Physicochemical properties of KOH-H<Subscript>2</Subscript>O<Subscript>2</Subscript>-H<Subscript>2</Subscript>O solutions

Density, viscosity, and surface tension of KOH-H₂O₂-H₂O solutions used to synthesize potassium superoxide in sprayer apparatus were studied with various relative amounts of the components in the temperature range 0–30°C. Analytical dependences of the above-mentioned quantities on temperature and solvent (water) content of the system were found.     

Anionic complexes as products of reactions in SO<Subscript>2</Subscript>-carbamide(acetamide)-H<Subscript>2</Subscript>O systems

Evaluation of the contribution of hydrosulfite and pyrosulfite ions in the formation of anionic complexes in the sulfur(IV) oxide-amide-water systems was carried out considering the data of the pH-metric and redox-metric studies. Microconstants of the formation of anionic complexes of carbamide and acetamide with the above-mentioned anions were calculated.     

Solubility isotherm for the Na<Subscript>2</Subscript>MoO<Subscript>4</Subscript>-Na<Subscript>2</Subscript>SO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O system

Solubility in the Na₂MoO₄-Na₂SO₄-H₂O system was studied using isothermal saturation at 5–100°C. The boundaries of crystallization fields were determined for sodium sulfate and sodium molybdate. Solid solutions were not observed within the range of the temperatures studied. The density, refractive index, and dynamic viscosity of the saturated solutions of the system were determined, and these data were used to calculate the molar volume, kinematic viscosity, and apparent molar volume of the sum of salts in these solutions. All property isotherms of solutions are in a strict correlation with the solubility in the system; this correlation is represented as an isobaric-isothermal diagram.     

Interactions in the system Mn(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-HCONH<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

Solubilities and solid phases in the system Mn(NO₃)₂-HCONH₂-H₂O were studied by an isothermal method at 25°C. The congruently saturating compound Mn(NO₃)₂ · 2HCONH₂ · 2H₂O was isolated; the concentration conditions for its crystallization in the system were determined. The solid phases of the system were characterized by physicochemical methods (X-ray powder diffraction, differential thermal analysis, IR spectroscopy, and crystal-optical analysis).     

Specific features of the thermodynamics of activation in the LaNi<Subscript>5</Subscript>-H<Subscript>2</Subscript> and CeNi<Subscript>5</Subscript>-H<Subscript>2</Subscript> systems

Using heat conducting Tian—Calvet calorimetry and volumetric measurements, the first hydrogen absorption—desorption cycles in the LaNi₅-H₂ and CeNi₅-H₂ systems were studied. The pressure—composition isotherms were plotted, the equilibrium pressures of hydrogen along the absorption and desorption branches and in the region of hysteresis for different activation steps were determined, and the enthalpies of phase transitions α → β and β → α were calculated. The profiles of the heat evolution curves were analyzed. It was concluded that the mechanism of the reactions studied changes upon activation.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 134–139, January, 2005.     

Kinetics of the oxidation of diethyl sulfide in the B(OH)<Subscript>3</Subscript>-H<Subscript>2</Subscript>O<Subscript>2</Subscript>/H<Subscript>2</Subscript>O system

Data obtained for the kinetics of oxidation of diethyl sulfide (Et₂S) by hydrogen peroxide in aqueous solution catalyzed by boric acid indicate that monoperoxoborates B(O₂H)(OH) ₃ ⁻ and diperoxoborates B(O₂H)₂(OH) ₂ ⁻ are the active species. The rates of the reactions of Et₂S with B(O₂H)(OH) ₃ ⁻ and B(O₂H)₂(OH) ₂ ⁻ are 2.5 and 100 times greater than with H₂O₂. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 1, pp. 38–42, January–February, 2007.     

K<Subscript>2</Subscript>SO<Subscript>4</Subscript>-K<Subscript>2</Subscript>HPO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O phase diagram in the region of heterogeneous supercritical fluids

Our experimental study of phase equilibria in the K₂SO₄-K₂HPO₄-H₂O system at temperatures up to 500°C and pressures up to 100 MPa was directed to determine the sequence of phase transformations that generate heterogeneous supercritical fluids whose existence region propagates from the K₂SO₄-K₂HPO₄-H₂O subsystem into the ternary system. We found that supercritical fluids become heterogeneous as a result of addition of K₂HPO₄ starting with l ₁-l ₂ critical phenomena in saturated solutions, with the attendant amalgamation of the stable immiscibility region that propagates from the K₂HPO₄-H₂O system and the metastable liquid-liquid phase separation that originates from the K₂SO₄-H₂O system. Our experimental results and the topological analysis of phase equilibria in the vicinity of the critical point of water gave us the full scenario of the phase behavior of the title ternary system in the region of the subcritical and supercritical parameters of state.     

Preparation and physicochemical study of nickel(II) thiostannate in the NiCl<Subscript>2</Subscript>-SnS<Subscript>2</Subscript>-H<Subscript>2</Subscript>O system

Nickel(II) thiostannate is prepared in the NiCl₂-SnS₂-H₂O system by precipitation from solutions. Its formation temperature and homogenization time are determined. The synthesis of NiSnS3 from the ammonium acetate buffer solution is found to last 6–8 h at 80–90°C. The elemental composition of ternary nickel(II) thiostannate is detrermined by chemical analysis.     

Glass formation in the Al<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>-Al(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

Glass formation boundaries in the Al₂(SO₄)₃-Al(NO₃)₃-H₂O system were determined. IR spectra were studied. Schemes of structural rearrangements within the boundaries of a second glass formation region in the Al(NO₃)₃-H₂O binary subsystem are suggested. A structure is suggested for glassy Al(NO₃)₃H₂O.     

Dual course of bisacetonation of D-xylose in a system Me<Subscript>2</Subscript>CO-Me<Subscript>2</Subscript>C(OMe)<Subscript>2</Subscript>-H<Subscript>2</Subscript>SO<Subscript>4</Subscript>

In the course of formation of a bisisopropylidene protective group by keeping D-xylose in a mixture Me₂CO-(MeO)₂CMe₂-H₂SO₄ alongside the expected 1,2:4,5-O-diisopropylidene derivative formed minor dimethylacetal, 2,3:4,5-O-diisopropylidene-D-xylose, inseparable from the main product by the chromatography on SiO₂. The conditions were found for the selective formation and isolation of the latter, some its one-pot transformations were studied resulting in synthetically promising orthogonally protected acyclic C⁵-synthons.     

Ternary water-salt system Sm(CCl<Subscript>3</Subscript>COO)<Subscript>3</Subscript>-Er(CCl<Subscript>3</Subscript>COO)<Subscript>v</Subscript>-H<Subscript>2</Subscript>O at 298 K

The system of samarium and erbium trifluoroacetates and water has been studied by the isothermal solubility technique at 298 K. The composition of the solids has been determined using the Schreinemakers wet residue technique. The refractive indices, specific volumes, and viscosities of liquid phases and the refractive indices of solid residues have been determined. A continuous solid solution is found to form in the system. Some thermodynamic parameters have been determined for this solid solution.     

Liquid-solid metastable phase equilibria for the quaternary system (NaCl-KCl-CaCl<Subscript>2</Subscript>-H<Subscript>2</Subscript>O) at 308.15 K

The solubility and the physicochemical properties (densities, viscosities, refractive indices, conductivities and pH) in the liquid-solid metastable system (NaCl-KCl-CaCl₂-H₂O) at 308.15 K have been investigated using the isothermal evaporation method, and the dry-salt phase diagram, water-phase diagram, and the diagram of physicochemical properties vs. composition in the system were plotted. One three-salt cosaturated point, three metastable solubility isotherm curves, and three crystallization regions corresponding to sodium chloride, potassium chloride and calcium chloride tetrahydrate were formed, and neither solid solution nor double salts were found. On the basis of the extended Harvie-Weare (HW) model and its temperature-dependent equation, the values of the Pitzer parameters β⁽⁰⁾, β⁽¹⁾, C ^ϕ for NaCl, KCl and CaCl₂, the mixing ion-interaction parameters θ_Na,K, θ_Na,Ca, θ_K,Ca, Ψ_Na,K,Cl, Ψ_Na,Ca,Cl, Ψ_K,Ca,Cl, and the Debye-Hückel parameter A ^ϕ and the chemical potentials of the minerals in the quaternary system at 308.15 K were fitted, and the predictive solubility based on the temperature-dependent equation and the chemical potentials of the minerals agrees well with the experimental data.     

Glass formation in the Al(IO<Subscript>3</Subscript>)<Subscript>3</Subscript>-Al<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>-HIO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

On the basis of experimental data obtained in the study of glass-formation boundaries in the Al₂(SO₄)₃-HIO₃-H₂O, Al(IO₃)₃-Al₂(SO₄)₃-H₂O, and Al(IO₃)₃-HIO₃-H₂O systems and using geometrical analysis, we predict the positions of glass-formation boundaries in the Al(IO₃)₃-Al₂(SO₄)₃-HIO₃-H₂O four-component system along 60, 40, and 25 wt % H₂O sections.     

Study of the crystallization fields of cobalt(II) slenites in the system CoSeO<Subscript>3</Subscript>-SeO<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

Summary The solubility of CoSeO₃-SeO₂-H₂O system in the temperature region 298-573 K was studied. The phase diagram of cobalt(II)selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, CoSeO₃×2H₂O, α-CoSeO₃×1/3H₂O, β-CoSeO₃×1/3H₂O, CoSeO₃, Co(HSeO₃)₂×2H₂O and CoSe₂O₅ were obtained. The different phases were proved and characterized by chemical and X-ray analyses, as well as IR spectroscopy.     

Phase composition,formation parameters,and morphology of precipitates in the LiVO<Subscript>4</Subscript>-VOSO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O system

The phase and chemical compositions of the precipitates formed in the LiVO₃-VOSO₄-H₂O system at initial pH within 1 ≤ pH ≤ 4 and 90°C were studied. The following phases were prepared: an α phase Li_1.4(VO)_1.3[H₂V₁₀O₂₈] · nH₂O and a β phase Li_{0.6 ? x} H_{1.4 + x} [V₁₂O_{31 ? y/2}] · nH₂O (0 ≤ x ≤ 0.5, 1.3 ≤ y ≤ 2.0) with a layered structure. Li_0.4V₂O₅ · H₂O nanorods with the interlayer distance 10.30 ± 0.08 Å were synthesized at 180°C in an autoclave. The morphology, IR spectra, and main formation processes for these polyvanadates were studied.     

Solid solutions in the system Nd(CCl<Subscript>3</Subscript> COO)<Subscript>3</Subscript>-Y(CCl<Subscript>3</Subscript> COO)<Subscript>3</Subscript>-H<Subscript>2</Subscript> O at 298 K

The water-salt system consisting of neodymium and yttrium trichloroacetates is studied by the isothermal solubility method at 298 K. The compositions of solid phases are determined by the Schreinemakers wet residues technique. Refractive indices, specific volumes, and viscosities for liquid phases and refractive indices of crystals for solid phases are determined. Continuous solid solutions are found in the system; some their thermodynamic characteristics are calculated.     

Effect of competitive acido complex formation of the solubility of binary chlorides in MCl<Subscript>2</Subscript>-M′Cl<Subscript>2</Subscript>-H<Subscript>2</Subscript>O systems

The solubility of d-metal halides in MCl₂-M′Cl₂-H₂O systems with competitive complex formation at 25°C was discussed. The role of complex formation and hydration was traced. As the stability constants become closer to each other, the salting-in regions in the crystallization braches of both chlorides disappear. Original Russian Text I.V. Zamyatin, M.Yu. Skripkin, 2007, published in Zhurnal Obshchei Khimii, 2007, Vol. 77, No. 2, pp. 252–259.     

Glass formation in the system Al(IO<Subscript>3</Subscript>)<Subscript>3</Subscript>-HIO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O

Glass-formation features in the system Al(IO₃)₃-HIO₃-H₂O are discussed, and the boundaries of the glass field are determined.     

Phase equilibria and heterogenization of supercritical fluids in the K<Subscript>2</Subscript>SO<Subscript>4</Subscript>-K<Subscript>2</Subscript>CO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system

This experimental study of phase equilibria in the K₂SO₄-K₂CO₃-H₂O system at 385–500°C and pressures up to 100 MPa is directed to determine the sequence of phase transformations that generate heterogeneous supercritical fluids from the homogeneous one; the homogeneous supercritical region spreads into the ternary system from the K₂SO₄-H₂O subsystem. We found that heterogenization of supercritical fluid upon addition of K₂CO₃ starts with l₁=l₂ critical phenomena in solid saturated solutions and is attended by amalgamation of the stable immiscibility region that spreads from the K₂CO₃-H₂O system with the metastable immiscibility region that originates from the K₂SO₄-H₂O system. Our experimental results and the topological analysis of phase equilibria at temperatures above the critical point of water gave us the full scenario of the phase behavior of the title ternary system in the regions of fluid equilibria, g=l and l₁=l₂ critical phenomena, and liquid-liquid phase separation in two-, three-, and four-phase equilibria.     

Supramolecular 2D structure of [Co(2-Me-Pyz)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>4</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

The complex [Co(2-Me-Pyz)₂(H₂O)₄](NO₃)₂ is synthesized and its structure is determined. The crystals are monoclinic: space group P2₁/n, a = 10.685(2) Å, b = 6.837(1), c = 12.515(3) Å, β = 91.84(3)°, V = 913.8(3) ų, ρ_calcd = 1.042 g/cm ³, Z = 2. The Co²⁺ ion (in the inversion center) is coordinated at the vertices of the distorted octahedron by two nitrogen atoms of methylpyrazine and four oxygen atoms of the water molecules (Co(1)–N(1) 2.180(3), average Co(1)–O(w) 2.079(3) Å, angles at the Co atom 87.9(1)–92.1(1)°). Supramolecular pseudometallocycles are formed in the structure through the O(w)–H…N(1) hydrogen bonds between the coordinated H₂O molecules and the terminal nitrogen atoms of the 2-methylpyrazine molecules. Their interaction results in the formation of supramolecular layers joined by the NO₃ groups into a three-dimensional framework.