and tetradecane

This contribution is devoted to the experimental characterization of interfacial tensions of a representative group of binary mixtures pertaining to the (ethanol + linear hydrocarbon) series (i.e. octane, decane, dodecane, and tetradecane). Experimental measurements were isothermically performed using a maximum differential bubble pressure technique, which was applied over the whole mole fraction range and over the temperature range 298.15 K < T/K < 318.15 K.Experimental results show that the interfacial tensions of (ethanol + octane or decane) negatively deviate from the linear behavior and that sharp minimum points on concentration, or aneotropes, are observed for each isotherm. The interfacial tensions of (ethanol + dodecane or tetradecane), in turn, are characterized by combined deviations from the linear behavior, and inflecting behavior observed on concentration for each isotherm. The experimental evidence also shows that these latter mixtures are close to exhibit aneotropy.For the case of (ethanol + octane or decane) mixtures, aneotropy was clearly induced by the similarity of the interfacial tension values of the constituents. The inflecting behavior of the interfacial tensions of (ethanol + dodecane or tetradecane), in turn, was observed in the vicinity of the coordinates of the critical point of these mixtures, thus pointing to the fact that the quasi-aneotropic singularity that affects these mixtures was provoked by the proximity of an immiscibility gap of the liquid phase.Finally, the experimental data of interfacial tensions were smoothed with the Scott–Myers expansion, from which it is possible to conclude that the observed aneotropic concentrations weakly depend on temperature for all the analyzed mixtures.