Liquid–Liquid Equilibria of Linalool + Ethanol + Water, Water + Ethanol + Limonene, and Limonene + Linalool + Water Systems

The present work was undertaken to determine liquid–liquid equilibria for ternary systems involved in the citrus essential oil terpeneless using dilute alcohol. Tie-line data have been determined for the linalool + ethanol + water, water + ethanol + limonene, and limonene + linalool + water ternary systems at 298.15 K. The experimental data were satisfactorily correlated using the UNIQUAC and NRTL equations, and the obtained binary interaction parameters are reported. The UNIFAC group-contribution method did not allow adequate predictions of liquid–liquid equilibria involved in this study.     

Gas—liquid equilibrium in hydrogen + tetralin + diphenylmethane and hydrogen + tetralin + m-xylene

Vapor—liquid equilibrium data in two ternary mixture systems, hydrogen + tetralin + diphenylmethane and hydrogen + tetralin + m-xylene, were determined in a flow apparatus at pressures 20–250 atm¹ for both systems, and temperatures 190–430°C for the first system and 190–310°C for the second. Mixed solvents approximately equi-molal in the organic compounds were studied. Henry constants of hydrogen in the mixed solvents were evaluated from the data. The results show that the solubility of hydrogen in these mixed hydrocarbon solvents can be completely predicted from solubilities in the pure component liquids.     

A photoionization study of the charge transfer reactions: Xe+ + O2 → O+2 + Xe and O+2 + Xe → Xe+ + O2

Photoionization mass spectrometer techniques have been employed to study the charge transfer reactions: Xe⁺ + O₂ → O⁺₂ + Xe and O⁺₂ + Xe → Xe⁺ + O₂. The results show the reaction of Xe⁺(²P_{$\text{3}\text{2}$}) ions with O₂ molecules is much more efficient than the reaction of Xe⁺(²P_{$\text{1}\text{2}$}) ions with O₂ molecules. The charge transfer reaction of O⁺₂ ions with Xe atoms was detected for O⁺₂ ions in the a ⁴Π_u state.     

Kinetics of the reactions Br + NO2 + M and I + NO2+ M

The reactions Br + NO₂ + M → BrNO₂ + M (1) and I + NO₂ + M → INO₂ + M (2) have been studied at low pressure (0.6-2.2 torr) at room temperature and with helium as the third body by the discharge-flow technique with EPR and mass spectrometric analysis of the species. The following third order rate constants were found k₁₍₀₎ = (3.7 ± 0.7) × 10^?31 and k₂₍₀₎ = (0.95 ± 0.35) × 10^?31 (units are cm⁶ molecule^?2 s^?1). The secondary reactions X + XNO₂ → X₂ + NO₂ (X = Br, I) have been studied by mass spectrometry and their rate constants have been estimated from product analysis and computer modeling.     

Ni+Pd+Ga and Ni+Pd+in liquid alloys: Enthalpies of formation

In order to fill the evident gap in the thermodynamic data of nickel-palladium-gallium and nickel-palladium-indium ternary alloys, the enthalpies of formation of these systems in the liquid state have been determined. This was achieved by means of a very high temperature calorimeter (T<1800 K), using the direct drop method, and based on analogous measurements of the respective binary alloys previously published. Complete automation of the calorimeter led to a good precision even at the highest temperatures. The enthalpies of formation of the ternary liquid alloys were measured between 1400 and 1600 K on the whole composition range. As in the limiting binary systems, enthalpies of formation are negative and non temperature dependent at any composition.

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Zusammenfassung Um die Lücke hinsichtlich thermodynamischer Daten von Nickel-Palladium-Gallium und Nickel-Palladium-Indium Legierungen zu füllen, wurden die Bildungsenthalpien dieser ternÄren Systeme im flüssigen Zustand bestimmt. Dies erfolgte mittels eines Kalorimeters für sehr hohe Temperaturen (T<1800 K), unter Verwendung der direkten Einwurfmethode auf der Basis früher veröffentlichter Messungen an den entsprechenden binÄren Systemen. Die Bildungsenthalpien der flüssigen ternÄren Legierungen wurden zwischen 1400 und 1600 K über den gesamten Zusammensetzungsbereich bestimmt. VollstÄndige Automation des Kalorimeters bewirkte hohe PrÄzision selbst bei den höchsten Temperaturen. Wie in den begrenzenden binÄren Systemen sind die Bildungsenthalpien negativ und bei allen Zusammensetzungen nicht temperaturabhÄngig.

     

Thermochemistry of HCOS+ and HCS2+

Heats of formation for HCOS⁺ and HCS₂⁺, obtained from high-quality ab initio calculations, have been used to determine the thermochemistry of several reactions which may form these ions in interstellar clouds or mass spectrometer experiments. Radiative association of HCO⁺ or HCS⁺ with either O or S may be important in interstellar clouds, whereas proton transfer from H₃⁺ or HCO⁺ to CS₂ or COS may be a means of synthesizing these ions by mass spectrometry. In the latter case, the relevant heats of formation are: HCS₂⁺(¹A₁) 1042 kJ mol^?1 and HCOS⁺ (¹A′) 996 kJ mol^?1.     

Liquid-liquid equilibria of (cyclohexane + acetonitrile + methylcyclohexane + toluene) and of {(acetonitrile + methylcyclohexane) + benzene or + toluene or + cyclohexane or + chlorobenzene} at 298.15 K

Tie-line results at 298.15 K and atmospheric pressure are reported for (cyclohexane + acetonitrile + methylcyclohexane + toluene) and for {(acetonitrile + methylcyclohexane) + benzene or + toluene or + cyclohexane or + chlorobenzene). The extended UNIQUAC and UNIQUAC equations are used to correlate binary vapour-liquid equilibria and mutual solubilities for 10 mixtures constituting the ternary mixtures and to predict the ternary and quaternary liquid-liquid equilibria by use of only binary parameters.     

Excess molar enthalpies of triethylamine + ethylbenzene, + n-propylbenzene, + n-butylbenzene, + isopropylbenzene,and + isobutylbenzene at 303.15 K

Excess molar enthalpies H_m^E of triethylamine + ethylbenzene, + n-propylbenzene, + n-butylbenzene, + isopropylbenzene, and + isobutylbenzene were measured over the entire composition range at 303.15 K with an LKB flow microcalorimeter. H_m^E values are positive and decrease with increasing chain length of the alkylbenzene.     

Density and Viscosity of Methanol + Trichloroethylene,n-Propanol + Trichloroethylene and n-Butanol + Trichloroethylene Mixtures

Abstract

Density and Viscosity measurements on the binary mixtures of methanol + trichloro-ethylene, n-propanol + trichloroethylene, and n-butanol + trichloroethylene binary mixtures at 303.15, 313.15 and 323.15K are reported. The representation of the data by simple mixing rules is also studied.     

Deadwood in configuration spaces. II. Singles + doubles and singles + doubles + triples + quadruples spaces

The effect of truncating singles + doubles configuration interaction (CISD) and singles + doubles + triples + quadruples (CISDTQ) spaces on the energies of the systems Ne, H₂O, CO and C₂ is investigated through the use of a previously described, general, selected CI program. CI expansions generated by Hartree–Fock orbitals as well as by natural orbitals are examined and the latter typically exhibit faster convergence as regards the energy. For the CISD wavefunctions of Ne, H₂O, CO and C₂, chemical accuracy is reached by using, respectively, 34, 47, 53 and 55% of the full sets. For the triples + quadruples parts of the wavefunctions on the other hand, chemical accuracy is already reached by using only 1, 4, 6 and 9% of the respective full sets. Received: 14 August 2001 / Accepted: 6 December 2001 / Published online: 8 April 2002     

The excess volumes of decahydronaphthalene + cyclopentane, + cyclohexane, + cycloheptane and + cyclooctane at two temperatures

The excess volumes of decahydronaphthalene (decalin) + cyclopentane, + cyclohexane, + cycloheptane and + cyclooctane have been measured over the whole composition range at two temperatures. These measurements show many similarities to the V_m^E results of bicyclohexyl + a cycloalkane and 1,2,3,4-tetrahydronaphthalene (tetralin) + a cycloalkane.     

Liquid-liquid equilibria for the acetonitrile + methanol + saturated hydrocarbon and acetonitrile + 1-butanol + saturated hydrocarbon systems

Tie-line results at 25°C and atmospheric pressure are presented for {(acetonitrile + methanol) + cyclohexane, or + n-hexane, or + n-heptane or + n-octane} and for {(acetonitrile + 1-butanol) + cyclohexane, or + n-hexane or + n-heptane}. Vapor-liquid equilibria for acetonitrile + methanol at 25° C are reported. The UNIQUAC associated-solution model is used to correlate binary vapor-liquid equilibria and mutual solubilities for the 13 systems constituting the ternary systems and to predict the ternary liquid-liquid equilibria by using binary parameters alone.     

Excess volumes for trichloroethene + benzene, + toluene, + p-xylene, + tetrachloromethane,and + trichloromethane at 303.15 K

Excess volumes V^E for trichloroethene (CCl₂CHCl) + benzene, + toluene, + p-xylene, + tetrachloromethane, and + trichloromethane have been measured at 303.15 K, by direct dilatometry. V^E has been found to be positive for trichloroethene + benzene, and + trichloromethane, and negative for trichloroethene + toluene, and + p-xylene. For trichloroethene + tetrachloromethane V^E is positive at low mole fractions of C₂HCl₃ and negative at high mole fractions.     

Vibration-rotation transition probabilities in CH+ and CD+

Vibrational dipole matrix elements and radiative transition probabilities have been evaluated from electric dipole moment functions for the X¹Σ⁺ states of CH⁺ and CD⁺, which were calculated from highly correlated electronic wavefunctions. The dipole moments in ν = 0 amount to 1.679 D (CH⁺) and 1.313 D (CD⁺), respectively. In comparison to other molecular ions the infrared transition probabilities are found to be rather small. For instance, the Einstein coefficient of spontaneous emission A¹₀ amounts to 1.63 s⁻¹ (CH⁺) and 0.19 s⁻¹ (CD⁺). Dipole moment functions of the neutral CH species in the X²Π and a⁴ Σ⁻ states have also been calculated and are compared with previous theoretical functions.     

Molar excess enthalpies of cis-decalin + benzene, + toluene, +isooctane and +heptane at 298.15 K

Molar excess enthalpies H^E of cis-decalin + benzene, +toluene, +isooctane and +heptane mixtures have been measured by an LKB flow microcalorimeter at 298.15 K. The experimental results are analyzed using the Flory-Patterson-Prigogine theory. The isomer effect of decalin molecule and the effect of the molecular size and shape of the component molecules are discussed.     

Unusually long bonds in CCO+ and COC+

The linear C₂O⁺ isomers CCO⁺ have been studied using ab initio double-zeta basis set SCF calculatuions, and both were found to be structurally unsymmetrical and to have unusually longCCO and COC bond lengths of 1.75 and 1.84 A, respectively. The CO subunit lengths are close to the value for free CO. The C₂O⁺ ions are particularly interesting and merit further study both because of their unusual bonding (resembling that in metal ion-carbonyl complexes) and also because of their potential existence in the interstellar medium and their role in the astrophysically important isotope exchange reaction ¹³C⁺ + O¹²C → ¹³CO + ¹²C⁺.     

Stable CI3+ salts and attempts to prepare CHI2+ and CH2I+

The room-temperature stable CI3+ salts [CI3+[pftb](-)1 and [CI3]+[al-f-al](-) 2([pftb](-) = [Al(OC(CF3)3)4](-); [al-f-al](-) = [((CF3)3CO)3Al-F-Al(OC(CF3)3)3](-)) were prepared in quantitative yields from purified CI4 and the corresponding silver aluminates with total exclusion of light (NMR, IR, UV-VIS, X-ray diffraction). The isolated CI(3)(+) cation is trigonal planar with a sum of <(I-C-I) = 360.0 degrees (1) and 359.9 degrees (2). Attempts to prepare CHI2+ and CH2I+ salts from CHI3 or CH2I2/Ag[pftb] mixtures remained unsuccessful; the reaction with CH2I2 leads to the formation of the adduct [Ag(CH2I2)3]+[pftb](-)3, while for HCI3, dismutation with formation of 1 as well as 3 was observed. All particles were also calculated at the MP2/TZVPP level to predict the vibrational and electronic spectra as well as to calculate the Gibbs free energies of all reactions (DeltaG degrees , gas phase and CH2Cl2 solution). Quantum chemical calculations were also used to investigate the stability of the [pftb](-) anion against the electrophilic attack of the CX3+ and CHnX3-n+ cations (X = F-I, n = 1-3). The strength of the Lewis acidity of these cations and of the isoelectronic boron halides BX()and BHnX3-n have been established on the basis of their fluoride ion affinities (FIAs). The FIAs of the carbon and the boron containing compounds show opposite trends, with fluorinated halomethyl cations being stronger acids than their heavier congeners but iodinated holoboranes being stronger acids than their lighter homologues.     

Speeds of sound and isentropic compressibil- ities of cyclohexane+1,3-dioxolane+2-butanol and n-hexane+1,3-dioxolane+2-butanol

Speeds of sound of the ternary mixtures cyclohexane+1,3-dioxolane+2-butanol and n-hexane+1,3-dioxolane+2-butanol have been measured at the temperatures of 298.15 and 313.15 K. Isentropic compressibilities and excess isentropic compressibilities have been calculated from experimental data. We have also compared the experimental isentropic compressibilities with calculated values from the free length theory and the collision factor theory. Experimental results show positive values of excess isentropic compressibilities in almost the whole composition range for the ternary mixture containing cyclohexane, meanwhile they are negative for the mixture containing n-hexane. Such different behaviour of these systems is related to the large free volume shown by n-hexane. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dynamics of the D+ + H2 and H+ + D2 reactions: a detailed comparison between theory and experiment

An extensive set of experimental measurements on the dynamics of the H(+) + D(2) and D(+) + H(2) ion-molecule reactions is compared with the results of quantum mechanical (QM), quasiclassical trajectory (QCT), and statistical quasiclassical trajectory (SQCT) calculations. The dynamical observables considered include specific rate coefficients as a function of the translational energy, E(T), thermal rate coefficients in the 100-500 K temperature range. In addition, kinetic energy spectra (KES) of the D(+) ions reactively scattered in H(+) + D(2) collisions are also presented for translational energies between 0.4 eV and 2.0 eV. For the two reactions, the best global agreement between experiment and theory over the whole energy range corresponds to the QCT calculations using a gaussian binning (GB) procedure, which gives more weight to trajectories whose product vibrational action is closer to the actual integer QM values. The QM calculations also perform well, although somewhat worse over the more limited range of translational energies where they are available (E(T) < 0.6 eV and E(T) < 0.2 eV for the H(+) + D(2) and D(+) + H(2) reactions, respectively). The worst agreement is obtained with the SQCT method, which is only adequate for low translational energies. The comparison between theory and experiment also suggests that the most reliable rate coefficient measurements are those obtained with the merged beams technique. It is worth noting that none of the theoretical approaches can account satisfactorily for the experimental specific rate coefficients of H(+) + D(2) for E(T)≤ 0.2 eV although there is a considerable scatter in the existing measurements. On the whole, the best agreement with the experimental laboratory KES is obtained with the simulations carried out using the state resolved differential cross sections (DCSs) calculated with the QCT-GB method, which seems to account for most of the observed features. In contrast, the simulations with the SQCT data predict kinetic energy spectra (KES) considerably cooler than those experimentally determined.     

Vapor-liquid equilibria at atmospheric pressure for quinary systems containing n-hexane + ethanol + methylcyclopentane + benzene and either + toluene or + methanol

Values of (p, T, x, y) were determined at 101.325 kPa for each of two quinary systems containing n-hexane + ethanol + methylcyclopentane + benzene and either + toluene or + methanol. The experimental results were compared with those determined from the Wilson equation using parameters obtained from binary results.