Thermodynamic properties of lithium chloride ammonia complexes for application inahigh-lifthigh temperature chemical heat pump

Ammonia absorption by and desorption from lithium chloride at different pressures has been studied using high-pressure differential scanning calorimetry, for application in a high-lift high temperature chemical heat pump. The measurements were performed under isobaric as well as under isothermal circumstances. Clausius–Clapeyron plots were constructed and used to calculate the thermodynamic parameters and to determine the stability regions of the different complexes. Controversies in literature as to the real existing phases are resolved.     

Extraction-spectrophotometric study on the vanadium(V)-2,3-dihydroxynaphthalene — iodonitrotetrazolium chloride — water — chloroform system and its analytical application

The formation of a new ternary ion-associate complex of vanadium(V) with 2,3-dihydroxynaphthalene and iodonitrotetrazolium chloride with a composition ratio of 1:2:1 is reported. The complex is quantitatively extracted from water into chloroform. The molar absorptivity (ɛ) of the extract at λ _max=340 nm is 2.5 × 10⁴ dm³/mol cm, and Beer’s law is obeyed for concentrations ranging from 0.1 to 0.9 μg/cm³ V(V). The following constants are determined: the extraction constant, the association constant, the distribution constant, and the recovery factor. The effects of foreign ions and reagents are studied. A selective and sensitive method is developed for determination of vanadium in steels.     

Hygrometric Determination of Water Activities and Osmotic and Activity Coefficients of NH4Cl–LiCl–H2O at 25°C

The mixed aqueous electrolyte system of ammonium and lithium chlorides has been studied by the hygrometric method at 25°C. The relative humidities of this system are measured at total molalities from 0.3 to 6 mol-kg^{– 1} for different ionic-strength fractions y of NH₄Cl with y = 0.33, 0.50, and 0.67. The data obtained allow the deduction of new water activities and osmotic coefficients. The experimental results are compared with the predictions of the ECA (extended composed additivity) law proposed in our previous work. The Zdanovskii–Stokes–Robinson (ZSR), the Robinson–Stokes (RS), Reilly–Wood–Robinson (RWR), the Pitzer, and the Lietzke–Stoughton (LS II) models are also compared with our results. Predictions made using these models are, in general, consistent with our results. From these measurements, new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions.     

An efficient procedure for the synthesis of coumarin derivatives using TiCl4 as catalyst under solvent-free conditions

The ability of titanium(IV) chloride as a catalyst to promote the Pechmann condensation reaction with a range of phenols and β-keto esters is described.The reaction was carried out by addition of TiCl₄ to a mixture of the phenol and the β-keto ester with thorough stirring in the absence of a solvent and represents an improvement on the classical Pechmann conditions. The yields of coumarins obtained via this novel protocol were significantly higher than those using the conventional method and the reaction duration was reduced to a few minutes or even a few seconds.     

Fourth-derivative spectrophotometric determination of neodymium in mixed rare earths with methyl thymol blue and cetylpyridinium chloride

A sensitive and selective method is described for the determination of neodymium in mixed rare earths using fourth-derivative spectrophotometry. The method is based on the absorption spectra of 4f electron transitions of the complex of neodymium with methyl thymol blue and cetylpyridinium chloride. The influence of various instrumental parameters and reaction conditions for maximum colour development are investigated. The calibration curve is linear over the range 0–3.5 g ml^–1 neodymium. The relative standard deviation for determination of 1.4 g ml^–1 neodymium (n = 7) is 1.6%. The detection limit (signal-to-noise ratio = 3) is 0.2 g ml^–1.     

The ordered phase of methylammonium lead chloride CH3ND3PbCl3

The perovskite-structured compound methylammonium lead chloride orders into a low-temperature phase of space group Pnma, in which at 80 K each of the orthorhombic axes , and is doubled with respect to the room temperature disordered cubic phase (). The structure was solved by ab initio methods using the programs EXPO and FOX. This unusual cell basis for space group Pnma is not that of a standard tilt system. This phase, in which the methylammonium ions, are ordered shows distorted octahedra. The octahedra possess a bond angle variance of 60.663°² and a quadratic elongation of 1.018, and are more distorted than those in the ordered phase of methylammonium lead bromide. There is also an alternating long and short Pb-Cl bond along a, due to an off-center displacement of Pb within the octahedron. This suggests that the most rigid unit is actually the methylammonium cation, rather than the PbCl₆ octahedra, in agreement with existing spectroscopic data.     

氯化钙/水-醇溶液稀释热

电解质溶液稀释热是溶液的重要热性质之一．由它可计算不同浓度下电解质的溶解热、表现相对摩尔焓、溶液中反应热和化合物生成热等．在电解质溶液理论研究中，稀释热也是重要的基础数据．由稀释热可推算溶液中组分的活度系数、渗透系数、相对偏摩尔焓及表观摩尔热容等[1-3]．在化工生产中，稀释热是化工过程能量计算不可缺少的数据．电解质水溶液稀释热已有不少研究[2，4]．但电解质混合溶剂体系稀释热报导甚少．随着加盐精馏技术、海水淡化技术等研究的进展，急需这方面数据．本文作者已报告了CaCl2／C2H5OH－H2O体系[5]和CaCl2／n－C…     

高阻隔材料——偏氯乙烯悬浮共聚树脂

本文介绍偏氯乙烯悬浮共聚树脂的优异阻隔性能、合成配方与工艺。     

Formation and Structure of [Al_(13)(μ_3-OH)_6(μ_2-OH)_6(μ_2-OH)_(12)(H_2O)_(24)]Cl_(15)·13H_2O

1 INTRODUCTION At present, the polyaluminium compounds are mainly studied by single-crystal X-ray diffraction method to obtain the components, structures and exis- tence forms of aluminium in hydrolysis system, and then hydrolysis courses and mechanisms of each hydrolytic polyaluminium cation could be further dis- closed[1～5]. Generally, the single crystals suitable for X-ray diffraction are obtained from the crystallization of polyaluminium cations into sulfates or selenates. Following …     

New Hexazirconium Clusters Containing Hydrogen Atoms

Reduction of ZrBr₄ with HSnBu₃ yielded a blue solid. When this blue solid was treated with PMe₃, a hexanuelear cluster [Zr₆Br₁₄H₄( PMe₃)₄] (2) was isolated. Reaction of the blue solid with [PPh₄]Br in CH₂Cl₂ resulted in the formation of a paramagnetic and unstable cluster anion, [Zr₆Br₁₈H₅]^2– (3), which disproportionated to form a new cluster anion, [Zr₆Br₁₈H₅]^3– (4) and some Zr(IV) species. Compounds containing 4 can also be obtained from reaction of the blue solid with Br^– in MeCN. Reduction of ZrCl₄ with HsnBu₃ gave a red–brown solid, and [Zr₆Cl₁₄H₄(AsMe₃)₄] (9) and [Zr₅Cl₁₂H₄(AsMe₃)₅](8) were obtained by reaction of the red–brown solid with AsMe₃. No cluster compounds containing amine ligands were obtained in the reaction of the red–brown solid with amines; only compounds containing the [Zr₆Cl₁₈ H₅]^3– anion and ammonium cations were isolated. Altogether ten products were characterized by single crystal X-ray diffraction and where possible, by ¹H NMR studies.