Li+，Na+//CO32-，B4O72--H2O交互四元体系273 K介稳相平衡研究

我国青藏高原由于特殊的地理气候特点而盐湖众多,西藏境内的扎布耶盐湖卤水中锂、硼、钾浓度之高,在世界盐湖中也非常罕见[1-3].     

五元体系Li+，Na+//CO32-，SO42-，B4O72--H2O 288 K介稳相平衡研究

采用等温蒸发法研究五元体系Li⁺,Na⁺//CO₃^2-,SO₄^2-,B₄O₇^2--H₂O 288 K介稳相平衡关系,测定在288 K条件下的介稳平衡溶液中各组分的溶解度和溶液密度,根据实验数据绘制相应的介稳平衡相图及密度组成图。研究结果表明该五元体系介稳相平衡中有复盐Na₃Li(SO₄)₂·6H₂O生成,其介稳相图中有4个共饱点,9条单变量曲线,6个Li₂CO₃饱和的结晶区分别为LiBO₂·8H₂O,Na₂B₄O₇·10H₂O,Na₂CO₃·10H₂O,Na₂SO₄,Li₂SO₄·H₂O和复盐Na₃Li(SO₄)₂·6H₂O。     

Li+，Na+//SO42-，B4O72--H2O交互四元体系288 K介稳相平衡研究

采用等温蒸发法研究了四元体系Li⁺，Na⁺//SO₄^2-，B₄O₇^2--H₂O 288 K介稳相平衡及平衡液相物化性质(密度、电导率、折光率、粘度和pH值)，测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质。根据实验数据绘制了相应的介稳相图及物化性质组成图。研究发现：该体系介稳平衡中有复盐Li₂SO₄·Na₂SO₄形成。其介稳相图中有3个共饱和点，7条单变量曲线，平衡固相为：Li₂SO₄·H₂O，Na₂SO₄，Li₂SO₄·Na₂SO₄，Li₂B₄O₇·3H₂O，Na₂B₄O₇·10H₂O。复盐Li₂SO₄·Na₂SO₄和一水硫酸锂(Li₂SO₄·H₂O)有较小的结晶区，而Li₂B₄O₇·3H₂O和Na₂B₄O₇·10H₂O有较大的结晶区；该四元体系介稳平衡条件下未发现Na₂SO₄·10H₂O的结晶区。     

四元体系Na+,K+∥CO32-,B4O72--H2O 298K相平衡研究

采用等温溶解平衡法研究了四元体系Na^ ,D^ //CO3^2-,B4O7^2--H2O 298K时的相关系,该四元体系298K时的溶解度等温图含有5个相区：Na2B4O7.10H2O,K2B4O7.4H2O,Na2CO3.10H2O,K2CO3.3/2H2O和复盐Na2CO3.K2CO3.H2O,7条单变量曲线和3个共饱点,其中NaCO3.K2CO3.H2O K2CO3.3/2H2O K2B4O7.4H2O为相称共饱点,体系中发现了一种新的复盐：Na2CO3.K2CO3.H2O,这种复盐同时存在于含Na^ ,K^ //CO3^2-H2O三元体系的其它四元或高元体系中。     

五元体系Li＋, K＋//, CO32- ,SO42- , B4O72- -H2O在288 K时的介稳相平衡研究

采用等温蒸发法研究了五元体系Li^＋, K^＋//, , -H₂O 在288 K时的介稳相平衡关系, 测定了该五元体系在288 K条件下的介稳平衡的溶解度和溶液密度, 根据实验数据绘制了相应的介稳平衡相图和水图. 相平衡研究结果表明该五元体系介稳相平衡中有复盐K₂SO₄•Li₂SO₄生成, 其介稳相图(Li₂CO₃饱和)有4个共饱和点, 9条单变量曲线, 6个Li₂CO₃饱和的结晶区分别为LiBO₂•8H₂O, K₂B₄O₇•4H₂O, K₂CO₃•3/2H₂O, K₂SO₄, Li₂SO₄•H₂O和复盐 K₂SO₄•Li₂SO₄.     

五元交互体系Li+,Na+,K+//CO32-,Cl--H2O在298.15K的相平衡研究

针对西藏扎布耶盐湖卤水组成,采用等温溶解平衡法研究了五元交互体系Li+,Na+,K+//CO32-,Cl--H2O于298.15K时的相平衡,并绘制了相图(空间立体图和Li2CO3饱和的投影图).结果表明,该五元体系相图含有7个结晶区、13条单变量线和4个无变量点.7个结晶区由6个单盐结晶区和1个复盐结晶区组成,分别为LiCl·H2O,NaCl,KCl,Li2CO3,K2CO3·3/2H2O,Na2CO3·10H2O和NaKCO3·6H2O,没有形成固溶体和天然碱(Na2CO3·NaHCO3·2H2O).4个无变量点标记成K1,K2,K3和K4,所对应的平衡固相盐分别是:Li2CO3+NaKCO3·6H2O+Na2CO3·10H2O+KCl,Li2CO3+NaKCO3·6H2O+K2CO3·3/2H2O+KCl,Li2CO3+NaCl+KCl+LiCl·H2O和Li2CO3+NaCl+Na2CO3·10H2O+KCl.     

五元体系Li+/Cl-，CO32-，SO42-，B4O72--H2O 298 K相关系实验研究

Zabuye saline lake, Tibet, China, is unrivalled in the world for its high concentration of chloride, sulfate, carbonate and borate of lithium, sodium and potassium. Always at the later stage of the evaporation of brines, most sodium and potassium salts are crystallized out, so the main components of brines can be described with the Li⁺, Mg²⁺/Cl^-, SO₄^2-, CO₃^2-, B₄O₇^2--H₂O system. As a part of study on the equilibrium of this complex system, the equilibrium solubilities and phase diagram of the quinary system Li⁺/Cl^-，CO₃^2-，SO₄^2-，B₄O₇^2--H₂O at 298 K were studied by isothermal dissolution equilibrium method. In the 3-dimentional solubility diagram or its projection diagram saturated with solid LiCl, there are four crystallization fields, four univariant curves and one invariant point. At the invariant point, the saturated solid salts are LiCl·H₂O, Li₂B₄O₇·3H₂O, Li₂CO₃and Li₂SO₄·H₂O. No double salt or solid solution is formed.     

Li＋, Na＋//SO42－, CO32－-H2O交互四元体系288 K介稳相平衡研究

采用等温蒸发法研究了四元体系Li^＋, Na^＋// SO₄^2－, CO₃^2－-H₂O 288 K介稳相平衡及平衡液相的密度、电导率、折光率、粘度和pH值, 测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质. 根据实验数据绘制了相应的介稳相图. 研究发现: 该体系介稳平衡中有复盐Na₃Li(SO₄)₂•6H₂O形成. 其介稳相图中有3个共饱点, 7条单变量曲线, 平衡固相为: Li₂SO₄•H₂O, Na₂SO₄, Na₃Li(SO₄)₂•6H₂O, Li₂CO₃, Na₂CO₃•10H₂O. 复盐Na₃Li(SO₄)₂•6H₂O和一水硫酸锂(Li₂SO₄•H₂O)的结晶区较小, 而Li₂CO₃的结晶区最大; 该四元体系介稳平衡条件下未发现Na₂SO₄•10H₂O的结晶区.     

Li＋, Na＋//SO42－, CO32－-H2O交互四元体系288 K介稳相平衡研究

采用等温蒸发法研究了四元体系Li^＋, Na^＋// SO₄^2－, CO₃^2－-H₂O 288 K介稳相平衡及平衡液相的密度、电导率、折光率、粘度和pH值, 测定了该四元体系288 K条件下介稳平衡溶液溶解度及物化性质. 根据实验数据绘制了相应的介稳相图. 研究发现: 该体系介稳平衡中有复盐Na₃Li(SO₄)₂•6H₂O形成. 其介稳相图中有3个共饱点, 7条单变量曲线, 平衡固相为: Li₂SO₄•H₂O, Na₂SO₄, Na₃Li(SO₄)₂•6H₂O, Li₂CO₃, Na₂CO₃•10H₂O. 复盐Na₃Li(SO₄)₂•6H₂O和一水硫酸锂(Li₂SO₄•H₂O)的结晶区较小, 而Li₂CO₃的结晶区最大; 该四元体系介稳平衡条件下未发现Na₂SO₄•10H₂O的结晶区.     

Na+，K+//Br-，SO42--H2O四元体系323 K相平衡研究

采用等温溶解平衡法研究了四元体系Na⁺,K⁺//Br^-,SO₄^2--H₂O在323 K的相平衡关系,测定了该体系323 K的溶解度及平衡液相的密度,绘制了该体系的相图。研究发现：平衡体系存在复盐钾芒硝Na₂SO₄·3K₂SO₄的结晶区。其相图由3个共饱和点,7条单变量曲线和5个结晶区组成。相区分别对应NaBr·2H₂O、Na₂SO₄、K₂SO₄、KBr和Na₂SO₄·3K₂SO₄结晶区。其中复盐钾芒硝Na₂SO₄·3K₂SO₄,Na₂SO₄和K₂SO₄有较大结晶区,而NaBr·2H₂O和KBr有较小结晶区。对比了等温条件下四元体系Na⁺,K⁺//Cl^-,SO₄^2--H₂O相平衡结果。实验结果表明溴化物对硫酸盐有较强盐析作用。     

Metastable phase equilibria in the systems K2SO4 + K2B4O7 + H2O and KCl + K2B4O7 + H2O at 308.15 K

Experimental studies on the metastable solubilities and physicochemical properties (density and refractive index) in the ternary systems K₂SO₄ + K₂B₄O₇ + H₂O and KCl + K₂B₄O₇ + H₂O at 308.15 K were determined with the method of isothermal evaporation. According to the experimental results, the phase diagrams of the two ternary systems were plotted. In the phase diagrams, there are both two isotherm evaporation curves, one eutectic point corresponding to K₂SO₄ + K₂B₄O₇ · 4H₂O, and KCl + K₂B₄O₇ · 4H₂O, respectively. Both of the ternary systems belong to a simple eutectic type, and neither double salts nor solid solutions formed in the ternary systems. A comparison of the stable and metastable phase diagrams of the ternary systems K₂SO₄ + K₂B₄O₇ + H₂O and KCl + K₂B₄O₇ + H₂O shows that the supersaturated phenomenon of potassium borate tetrahydrate is significant and easier to appear the metastable behavior.     

Zum System K2O/PbO. Zur Kenntnis von K2Pb2O3

On the System K₂O/PbO: The Crystal Structure of K₂Pb₂O₃ Orange-coloured single crystals of K₂Pb₂O₃ crystallize by means of 4-circle-Diffractometer data (237 of 238 possible hkl, R = 5.9₉%, MoKα) cubic with a = 8.41₉ Å, Z = 4, in space group I2₁3?T⁵, parameter see text. We find a superstructure of the perovskite type of structure, where, concerning the formula KPbO_3/2, half of the O^2? ions are omitted systematically, without loosing the 3-Dimensional arrangement of order. Pb²⁺ is surrounded by 3 K⁺ by 6 O^2? and O^2? by 2 Pb²⁺ and 4 K⁺. The Madelung Part of the Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, are calculated and discussed.     

K and mixed K+O adlayers on Rh(110)

The evolution of the structure of the adlayers and the substrate during adsorption of K and coadsorption of K and O on Rh(110) is studied by scanning tunneling microscopy and low-energy electron diffraction. The K adsorption at temperature above 450 K leads to consecutive (1x4), (1x3), and (1x2) missing-row reconstructions for coverage up to 0.12 ML, which revert back to (1x3) and (1x4) with increasing coverage up to 0.21 ML. The coadsorption of different oxygen amount at T>450 K and eventually following reduction-reoxidation cycles led to a wealth of coadsorbate structures, all involving substrate missing-row-type reconstructions, some including segmentation of Rh rows along the [110] direction. The presence of K stabilizes the (1x2) missing-row reconstruction, which facilitates the formation of a great variety of very open (10x2)-type reconstructions at high oxygen coverage, not observed in the single adsorbate systems.     

K2TiSi3O9·H2O

Single crystals of dipotassium titanium trisilicate hydrate were synthesized and the crystal structure was refined using data from single‐crystal X‐ray diffraction. The structure is a three‐dimensional mixed framework and contains channels formed by six‐ and eight‐membered rings. K⁺ ions and water mol­ecules are located in the channels.     

Structural and Raman Spectroscopic Investigations of K4BaSi3O9 and K4CaSi3O9

The crystal structures of K₄BaSi₃O₉ and K₄CaSi₃O₉ have been characterized by X‐ray diffraction techniques as well as Raman spectroscopy. The structure of K₄CaSi₃O₉ has been refined from powder diffraction data via the Rietveld method using polycrystalline material prepared from solid state reactions. The compound is isostructural with form I of K₄SrSi₃O₉. It crystallizes with 16 formula units in a cubic primitive cell (a = 15.94014(3) Å, V = 4050.20(1) ų) and adopts space group . K₄CaSi₃O₉ belongs to the group of cyclosilicates and contains highly puckered twelve‐membered [Si₁₂O₃₆]‐rings centered on the . Five of the seven crystallographically independent alkaline and alkaline earth cations are surrounded by six oxygen ligands in the form of distorted octahedra, which share opposite triangular faces and form non‐intersecting columns parallel to the body diagonals of the cubic unit cell. This arrangement corresponds to one of the cubic cylinder or rod packings. The two remaining sites have more irregular coordination environments with eight next oxygen neighbors. High temperature X‐ray powder diffraction data have been collected to determine the thermal expansion of this material: between room temperature and 700 °C the coefficient of thermal expansion has a value of α = 12.9(2) × 10^?6 [°C^?1]. Single crystals of K₄BaSi₃O₉ have been obtained from the devitrification of a glass with the same composition. The structure was determined from a single crystal diffraction data set collected at ?100 °C and refined to a final R index of 0.0298 for 1288 observed reflections (I > 2σ(>I)). The compound is isostructural with modification II of K₄SrSi₃O₉. Basic crystallographic data are as follows: space group Ama2, a = 11.0695(15) Å, b = 8.0708(10) Å, c = 11.905(2) Å, V = 1063.6(3) ų, Z = 4. With respect to the silicate anions the material can be classified as a sechser single chain silicate. The crankshaft‐like chains run parallel to [100] and are linked by K and Ba cations, which are distributed among five crystallographically independent sites. The coordination polyhedra of two of the non‐tetrahedral cations can be described by distorted octahedra sharing opposite triangular faces. They build non‐intersecting columns parallel to [011] and [0‐11], respectively. The other sites exhibit more irregular coordination spheres with 7‐9 neighbours.     

Darstellung und kristallographische Daten von K2Si2O5, KHSi2O5I und K2Si4O9

K₂Si₂O₅ KHSi₂O₅I und K₂Si₄O₉ have, been synthesized partly by annealing and partly by hydrothermal treatment of glasses of suitable chemical composition. From powder and single crystal x-ray diagrams the lattice dimensions have been determined (see: ?Inhaltsübersicht”?).     

K6[Mn2O6] und K6[Fe2 O6] - ein Vergleich

K₆[Mn₂O₆] and K₆[Fe₂O₆] - a Comparison K₆[Mn₂O₆] has been prepared (dark-red single crystals). The structure (a = 8.88₆, b = 6.76₀, c = 11.39₄ Å, γ = 132.1°, space group P2₁, Z = 2, 1151 symmetry independent reflections hk0–hk9, R = 0.051) shows Al₂Cl₆-like anions [Mn₂O₆]^6?. By unit-cell transformation to the monoclinic setting P2₁/a (a = 6.76₀, b = 11.39₄, c = 6.63₈ Å, β = 96,9°) the structural similarity to K₆[Fe₂O₆] becomes evident. The Madelung Part of Lattice Energy, MAPLE, is calculated.     

Synthese der Phoracantholide K,O und M

Synthesis of Phoracantholide K, O and M Two 14membered ring lactones 3 and 4 and a 12membered ring lactone 5 isolated from the metasternal secretion of the eucalypt longicorn Phoracantha synonyma have been synthesized as racemic mixtures by the following method. Reaction of the dilithium derivative of 5-hexynoic acid (6) with threo-8-bromo-2,4-isopropylidenedioxyoctane (7) , followed by removal of the protecting group and esterification with diazomethane gave methyl-threo-11, 13-dihydroxy-5-tetradecy-noate (8) (s. Scheme 2). Partial hydrogenation of the triple bond in 8 with Lindlar Pd-catalyst, followed by saponification lead to (threo, Z)-11, 13-dihydroxy-5-tetra-decenoic acid (10) . The dihydroxy acid 10 was converted into the S-(2-pyridyl) thioate and cyclized in diluted benzene solution under the influence of silver ions to yield the corresponding 12- and 14-membered lactones in approximately equal amounts. Isomerization of the mixture with p-toluenesulfonic acid in methylene chloride yielded the 14-membered lactone (cis-11, 13–5Z)-11-hydroxy-5-tetradecen-13-olide almost exclusively. It proved to be identical in its properties with natural phoracantholide K (3). With 5-hexynoic acid and 7-tetrahydropyranyloxy-octyl bromide or 5-tetrahydropyranyloxy-hexyl bromide as starting materials (±)-phoracantholide O (4) and M (5) have been synthesized in an analogous manner.     

Verfeinerung der Kristallstruktur von K2O2

Refinement of the Crystal Structure of K₂O₂ The crystal structure of K₂O₂ has been refined using 241 diffractometer data (Cmca; a = 6.733(1), b = 6.996(1), c = 6.474(1) Å; Z = 4; R_w = 0.050). The distance O? O (1.541(6) Å) is significantly larger than that one assumed for alkali metal peroxides, so far.