High temperature crystallization of aluminum fluoride. Course,hydrolysis, solid phases.

A study for AlF₃ crystallization from water solution was performed in the temperature range 100 to 200°C.Four solid phases were found to be precipitated, AlF₃.3H₂O (up to ca.120°C, cubic α-AlF₃.H₂O (decomposition of AlF₃.3H₂O in suspension), hexagonal β -AlF₃.H₂O (direct from solution) and the hydroxyfluoride Al(OH,F)₃.H₂O with an F/Al ratio of ca. 2.5 (hydrolysis of AlF₃). The extent of hydrolysis was established as a function of the initial AlF₃ concentration.X-ray diffraction and thermogravimetric data for the monohydrates were given and differences between the two indicated.     

Zum thermischen Verhalten von Aluminiumfluoridhydroxidhydrat AlF2,3(OH)0,7(H2O)

The Thermal Behaviour of Aluminium Fluoridehydroxide Hydrate AlF_2.3(OH)_0.7(H₂O) The thermal decomposition of AlF_2,3(OH)_0,7(H₂O) depends strongly on the partial pressure of the gaseous reaction products and proceeds in three overlapping steps, namely dehydratation, formation of x-ray amorphous Al₂O₃ and metastable β-AlF₃, and formation of α-AlF₃ and α-Al₂O₃. Beside that an exchange of F/OH takes place. The vaporization is mainly determined by the crucible type and pressure conditions, as shown by simultaneous TG-MS measurements too. Main gaseous species are H₂O and HF. The gas complexes HAlF₄, and H₂AlF₅ are observed.     

The reaction of aluminum fluoride solution with cryolite

The title reaction was investigated kinetically and the products obtained were analyzed and examined by physicochemical methods. The reaction was found to result in the formation of NaAlF₄.H₂O and its solid solutions with aluminum fluoride with compositions down to Na_0.5AlF_3.5.1.3H₂O, except in the presence of chiolite seed crystals, which cause the reaction to give it as the final product.It was suggested that the solid solution are brought about by coprecipitation of approximately monohydrated hexagonal ° -AlF₃ direct from solution, both compounds being presumably isostructural each other.Differences in the infrared spectra of Na₂AlF₆, Na₅Al₃F₁₄ and NaAlF₄.H₂O were indicated.Homogenous mixtures of Na₃AlF₆ and NaAlF₄.H₂O are found to react exothermally at 350°C to give Na₅Al₃F₁₄, while NaAlF₄.H₂O alone decomposes into Na₅Al₃F₁₄ and AlF₃.     

Kinetic and thermodynamic studies of MgHPO<Subscript>4</Subscript> · 3H<Subscript>2</Subscript>O by non-isothermal decomposition data

The thermal decomposition of magnesium hydrogen phosphate trihydrate MgHPO₄ · 3H₂O was investigated in air atmosphere using TG-DTG-DTA. MgHPO₄ · 3H₂O decomposes in a single step and its final decomposition product (Mg₂P₂O₇) was obtained. The activation energies of the decomposition step of MgHPO₄ · 3H₂O were calculated through the isoconversional methods of the Ozawa, Kissinger–Akahira–Sunose (KAS) and Iterative equation, and the possible conversion function has been estimated through the Coats and Redfern integral equation. The activation energies calculated for the decomposition reaction by different techniques and methods were found to be consistent. The better kinetic model of the decomposition reaction for MgHPO₄ · 3H₂O is the F _1/3 model as a simple n-order reaction of “chemical process or mechanism no-invoking equation”. The thermodynamic functions (ΔH*, ΔG* and ΔS*) of the decomposition reaction are calculated by the activated complex theory and indicate that the process is non-spontaneous without connecting with the introduction of heat.     

相变储能化合物CH3COONa·3H2O的热分解行为

通过对CH₃COONa·3H₂O进行热重(TG)及差示扫描量热法(DSC)测试,分析了其热分解行为,并从热力学的角度对其脱水过程进行了讨论。结果表明,CH₃COONa·3H₂O的脱水过程可分为两个阶段,先失液态水形成CH₃COONa溶液,再从溶液中脱出气态水,并且在加热过程中一直伴随着结晶水的蒸发逸出。用硅油覆盖的方法能很好地抑制低温时由于蒸汽压差异引起的CH₃COONa·3H₂O结晶水的不断蒸发逸出问题。     

X-ray study of tetrabutylammonium hydroxide trihydrate

Conclusions The crystal lattice parameters were determined for [(C₄H₉)₄N]OH · 3H₂O. Tetrabutylammonium hydroxide trihydrate crystallizes in the rhombic system with the parametersa=13.96, b=11.20, and c=10.50 Å.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2103–2104, September, 1976.     

An Eclipsed C(sp3)-CH3 Bond in a Crystalline Hydrated Tricyclic Orthoamide: Evidence for C?H…︁O hydrogen bonds

Accurate, low-temperature (81 K) X-ray analyses have been made for two crystalline modifications of the tricyclic orthoamide 1b : a cubic trihydrate in space group Pa3 (Z = 8), where the molecule has crystallographic threefold rotation symmetry, and an anhydrous monoclinic form in space group P2₁/c (Z = 8) where two symmetry-independent molecules have different configurations, one ail-trans. (as in the cubic trihydrate), the other cis, cis, trans. In the cubic trihydrate, each orthoamide molecule is attached to a triad of H₂o molecules by OH…?N H-bonds. A remarkable feature of this structure is the nearly eclipsed conformation about the central C-CH₃ bond. In the anhydrous crystal, both types of molecule have the normal staggered orientation of their Me groups. The reversal of the Me orientation in the trihydrate is attributed to C? H…?O H-bonding, which must be much stronger and more directionally specific than has been previously assumed.     

Strukturen und thermische Zersetzung von enH2(H3O)[AlF6] und enH2[AlF5(H2O)]

Structures and Thermal Decomposition of enH₂(H₃O)[AlF₆] and enH₂[AlF₅(H₂O)] By precipitation with ethylene diamine (en) from a hydrofluoric acid solution of aluminium enH₂(H₃O)[AlF₆] is formed. It crystallizes in the orthorhombic space group Pnma, a = 1084.9(1), b = 1079.4(1), c = 682.0(1) pm, R = 0.032. H₃O⁺ cations and [AlF₆]^3– anions are connected via strong H bonds to layers which are further linked to a 3 D network by H bonds from the enH₂²⁺ cations. By recrystallization from water or precipitation from a less acid solution enH₂[AlF₅(H₂O)] is formed, which crystallizes monoclinic in the space group P2₁ (a = 660.0(1), b = 563.5(1), c = 994.4(2) pm, β = 98.44(3)°, R = 0.029). The [AlF₅(H₂O)]^2– anions are linked by strong O–H…F bonding to form ‘einer-double chains' interconnected again via the enH₂²⁺ cations to a 3 D framework. Thermoanalytical investigations show that enH₂[AlF₅(H₂O)], by loss of water above 150 °C, as well as enH₂(H₃O)[AlF₆], by loss of water and HF above 120 °C, transform to enH₂AlF₅. The subsequent decomposition goes over NH₄⁺ containing intermediates towards β-AlF₃. Before decomposition the oxonium fluoroaluminate reveals a reversible phase transition at 99 °C.     

Desorption Behaviour of HF,HCFC-133a and HFC-134a on a Catalyst Supported on γ-AlF3

The desorption behaviour (desorption temperature and extent of desorption) of HF,HCFC-133a (CF₃CH₂Cl) and HFC-134a (CF₃CH₂F) on γ-AlF₃ or catalyst supported on γ-AlF₃ was studied using an adsorption apparatus and TG, DTA and DSC methods. On the basis of the results a reaction mechanism was proposed for the preparation of HFC-134a. The γ-AlF₃ employed for preparing the catalyst was expected to be stable below 550°C based on the crystalline phase transition temperature of γ-AlF₃. This revised version was published online in August 2006 with corrections to the Cover Date.     

Zinc Hydrogen Ortho Arsenate Trihydrate,ZnHAsO4 · 3 H2O

Zinc hydrogen ortho arsenate trihydrate, ZnHAsO₄ · 3 H₂O has been studied by static isothermal dehydration, X-ray powder diffraction, and infra-red absorption spectral techniques. The results of these studies clearly indicate that the compound is to be formulated as zinc hydroxide dihydrogen ortho arsenate dihydrate, Zn(OH)(H₂ASO₄) · 2 H₂O.     

Isomerisation of ω-alkenyl substituted cyclohexane-1,3-dione enol derivatives using rhodium catalysis. A practical synthesis of substituted resorcinols

Treatment of the ω-alkenyl substituted cyclohexane-1,3-dione enol derivatives (1), (11), and (13) with rhodium trichloride trihydrate leads to the corresponding resorcinol derivatives (2), (12), and (15) respectively. By contrast, the RhCl₃.3H₂O catalysed isomerisations of the related enol ethers (5) and (9) instead produce the dienones (6) and (10) respectively.     

A new hydrate of magnesium carbonate,MgCO3·6H2O

During investigations of the formation of hydrated magnesium carbonates, a sample of the previously unknown magnesium carbonate hexahydrate (MgCO₃·6H₂O) was synthesized in an aqueous solution at 273.15 K. The crystal structure consists of edge‐linked isolated pairs of Mg(CO₃)(H₂O)₄ octahedra and noncoordinating water molecules, and exhibits similarities to NiCO₃·5.5H₂O (hellyerite). The recorded X‐ray diffraction pattern and the Raman spectra confirmed the formation of a new phase and its transformation to magnesium carbonate trihydrate (MgCO₃·3H₂O) at room temperature.     

NMR and Raman spectral studies of ammonium hydrogen selenites single crystals

The chemical composition and peculiarities of the structure of a salt that precipitates from aqueous solution of NH₄HSeO₃ at the 25 °C was studied by NMR and Raman spectroscopy methods using the single crystal samples with different heavy water contents. It was proved that this salt is actually monohydrate of hydrogen selenite, NH₄HSeO₃H₂O but not trihydrate of pyroselenite, (NH₄)₂Se₂O₅3H₂O as was assumed previously based on the data cited in the literature.     

A square‐planar hydrated cationic tetrakis(methimazole)gold(III) complex

The cationic pseudo‐square‐planar complex tetrakis(1‐methyl‐2,3‐dihydro‐1H‐imidazole‐2‐thione‐κS)gold(III) trichloride sesquihydrate, [Au(C₄H₆N₂S)₄]Cl₃·1.5H₂O, was isolated as dark‐red crystals from the reaction of chloroauric acid trihydrate (HAuCl₄·3H₂O) with four equivalents of methimazole in methanol. The Au^III atoms reside at the corners of the unit cell on an inversion center and are bound by the S atoms of four methimazole ligands in a planar arrangement, with S—Au—S bond angles of approximately 90°.     

Lithium pertechnetate trihydrate LiTcO<Subscript>4</Subscript> · 3H<Subscript>2</Subscript>O: Synthesis and crystal structure

Lithium pertechnetate trihydrate was obtained and its crystal structure was examined; LiTcO₄ · 3H₂O crystallizes in hexagonal crystal system as colorless elongated prismatic crystals (space group P6₃/mc, Z = 2; at 100 K: a = 7.8604(1) Å, c = 5.4164(1) Å). This compound is isostructural with LiClO₄ · 3H₂O, LiBrO₄ · 3H₂O, and LiMnO₄ · 3H₂O.     

Comparative structural investigation of aluminium fluoride solvates

To get some insight by conclusions of analogy into the drying process of alcoholic aluminium fluoride sol–gels [AlF₃/(ROH)_x], the structures of α- and β-AlF₃3H₂O as well as of the nonahydrate AlF₃9H₂O are reinvestigated and discussed based on X-ray single crystal structural data. In addition, neutron diffraction experiments of the latter allowed the refinement of proton positions. In accordance with crystal structures, low-temperature solid state ²⁷Al-, ¹H- and ¹⁹F-MAS NMR spectra convincingly confirm the structural similarity between α-AlF₃3H₂O and AlF₃9H₂O, while the β-phase material is structurally different forming chain structures. Thermal analysis of AlF₃/(ROH)_x gave evidence for discrete AlF₃:ROH ratios of only 1:0.45 and 1:0.1, and solution NMR showed some similarities between aqueous and alcoholic systems.     

Hydrate schwacher und starker Basen. VII. Zum System Caesiumhydroxid-Wasser: Die Kristallstrukturen von CsOH · 2H2O und CsOH · 3H2O

Hydrates of Weak and Strong Bases. VII. Concerning the System Cesium Hydroxide—Water: The Crystal Structures of CsOH · 2H₂O and CsOH · 3H₂O In the context of structural studies of hydrates of the alkali metal hydroxide the crystal structure of CsOH · 2H₂O and CsOH · 3H₂O have been determined for the first time. The diffractometer data, obtained at -150 · C,made it possible to locate and refine also all the H-atoms. The dihydrate was found to probably form only one phase, melting incongruently at 2,5 · C. It is orthorhombic with space group Pca2₁ and Z = 8 formula units per unit cell. The lattice constants are a = 13.238, b = 6.747 and c = 9.121 A. With 1870 independent observed reflection a final R value of 0.013 was obtained. The trihydrate, melting congruently et -5.5 ·C, is monoclinic with space group P2₁/n,Z = 4 and lattice constants a = 8.637, b = 5.984, c = 10.061 Å and ß = 96.57 ·. With 2098 independent observed reflection the final R is 0.026. In both hydrate structures there are no simple characteristic coordination polyhedra for the cations; in each case it is rather the hydrogen-bonded and fully ordered anionic water structure which shows up as the determining building principle. Both these water structures are altogether three-dimensional, but primarily contain layers. The anionic layers are formed by condensation of small and medium rings, namely four-, five- and seven-membered rings in CsOH · 2H₂O and four-, five- and six membered ones in CsOH · 3H₂O. They are linked together by one set each of extra H₂O molecules between the layers as well as by the Cs⁺ ions.     

Synthetic ferric sulfate trihydrate,Fe2(SO4)3·3H2O,a new ferric sulfate salt

Ferric sulfate trihydrate has been synthesized at 403 K under hydrothermal conditions. The structure consists of quadruple chains of [Fe₂(SO₄)₃(H₂O)₃] parallel to [010]. Each quadruple chain is composed of equal proportions of FeO₄(H₂O)₂ octahedra and FeO₅(H₂O) octahedra sharing corners with SO₄ tetrahedra. The chains are joined to each other by hydrogen bonds. This compound is a new hydration state of Fe₂(SO₄)₃·nH₂O; minerals with n = 0, 5, 7.25–7.75, 9 and 11 are found in nature.     

Preparation,Thermal Behaviour,and Crystal Structure of MgAl<Subscript>2</Subscript>F<Subscript>8</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>

Summary.  Single crystals of MgAl₂F₈(H₂O)₂ have been obtained under hydrothermal conditions (250°C, 14 d) from a starting mixture of AlF₃ and MgAlF₅(H₂O)₂ in a 5% (w/w) HF solution. The crystal structure has been determined and refined from single crystal data (Fmmm (#69), Z = 4, a = 7.2691(7), b = 7.0954(16), c = 12.452(2) ?, 281 structure factors, 27 parameters, R(F ² > 2σ (F ²)) = 0.0282, wR(F ² all) = 0.0885). The obtained crystals were systematically twinned according to (010/100/001) as twinning matrix, reflecting the pseudo-tetragonal metric. The crystal structure is composed of perowskite-type layers built of corner sharing AlF₆ octahedra with an overall composition of AlF₄ ⁻ which are connected via common fluorine atoms of [MgF_4/2(H₂O)_2/1] octahedra. Group-subgroup relations of MgAl₂F₈(H₂O)₂ to WO₃(H₂O)_0.33 and to other M(II)M(III)₂ F₈(H₂O)₂ structures are briefly discussed. Above 570°C, MgAl₂F₈(H₂O)₂ decomposes under elimination of water into α-AlF₃, β-AlF₃, and MgF₂. Received October 29, 2001. Accepted (revised) December 6, 2001     

硫化铜空心球的合成和生长机理及其在抗肿瘤中的应用

以Cu(NO_3)_2·3H_2O,H_2C_2O_4和Na_2S·9H_2O为原料,利用简易水热方法合成了笼状硫化铜空心球。所得产物用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)进行了表征,并研究了其可能的形成机理。所得CuS空心球具有较高的光热转换性能,在近红外光辐照下,对肿瘤细胞具有明显的光热毒性。