Interactions of metal extractant reagents: VII. Aggregation of tri-n-dodecylammonium chloride and perchlorate in toluene at 40°C

The self-association and mixed species formation equilibria of tri-n-dodecylammonium chloride (TLAHCl) and tri-n-dodecylammonium perchlorate (TLAHClO₄) dissolved in toluene have been studied by vapor pressure osmometry at 40°C. The experimental data can be fitted best by the formation of the aggregates (TLAHCl)₂ (log _2,0=1.35±0.06), (TLAHClO₄)₂ (log _0,2=2.4±0.1) and the mixed species (TLAHCL) (TLAClO₄)₂ (log _1,2=6.4±0.5), (TLAHCl)₂(TLAHClO₄)(log _2,1=7.1±0.6) and (TLAHCl)₂(TLAHClO₄)₂ (log _2,2=9.9±0.7).     

Interactions of metal extractant reagents. V: The aggregation of tri-n-dodecylammonium hydrogenchromate and hydrogensulphate dissolved in toluene at 40°C

The aggregation equilibria of tri-n-dodecylammonium hydrogensulphate (TLAH ₂ SO ₄ ) and hydrogenchromate (TLAH ₂ CrO ₄ ) dissolved in toluene have been studied by vapor pressure osmometry at 40°C. The experimental data can be best fit by the formation of the species (TLAH ₂ SO ₄ ) ₄ (log ₄ = 6.3 ± 0.2) and (TLAH ₂ SO ₄ ) ₅ (log ₅ = 8.0 ± 0.2) in the acid sulphate system and (TLAH ₂ CrO ₄ ) ₂ (log ₂ = 0.75 ± 0.07) in the acid chromate one.     

Thermodynamics of aqueous gallium chloride. Heats of solution and dilution at 25°C

The heat of solution of GaCl₃ and heats of dilution of single GaCl₃ solutions in water and of mixed GaCl₃−HCl solutions in HCl solutions (with a fixed HCl concentration of 0.1337 mol-kg⁻¹ HCl) up to 4 mol-kg⁻¹ GaCl₃ were measured at 25°C. While in the acid solutions hydrolysis is suppressed to below 0.5% of total gallium concentration, the measurements in water allow evaluation of the effect of hydrolysis on the relative enthalpy. The Pitzer interaction model for excess properties of aqueous electrolytes was used to interpret the change in relative enthalpy with concentration. Pitzer parameters were derived by statistical inference using ridge regression. Their physical significance is supported by the heat of solution data. The measurements yield the following results for standard heats of formation and Pitzer parameters for the relative molar enthalpy at 25°C: With these parameters the overall variance in the partial molar heat of solution at infinite dilution, extrapolated from the present experiments, is minimized to 0.35 kJ²-mol⁻², while the experimental apparent molar heats of dilution are reproduced on average within 2.7 kJ-mol⁻¹.     

Luminescence of toluene and deuterium-substituted toluenes at 77°K in polycrystalline methylcyclohexane

The luminescence spectra of C₆H₅CH₃, o-, m- and p-DC₆H₄CH₃, C₆H₅CD₃, C₆D₅CH₃ and C₆D₅CD₃ in polycrystalline methylcyclohexane at 77°K have been studied. The vibrational analyses of the phosphorescences and fluorescences of these isotopically related molecules are reported. For the phosphorescences, progressions in a totally symmetric ring carbon—carbon stretching frequency, based mainly on one quantum of a non-totally symmetric vibration of e_2g parentage in benzene, are interpreted to signify a planar, non-regular hexagon ring structure for the lowest triplet state of the toluenes. In the fluorescences, progressions in the ring breathing mode, with a different e_2g mode of benzene serving as a false origin, are suggestive of an expanded regular hexagon ring geometry of the lowest excited singlet state.     

Liquid—liquid equilibria for the methanol—toluene—n-octane and methanol—toluene—n-hexane systems at 25°C

Ternary liquid—liquid equilibrium data have been measured for the methanol—toluene—n-octane and the methanol—toluene—n-hexane systems at 25°C. The results have been correlated using a modified Wilson equation.     

Thermodynamic properties of transition metals in aqueous solution: 1. The enthalpies of dilution of some aqueous transition metal chloride solutions at 25°C

Enthalpies of dilution H _D of aqueous solutions of the transition metal chlorides CdCl₂, CoCl₂, CuCl₂, MnCl₂, and NiCl₂ were measured from 1.0 molal to dilute solution at 25°C. The apparent molal enthalpy equations of Pitzer were then fit to the resulting H _D data and the parameters for these equations are presented. The heat of dilution data for CdCl₂ and CuCl₂ were in good agreement with results by other workers.     

Enthalpies of dilution of tris-ethylenediaminocobalt(III) chloride in aqueous solution at 25°C

The enthalpies of dilution for aqueous solutions of [Co(en)₃]Cl₃, where en=1,2-diaminoethane, have been measured at 25°C, and up to m=1 mol-kg^–1, using a new large isoperibol calorimeter by the long-jump method. Relative apparent molar enthalpies L have been extracted as an empirical equation relating L and m. Comparison with other 31 and 13 aqueous systems confirms the previously suggested hydrophobic character of the [Co(en)₃]³⁺ cation.     

Study of the behavior of chromium(III) in potassium nitrate solutions at 25°C

Solubility in the KNO₃-Cr(NO₃)₃-H₂O system at 25°C was studied by an isothermal method. The existence of solid phases of potassium nitrate and chromium(III) nitrate nonahydrate was confirmed by constructing a phase diagram, chemical analysis, and IR spectroscopy. Crystallization of potassium nitrate from aqueous solutions was studied. Potassium nitrate does not interact with chromium(III) nitrate within the range of micro and macro concentrations. The capture of chromium(III) by KNO₃ crystals is due to adsorption and occlusion of a mother solution.     

Phase equilibria and salting-out effects in a cesium nitrate-triethylamine-water system at 5–25°C

Phase equilibria and critical phenomena in a cesium nitrate-water-triethylamine system in which the constituent binary liquid system is stratified at the lower critical solution temperature (LCST) is studied in a range of 5–25°C by the visual polythermal method. It is found that introducing cesium nitrate into the water-triethylamine system leads to a slight reduction in the LCST (from 18.3 to 16.3°C) and to a decrease in the mutual solubility of the components. The distribution coefficients of triethylamine between aqueous and the organic phases of the monotectic state at different temperatures are calculated. It is found that the salting-out of triethylamine from aqueous solutions by cesium nitrate increases with rising temperature. The results of the salting-out effect of sodium, potassium, and cesium nitrates on a water-triethylamine binary system are compared.     

Spectrophotometric study of Nd,Sm, and Ho complexation in chloride solutions at 100–250°C

Complex formation in Ln chloride solutions is studied by spectrophotometric method. Electronic absorption spectra of Nd³⁺, Sm³⁺, and Ho³⁺ ions are measured in the range of supersensitive transitions in solution with Cl^– ion concentration from 0 to 5 mol/l in 100–250°C temperature interval under saturated vapor pressure. The Nd and Sm spectra represent integrated curves that mainly consist of Ln³⁺ and LnCl²⁺ absorption bands (with stability constant ₁), while the Ho spectra consist of Ho³⁺ and HoCl ₂ ⁺ absorption bands (with ₂). The stability constants ₁ and ₂ calculated for each wave number by linear regression method acquire steady values and have the meaning of the best unbiased linear estimates. Thermodynamic values of log₁ for Nd, Sm, and Ho monochlorides lie in a narrow interval at constant temperature. In the case of Nd and Sm, the temperature curves of log₁ and log₂ have smaller slopes as compared to that of Ho, which is explained by the effect of a covalent component in their spectra that adds to the ionic nature of the bonds in monochloride complexes. The ₂ values increase in the order Nd相似文献   

Stability,spectra and structure of the cobalt(II) chloride complexes in hexamethylphosphoramide solution at 25°C

Cobalt(II) chloride complexes were investigated spectrophotometrically in hexamethylphosphoramide (HMPA) solutions. It has been established that four consecutive tetrahedral chloro complexes of cobalt(II) are formed in the Co(ClO₄)₂-CoCl₂ and CoCl₂-LiCl-HMPA solutions. The formation constants of the complexes have been calculated: log K₁ = 9.0 (±0.5), log K₂ = 6.5 (±0.5), log K₃ = 3.05 (±0.05) and log K₄ = − 1.42 (±0.03). The high stability of the dichloro-complex results in the fact that this species is the only complex of cobalt(II) existing in HMPA solutions of CoCl₂.     

Solubility of gases in liquids. 18. High-precision determination of Henry fugacities for argon in liquid water at 2 to 40°C

The solubility of argon in pure liquid water was measured at ca. 100 kPa and from 2 to 40°C using an analytical method characterized by an imprecision of about ±0.05%. From the experimental results, Henry fugacities H _2,1 (T,P _s,1 ) (also known as Henry's Law constants or Henry coefficients) at the vapor pressure P _s,1 of water as well as Ostwald coefficients L _2,1 at infinite dilution were obtained. Measurements were made at roughly 0.5°C and/or 1° intervals between 2 and 8°C (region I), and at 5°C intervals above 10°C (region II). A difference plot lnH _2,1 /T suggests an unusual temperature dependence in region I, i.e., between 2 and 8°C. Because of this, the data were treated separately in two parts corresponding to these two regions. Our results are compared with the recent high-precision data of Krause and Benson (Henry fugacities), and with calorimetrically determined quantities (enthalpies and heat capacities of solution). Finally, experimental results are compared with values calculated via scaled particle theory.Communicated in part at the 2^nd International Symposium on Solubility Phenomena in Newark, New Jersey, August 12–15, 1986, and at the 4^th ISSP in Troy, New York, July 20–August 3, 1990.     

Micellar properties of tetradecyltrimethylammonium nitrate in aqueous solutions at various temperatures and in water-benzyl alcohol mixtures at 25 °C

The micellar properties of tetradecyltrimethylammonium nitrate (C14TANO₃) in aqueous solutions in the temperature range of 10 to 35 °C and in aqueous solutions of benzyl alcohol (BzOH) at 25 °C were studied conductometrically. The specific conductivity data served for the evaluation of critical micelle concentration, cmc, and the degree of ionization of the micelles, , of the surfactant. From the temperature dependence of the cmc the thermodynamic parameters for micellization of C14TANO₃ were calculated by applying Mullers modified equation. BzOH was found to affect strongly the cmc and values of the surfactant. The plot of the cmc/cmc_o ratio (where cmc_o is for pure water) as a function of BzOH molality, exhibits a characteristic break, which was attributed to the commencement of self-association of BzOH in aqueous solution at a molality of ca. 0.05. By applying the theoretical treatment suggested by Motomura for binary surfactant systems, the molar fraction of BzOH in the micelles at cmc, was estimated as a function of molality of the alcohol. C14TANO₃ appears to be slightly more hydrophobic compared to the corresponding bromide.     

Phase equilibria in the fluorosilicic acid-o-phenylenediamine-water system at 25°C: The crystal structure of o-phenylenediammonium hexafluorosilicate

The interactions in the H₂SiF₆-o-phenylenediamine-H₂O (FSA-PDA-H₂O) system at 25°C is studied using the isothermal solubility method. The solid phases existing in the system are o-PDA (0-23.70 wt % H₂SiF₆) and hexafluorosilicate formulated as (o-PDAH₂)SiF₆ (23.70–44.60 wt % H₂SiF₆). The structure for the latter is solved in single-crystal X-ray diffraction experiments. In the ionic structure of the complex, o-PDAH ₂ ²⁺ cations and SiF ₆ ² anions are linked through H-bonds NH-F((N-F 2.865(2)-2.967(2) Å) into a two-dimensional net. The Si-F bond lengths are 1.6709(12)-1.6958(12) Å.     

Fractal analysis of pit morphology of Inconel alloy 600 in sulphate,nitrate and bicarbonate ion-containing sodium chloride solution at temperatures of 25–100 °C

Pit morphology of Inconel alloy 600 in sulphate (SO₄ ^2-), nitrate (NO₃ ^-) and bicarbonate (HCO₃ ^-) ion-containing 0.5 M sodium chloride (NaCl) solution was analysed in terms of fractal geometry as functions of solution temperature and anion concentration using the potentiostatic current transient technique, scanning electron microscopy, image analysis and ac-impedance spectroscopy. Potentiostatic current transients revealed that the pitting corrosion is facilitated by the increase in solution temperature, irrespective of anion additives, and that it is hindered by the increase in NO₃ ^- and HCO₃ ^- ion concentration, regardless of solution temperature. Above 60 °C, it was also found that the addition of SO₄ ^2- ions impedes pit initiation, but enhances pit growth. The value of fractal dimension D _f of the pits increased with increasing solution temperature and with decreasing NO₃ ^- and HCO₃ ^- ion concentration. Moreover, the value of D _f increased above 60 °C with increasing SO₄ ^2- ion concentration. This is caused by the increase in the ratio of pit perimeter to pit area, implying the formation of pits with micro-branched shape due to the acceleration of the local attack in the pits. From the decrease of the depression parameter with increasing solution temperature, it is inferred that the roughness of the pits increased with increasing solution temperature. In addition, the depression parameter was found to increase with increasing NO₃ ^- and HCO₃ ^- ion concentration. But, above 60 °C, in the case of SO₄ ^2- ion addition, the depression parameter decreased with increasing SO₄ ^2- ion concentration. From the experimental findings, the three-dimensional pit morphology is discussed in terms of the values of D _f of the pits and the depression parameter, with respect to anion concentration and solution temperature.     

Ternary phase equilibria for the sodium chloride–sodium sulfate–water system at 200 and 250 bar up to 400°C

Phase equilibria in the NaCl–Na₂SO₄–H₂O system were investigated at 200 and 250 bar for total salt concentrations ranging from 5 to 20 wt.% total salt over temperatures ranging from 320 to 400°C. In addition to providing data for this ternary system, the experiments also added information on the phase behavior of the two binary systems: NaCl–H₂O and Na₂SO₄–H₂O. For salt mixture compositions which were rich in sodium sulfate, a solid phase was observed to nucleate from the homogeneous liquid phase. Salt mixture compositions which had a high fraction of sodium chloride exhibited a vapor separation from a homogeneous liquid phase. By fitting curves to the solid–liquid and vapor–liquid separation temperatures, the temperature and composition of a constrained invariant point where liquid, solid salt and vapor are in equilibrium were estimated. These estimates were performed at discrete compositions of 5, 10, 15 and 20 wt.% total salt at pressures of 200 and 250 bar. The temperature and composition of the invariant point increased with increasing pressure following a simple thermodynamic model for boiling point elevation in a nearly ideal solution.     

Dielectric Study of Charge-transfer Complexes in Binary and Ternary Systems at 35°C

Abstract

The measurements of dielectric constant of a number of binary and ternary mixtures of butyl acetate, butyl alcohol, quinoline, pyridine and o-cresol in carbon tetrachloride and benzene have been made at 35°C. Molecular interaction of these aromatic compounds have been studied in terms of variations in parameters; ‘dipole moment’ (μ), ‘interaction dielectric constant’ (δ?), ‘molecular polarisation’ (P) and ‘excess polarisation’ (P_E ). The dipole moment has been calculated using Hysken's method, the interaction dielectric constant utilizing the equation of ideal mole fraction law and excess polarisation using the theory of Erap and Glasstone. The positive values of δ?₁₂ for binary mixtures of quinoline and butyl acetate in carbon tetrachloride and benzene have been attributed to the formation of charge transfer complexes. The negative values of δ?₁₂ and δ?₁₂₃ with pyridine suggest that charge transfer interaction is weakened by pyridine in its binary and ternary mixtures. The plot between the excess polarisation value and the product of mole fractions yielded a straight line passing through the origin showing the formation of charge transfer complexes.     

Activity and Osmotic Coefficients from the Emf of Liquid Membrane Cells. IX: Mn(ClO4)2 and MnSO4 in Water at 25°C

The relative activity coefficients of MnSO₄ and Mn(ClO₄)₂ were measured downto about 5×10^–5 mol-kg^–1 by means of cells with ion-exchange liquid membranes.The measurements at high dilution provide an answer to the age-old problem ofabsolute values of the activity coefficients for MnSO₄. They also lead to acorrection of the activity coefficients for Mn(ClO₄)₂, whose literature values arefound to be biased by ca. 6.5%. Like other bivalent metal sulfates, MnSO₄does not obey the Debye—Hückel law inasmuch as negative instead of positivedeviations from the limiting law are observed in the dilute regions. The possibilityfor this kind of behavior to denote ion association is discussed. The best-fitparameters of Pitzer's equation, able to provide accurate values of the activityand osmotic coefficients of the two salts for any concentration, are reported.     

Oxychlorination of methane to methyl chloride at 300°C in the system palladium(II) complexes-heteropolyacids-silica gel

The activity of systems, applied to silica gel from chloride solutions, in the oxychlorination of CH₄ to CH₃Cl at 300° Cincreases in the order H₃[PMo₁₂O₄₀]9[PMo₆V₆O_40]2(PdCl₂-H₉[PMo₆V₆O₄₀] (or H₃[PMo₁₂O₄₀]))<(PdCl₂-Na_nH_9–n[PMo₆V₆O₄₀]). Additions of NaCl (molar ratio of the components NaClSiO₂7100) lead to an increase in the yield of CH₃Cl. The mechanisms of CH₄ oxidation have been discussed which are electrophilic with the participation of Pd(II) complexes and involve chlorides with the participation of surface Cl atoms.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 31, No. 1, pp. 29–33, January–February, 1995.