Solubilities,densities and refractive indices for the ternary systems ethylene glycol + MCl + H2O (M = Na,K, Rb,Cs) at (15 and 35) °C

The solubilities, densities and refractive indices data for the four ternary systems ethylene glycol + MCl + H₂O (M = Na, K, Rb, Cs) at different temperatures were measured, with mass fractions of ethylene glycol in the range of 0 to 1.0. In all cases, the presence of ethylene glycol significantly reduces the solubility of the salts in aqueous solution. The experimental data of density, refractive index and solubility of saturated solutions for these systems were correlated using polynomial equations as a function of the mass fraction of ethylene glycol. On the other hand, the refractive index and density of unsaturated solutions was also determined for the four ternary systems with varied unsaturated salt concentrations. Values for both the properties were correlated with the salt concentrations and proportions of ethylene glycol in the solutions.     

Modelling (vapour + liquid) and (vapour + liquid + liquid) equilibria of {water (H2O) + methanol (MeOH) + dimethyl ether (DME) + carbon dioxide (CO2)} quaternary system using the Peng–Robinson EoS with Wong–Sandler mixing rule

The (vapour + liquid) equilibria (VLE) and (vapour + liquid + liquid) equilibria (VLLE) binary data from literature were correlated using the Peng–Robinson (PR) equation of state (EoS) with the Wong–Sandler mixing rule (WS). Two group contribution activity models were used in the PRWS: UNIFAC–PSRK and UNIFAC–Lby. The systems were successfully extrapolated from the binary systems to ternary and quaternary systems. Results indicate that the PRWS–UNIFAC–PSRK generally displays a better performance than the PRWS–UNIFAC–Lby.     

Synthesis,characterization and thermochemistry of Cs(ASP) · nH2O (n = 0, 1)

New compounds of aspartic acid Cs(ASP) · nH₂O (n = 0, 1) have been synthesized and characterized by XRD, IR and Raman spectroscopy as well as TG. The structural formula of this new compound was Cs(ASP) · nH₂O (n = 0, 1). The enthalpy of solution of Cs(ASP) · nH₂O (n = 0, 1) in water were determined. With the incorporation of the standard molar enthalpies of formation of CsOH(aq) and ASP(s), the standard molar enthalpy of formation of −(1202.9 ± 0.2) kJ · mol⁻¹ of Cs(ASP) and −(1490.7 ± 0.2) kJ · mol⁻¹ of Cs(ASP) · H₂O were obtained.     

Thermodynamic study of (alkyl esters + α,ω-alkyl dihalides) III. HmEandVmE for 20 binary mixtures {xCu − 1H2u − 1CO2C4H9 + (1 − x)α,ω-ClCH2(CH2)v − 2CH2Cl}, where u = 1 to 4, α = 1 and v = ω = 2 to 6

In this article, the experimental data of excess molar enthalpies $H_{\mathrm{m}}^{\mathrm{E}}$ and excess molar volumes $V_{\mathrm{m}}^{\mathrm{E}}$ are presented for a set of 20 binary mixtures comprised of the first four butyl alkanoates (methanoate to butanoate) and five α,ω-dichloroalkanes (1,2-dichloroethane to 1,6-dichlorohexane), obtained at atmospheric pressure and at a temperature of 298.15 K. The results indicate the existence of specific interactions between both kinds of compounds resulting in exothermic processes for most mixtures, except for those containing butyl methanoate which give rise to net endo/exothermic effects. The $V_{\mathrm{m}}^{\mathrm{E}}$ are positive for mixtures of (butyl esters + 1,2-dichloroethane or 1,3-dichloropropane) and negative for the remaining ones. The change in $H_{\mathrm{m}}^{\mathrm{E}}$ with the dichloroethane chain length for a same ester is regular although the $V_{\mathrm{m}}^{\mathrm{E}}$ presents an irregular variation. It can, therefore, be deuced from this that the mixing process involves both effects, exothermic/endothermic and expansion/contraction, simultaneously. The behaviour of the mixtures is interpreted on the basis of the results observed and attributed to different effects taking place among the molecules studied.To improve application of the UNIFAC model using the version of Dang and Tassios, average values were recalculated again for parameters of the ester/chloride interaction, distinguishing, during its application, the functional group of the acid part of the ester. In spite of this, the model does not adequately reproduce the systems’ behaviour.     

Measurements of the critical parameters for {xNH3 + (1 − x)H2O} with x = (0.9098, 0.7757, 0.6808)

Measurements of the critical parameters for {xNH₃ + (1 ? x)H₂O} with x = (0.9098, 0.7757, 0.6808) were carried out by using a metal-bellows variable volumometer with an optical cell. The expanded uncertainties (k = 2) in temperature, pressure, density, and composition measurements have been estimated to be less than 3.2 mK, 3.2 kPa, 0.3 kg · m^?3, and 8.8 · 10^?4, respectively. In each mole fraction, the critical temperature T_c was first determined on the basis of the intensity of the critical opalescence. The critical pressure p_c and critical density ρ_c were then determined as the point at which the meniscus disappears on the isotherm at T = T_c. The expanded uncertainties (k = 2) in the present critical parameters have also been estimated. Comparisons of the present values with the literature data as well as the calculated values afforded using the equation of state are also presented.     

The (p, ρ, T) properties and apparent molar volumes Vϕ of (ZnBr2 + C2H5OH)

The (p, ρ, T) properties and apparent molar volumes V_? of ZnBr₂ in ethanol at temperatures (293.15 to 393.15) K and pressures up to p = 40 MPa are reported. The measurements were made with a recently developed vibration-tube densimeter. The system was calibrated using double-distilled water, methanol, ethanol, and aqueous NaCl solutions. The experiments were carried out at molalities of m = (0.05681, 0.16958, 0.30426, 0.43835, 0.93055, 1.49016, and 1.88723) mol · kg^?1 using zinc bromide. An empirical correlation for the density of (ZnBr₂ + C₂H₅OH) with pressure, temperature, and molality has been derived. This equation of state was used to calculate other volumetric properties such as isothermal compressibility, isobaric thermal expansibility, the differences in specific heat capacities at constant pressures and volumes, apparent molar volumes of ZnBr₂ in ethanol, and partial molar volumes of both components.     

Thermodynamics of the O2/O2− redox couple in molten (LiCl + KCl + Li2O) systems

Activity coefficients of oxide ion were determined by the measurements of the standard formal potential of O₂/O^2? with a boron-doped diamond (BDD) electrode in molten (LiCl + KCl): LiCl:KCl = {58.5:41.5 (eutectic), 65:35, 70:30, 75:25} mol% at T = (673 to 803) K. The activity coefficient decreases with the increase of the LiCl content in the melt: (18.7 ± 1.5, 7.7 ± 1.0, 4.1 ± 0.4, and 1.6 ± 0.1), respectively, at T = 773 K in each melt. The result is explained by the attractive force between Li⁺ and O^2? which is stronger than that between K⁺ and O^2?.     

(Vapour + liquid) equilibria for the binary mixtures (cis-pinane + α-pinene) and (cis-pinane + 1-butanol)

The isothermal and isobaric (vapour + liquid) equilibria for (cis-pinane + α-pinene) and (cis-pinane + 1-butanol) measured with an inclined ebulliometer are presented. The experimental results are analysed using the UNIQUAC equation with the temperature-dependence binary parameters with satisfactory results. Experimental vapour pressures of cis-pinane are also included.     

Hyperconjugation versus back bonding in AH3−nXn species (A = Si and Ge; X = F,Cl and Br; and n = 1, 2 and 3)

In this research two competing phenomena, back bonding and hyperconjugation, have been investigated based on Natural Bond Orbital (NBO) and Atoms in Molecules (AIM) analyses for radical AH_3?nX_n species, where A = Si and Ge, and n = 1, 2 and 3. It is demonstrated in this article that both above phenomena will be occurred significantly, while back bonding is the only event in analogous compounds with carbon and hyperconjugation is rather negligible. It was also found that only one back bonding with the help of keyword $CHOOSE in NBO analysis can be found in this type of compounds with reasonable structure, while it can be sometimes detected in AH_3?nX_n without using keyword $CHOOSE. It is also shown that there is always an increase in bond length in comparison with reference molecules in mentioned species due to existing hyperconjugation, while if the central atom is carbon, we have always a decrease of bond length due to only having back bonding. Additionally, from AIM point of view, the delocalization indices for α-spin (majority spin) is more than β-spin (minority spin) in radical species for molecules without back bonding, while the situation in our compounds is quite reverse, which can be attributed to the π back bonding in the β-spin electrons.     

Synthesis,characterization and reactions of the transition metal halogenoalkyl carbocation complexes [Cp(CO)2M{η2-CH2CH(CH2)nX}]PF6 (n = 1–8, 10, M = Fe; n = 3, 4 M = Ru; X = Br,I)

The halogenoalkyl complexes [Cp(CO)₂M{(CH₂)_nX}] (n = 3–10, 12, M = Fe; n = 5, 6, M = Ru, X = Br, I) react with Ph₃CPF₆ in dry CH₂Cl₂ to give the corresponding carbocation complexes [Cp(CO)₂M{η²-(CH₂CH(CH₂)_n?2X}]PF₆ in high yields. NMR evidence indicates that the metals form metallacyclopropane type structures with the carbocation ligand. The reactions of some of the cationic complexes with NaI, PPh₃, Na[Cp(CO)₂Fe] and Et₃N are discussed. NaI and Na[Cp(CO)₂Fe] displace the halogeno-olefin, while PPh₃ adds at the β-CH^δ+ giving the unstable phosphonium adducts [Cp(CO)₂Fe{CH₂CH(PPh₃)(CH₂)_n?2X}]PF₆ which decompose to the halogeno-olefins and the cationic PPh₃ complex [Cp(CO)₂Fe(PPh₃)]⁺. Et₃N causes allylic deprotonation forming internal olefin complexes of the type [Cp(CO)₂Fe{CH₂CHCH(CH₂)_n?3X}]PF₆.     

(p, ρ, T) measurements of (ammonia + water) in the temperature range 310 K to 400 K at pressures up to 17 MPa. II. Measurements of{ xNH3 + (1 − x )H2O } at x = (1.0000, 0.8374, 0.6005, and 0.2973)

Measurements of (p, ρ, T) for{xNH₃ +  (1  − x)H₂O} at x =  (1.0000, 0.8374, 0.6005, and 0.2973) and at specified temperatures and pressures in the compressed liquid phase were carried out with a metal-bellows variable volumometer between T =  310 K and T =  400 K at pressures up to 17 MPa. The results cover the high-density region from ρ =  345 kg · m ^− 3 for x =  1.0000 to ρ =  878 kg · m  ^− 3for x =  0.2973. The experimental uncertainties at a 95 per cent confidence interval in temperature T, pressure p, density ρ, and mole fraction x were estimated to be less than  ± 11 mK,  ± 2.6 kPa,  ± 2.1 · 10  ^− 3. ρ, and  ± 1.8 · 10 ^− 3· x, respectively. A detailed comparison of the density values with literature data as well as with an equation of state proposed by Tillner-Roth and Friend is also reported.     

Phosphasilaallenes >Si = C = P− and phosphagermaallenes >Ge = C = P−

Phosphasilaallene Tip(Ph)Si = C = PMes* (Tip = 2,4,6-triisopropylphenyl, Mes* = 2,4,6-tri-tert-butylphenyl) and phosphagermaallene Mes₂Ge = C = PMes* (Mes = 2,4,6-trimethylphenyl) have been obtained by dehalogenation of their corresponding dihalophosphametallapropenes > E(X)-C(X′) = P? by tert-butyllithium. They dimerize above ?40 °C by a cycloaddition involving two E = C double bonds or the E = C and the P = C double bonds but can be characterized at low temperature by trapping reactions and by low field shifts in ³¹P, ²⁹Si and particularly ¹³C NMR for the sp carbon atom. Owing to a small increase in the steric hindrance, phosphagermaallene Tip(t-Bu)Ge = C = PMes* can be stabilized and isolated. The Ge = C double bond undergoes nearly quantitative [2 + 1] cycloadditions with chalcogens and [2 + 2] cycloadditions with aldehydes or ketones. The surprisingly stable lithiochlorosilane R(Cl₂)Si-C(Li) = PMes* (R = 9-methylfluorenyl) behaves as a synthetic equivalent of the phosphasilaallene R(Cl)Si = C = PMes*. With two alkyl groups (t-Bu) on the germanium atom, the phosphagermaallene t-Bu₂Ge = C = PMes* is not obtained but its formal dimers 1,3-digermacyclobutanes have been isolated.     

Ternary (liquid + liquid) equilibria for (water + 2-propanol + α-pinene,or β-pinene) mixtures at four temperatures

Ternary (liquid + liquid) equilibria date for the (water + 2-propanol + α-pinene, or β-pinene) systems were measured at T = (293.15, 298.15, 303.15, and 308.15) K under atmospheric pressure. The experimental results were correlated using the extended and modified UNIQUAC models. The calculated results obtained from the modified UNIQUAC model successfully represent the experimental tie-line data. The temperature influence on liquid-phase equilibria was studied.