Theoretical and Experimental Exploration of the Energy Landscape of the Quasi‐Binary Cesium Chloride/Lithium Chloride System

As a case study, the energy landscape of the cesium chloride/lithium chloride system was investigated by combining theoretical and experimental methods. Global optimization for many compositions of this quasi‐binary system gave candidates for possible modifications that constitute promising targets for subsequent syntheses based on solid‐state reactions. Owing to the synergetic and complementary nature of the computational and experimental approaches, a substantially better efficiency of exploration was achieved. Several new phases were found in this system, for the compositions CsLiCl₂ and CsLi₂Cl₃, and their thermodynamic ranking with respect to the already‐known phases was clarified. In particular, the new CsLiCl₂ modification was shown to be the low‐temperature phase, whilst the already‐known modification for this composition corresponded to a high‐temperature phase. Based on these results, an improved cesium chloride/lithium chloride phase diagram was derived, and this approach points the way to more rational and more efficient solid‐state synthesis.     

Investigation of new fluxes for the single-crystal growth of stoichiometric lithium niobate

Thermoanalytical and crystal growth investigations of the ternary system Cs₂O-Li₂O-Nb₂O₅ are presented in order to grow stoichiometric LiNbO₃ (LN) crystals. Part of the phase diagram is determined and subsolidus phases are identified at room temperature by X-ray powder diffraction. Among the constituent phases, a new tetragonal cesium lithium niobate phase is assessed. From the Cs₂O-Li₂O-Nb₂O₅ system, good quality quasi-stoichiometric LN crystals can be grown.     

Isobaric vapor–liquid equilibria for 1-propanol + water + lithium chloride at 100 kPa

Isobaric vapor–liquid equilibria for the ternary system 1-propanol+water+lithium chloride has been measured at 100 kPa using a recirculating still. The addition of lithium chloride to the solvent mixture produced an important salting-out effect over the alcohol and the azeotrope tended to be eliminated when the salt content increased, and two immiscible liquid phases were observed in a broad range of salt concentration. The experimental data sets were fitted with the electrolyte NRTL model and the parameters of Mock et al.’s model were estimated. This model has proved to be suitable to represent experimental data in the entire range of compositions. The effect of lithium chloride on the vapor–liquid equilibrium of the propanol+water system has been compared with that produced by other salts.     

Highly efficient separation of lithium chloride from seawater

A complexing reagent composed of two bipyridine moieties enabled the efficient separation of lithium chloride through liquid membrane from seawater, in which 0.005% lithium chloride is contained (more than 99% metal chlorides are NaCl, KCl, MgCl2, and CaCl2). That is, two separations by our liquid membrane changed the molar ratio of LiCl from 0.005% to 80%. The striking characteristic of this compound is that the lithium ion is separated efficiently from alkali and alkaline earth metal ions without the lipophilic anion. Thus this new membrane system contructed by us offers a low-energy, low-cost, and environmentally friendly method to enable the routine use of lithium chloride separation from seawater.     

Characterization of the high-pressure structural transition and thermodynamic properties in sodium chloride: a computational investigation on the basis of the density functional theory

Using first-principles calculations, the elastic constants, the thermodynamic properties, and the structural phase transition between the B1 (rocksalt) and the B2 (cesium chloride) phases of NaCl are investigated by means of the pseudopotential plane-waves method. The calculations are performed within the generalized gradient approximation to density functional theory with the Perdew-Burke-Ernzerhof exchange-correlation functional. On the basis of the third-order Birch-Murnaghan equation of states, the transition pressure Pt between the B1 phase and the B2 phase of NaCl is determined. The calculated values are generally speaking in good agreement with experiments and with similar theoretical calculations. From the theoretical calculations, the shear modulus, Young's modulus, rigidity modulus, and Poisson's ratio of NaCl are derived. According to the quasi-harmonic Debye model, we estimated the Debye temperature of NaCl from the average sound velocity. Moreover, the pressure derivatives of elastic constants, partial differentialC11/partial differentialP, partial differentialC12/partial differentialP, partial differentialC44/partial differentialP, partial differentialS11/partial differential P, partial differentialS12/partial differentialP, and partial differentialS44/partial differentialP, for NaCl crystal are investigated for the first time. This is a quantitative theoretical prediction of the elastic and thermodynamic properties of NaCl, and it still awaits experimental confirmation.     

2-Methyl-3-butyn-2-ol conversion on AlPO4-cesium oxide (20 wt.%) catalysts obtained by impregnation with cesium chloride

2-Methyl-3-butyn-2-ol underwent almost exclusively dehydration to 3-methyl-3-buten-1-yne (acid activity) on pure AlPO₄, whereas its modification with cesium oxide developed AlPO₄-based materials with increased basic properties and hence, high selectivities to the base-catalyzed cleavage of MBOH yielding acetone and acetylene. At the same conversion level, catalysts obtained from cesium chloride exhibit higher selectivities to the base-catalyzed process than those obtained from cesium acetate.     

New solvent for polyrotaxane. I. Dimethylacetamide/lithium chloride (DMAc/LiCl) system for modification of polyrotaxane

Dimethylacetamide (DMAc) containing 8–9% (w/w) of lithium chloride (LiCl) or lithium bromide (LiBr) was found to be a good solvent for a polyrotaxane consisting of poly (ethylene glycol) (PEG) and α‐cyclodextrin (CD). In the new DMAc/LiCl solvent system, various modification reactions such as acetylation, direct dansylation, and reaction with acid chloride could be performed, which was unattainable in the previously reported solvents, i.e., dimethylsulfoxide (DMSO) and aqueous sodium hydroxide solution. Acetylation with acetic anhydride and direct dansylation of the polyrotaxane were investigated in detail in comparison with reactions in DMSO. The dissolution of the polyrotaxane in DMAc/LiCl suggested that the solubility and insolubility of the polyrotaxane is strongly in relation to the inter‐ and intramolecular hydrogen bonding of the polyrotaxane. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 532–538, 2006     

Intermediate phases in the dodecyltrimethylammonium chloride/water system

Two intermediate phases have been found in the concentration range between the hexagonal and concentrated cubic phases in the binary system dodecyltrimethylammonium chloride (C₁₂TACl)/water. This region in the phase diagram was studied by means of ²H NMR of specifically deuteriated surfactant as well as by ¹⁴N NMR. Below 35°C, an intermediate phase with non-cylindrical aggregates is formed in the concentration range 80 to 84 wt% surfactant, X-ray data from this phase can be indexed to a centred rectangular lattice. In addition, there is a uniaxial phase with a reduced quadrupole splitting. The aggregates comprising the centred rectangular phase were analysed by means of bandshape analysis of the NMR spectra and by small angle X-ray scattering.     

Molecular conformational structures of 2-fluorobenzoyl chloride, 2-chlorobenzoyl chloride, and 2-bromobenzoyl chloride by gas electron diffraction and normal coordinate analysis aided by quantum chemical calculations

The gas phase molecular structures and conformational compositions of 2-fluorobenzoyl chloride, 2-chlorobenzoyl chloride, and 2-bromobenzoyl chloride have been investigated using gas electron diffraction data obtained from experiments performed in the laboratories of the University of Oslo and Oregon State University. The refinements on the experimental data have been aided by normal coordinate calculations as well as extensive ab initio molecular orbital and density functional theory calculations up to the levels of MP4(SDQ) and B3LYP with larger basis sets up to the level of 6-311 + G(2d,p) for the computed molecular geometries, electronic energies, vibrational zero-point energies and entropy corrections, gas mixture conformational compositions, and MP2(fc) quantum mechanical force fields. The three title molecules each exist in the gas phase as two stable non-planar conformers anti and gauche with respect to the halogen atom positions with anti the lower energy conformer in each case. Among the three title molecules there have been found considerable experimental and theoretical support for several trends in molecular or conformational behavior with increasing ortho halogen atomic size: An increasing although disputable trend in the C=O bond distance values; an increasing trend in the average phenyl ring C–C bond distance values; an increasing trend in the contribution of the gauche conformer to the gaseous mixture lowering the standard free energy difference values (ΔG ^o) correspondingly; and an increasing deviation from full planarity (C _s symmetry) in both the anti and the gauche conformers of the title molecules with increasing ortho halogen atomic size. Only in the anti conformer of 2-fluorobenzoyl chloride does the experimental data refinements suggest close to full planarity for these 2-halobenzoyl chloride molecules.     

Higher hydrates of lithium chloride,lithium bromide and lithium iodide

For lithium halides, LiX (X = Cl, Br and I), hydrates with a water content of 1, 2, 3 and 5 moles of water per formula unit are known as phases in aqueous solid–liquid equilibria. The crystal structures of the monohydrates of LiCl and LiBr are known, but no crystal structures have been reported so far for the higher hydrates, apart from LiI·3H₂O. In this study, the crystal structures of the di‐ and trihydrates of lithium chloride, lithium bromide and lithium iodide, and the pentahydrates of lithium chloride and lithium bromide have been determined. In each hydrate, the lithium cation is coordinated octahedrally. The dihydrates crystallize in the NaCl·2H₂O or NaI·2H₂O type structure. Surprisingly, in the tri‐ and pentahydrates of LiCl and LiBr, one water molecule per Li⁺ ion remains uncoordinated. For LiI·3H₂O, the LiClO₄·3H₂O structure type was confirmed and the H‐atom positions have been fixed. The hydrogen‐bond networks in the various structures are discussed in detail. Contrary to the monohydrates, the structures of the higher hydrates show no disorder.     

Systems of fluorides and bromides of lithium, sodium, and cesium with mono- and invariant monotectic equilibria

Phase diagram with mono- and invariant equilibrium were studied by differential thermal analysis by the example of a system of fluorides and bromides of group 1 s-block elements (lithium, sodium, and cesium). Bordering elements were studied, the quaternary reciprocal system Li,Na,Cs∥F,Br was partitioned into simplexes, and a tree of phases was constructed. The liquidi of the systems LiF-NaBr-CsBr and LiF-NaF-CsBr were constructed, the T-x diagrams of polythermal sections passing through phase separation regions were built, and phases being in equilibrium under specific thermodynamic conditions were described.     

Determination of traces of rubidium in high purity cesium chloride by electrothermal atomic absorption spectrometry (ETAAS) using boric acid as a modifier

The use of boric acid as a modifier for the determination of trace amount of rubidium in high purity cesium chloride matrix by electrothermal atomic absorption is described. It was found that the negative influence of the chloride matrix could not be eliminated using stabilized temperature platform (STPF) alone. Due to the high dissociation energy (D₀ = 427 kJ mol⁻¹) of rubidium chloride, it was difficult to dissociate in the gas phase and hence is lost. Elimination of interferences was achieved by the addition of boric acid as a chemical modifier. Diluted cesium chloride samples (5%, m/v) were analyzed applying the standard addition method. The characteristic mass of 24 pg was obtained. The detection limit of the proposed method is around 26 ng g⁻¹. The developed method was applied to the determination of traces of rubidium in high purity cesium chloride samples. The data obtained by this method were in good agreement with those obtained by other independent method like FAAS.     

Evaluation of some new 14- and 15-crown-formazans as carriers in cesium ion selective electrodes

A number of new crown-formazans with 14 and 15 membered rings have been investigated as selective neutral carriers in cesium ion selective electrodes. Two plasticizers (NPOE and NPBnE) were studied. The new 14-crown-formazan 4a containing the 4-pyridyl N-oxide at the formazyl carbon exhibited the highest selectivity in cesium ion selective electrodes, especially towards the two low selectivity monovalent ions K(+) and NH4(+). Also, membranes containing the plasticizer NPBnE showed better cesium selectivity relative to most ions than those containing NPOE. Membranes containing 4a and variable compositions of plasticizers, potassium tetrakis-(p-chlorophenyl)borate (KTpClPB), and trioctylphosphine oxide (TOPO) were studied in order to prepare an electrode with the optimum cesium selectivity. The highest selectivity for cesium was achieved with the two electrodes designated d and e with membranes containing the ionophore 4a, NPBnE and KTpClPB with and without TOPO. Selectivities are reported relative to sodium, potassium, barium, calcium, ammonium, lithium, cobalt, and magnesium.     

Evaluation of some new 14- and 15-crown-formazans as carriers in cesium ion selective electrodes

A number of new crown-formazans with 14 and 15 membered rings have been investigated as selective neutral carriers in cesium ion selective electrodes. Two plasticizers (NPOE and NPBnE) were studied. The new 14-crown-formazan 4a containing the 4-pyridyl N-oxide at the formazyl carbon exhibited the highest selectivity in cesium ion selective electrodes, especially towards the two low selectivity monovalent ions K⁺ and NH4⁺. Also, membranes containing the plasticizer NPBnE showed better cesium selectivity relative to most ions than those containing NPOE. Membranes containing 4a and variable compositions of plasticizers, potassium tetrakis-(p-chlorophenyl)borate (KTpClPB), and trioctylphosphine oxide (TOPO) were studied in order to prepare an electrode with the optimum cesium selectivity. The highest selectivity for cesium was achieved with the two electrodes designated d and e with membranes containing the ionophore 4a, NPBnE and KTpClPB with and without TOPO. Selectivities are reported relative to sodium, potassium, barium, calcium, ammonium, lithium, cobalt, and magnesium.     

Solubilities, Densities and Refractive Indices of Rubidium Chloride or Cesium Chloride in Ethanol Aqueous Solutions at Different Temperatures

The data of solubilities, densities and refractive indices of rubidium chloride or cesium chloride in the system CEHsOH-H2O were measured by using a simple accurate analytical method at different temperatures, with mass fractions of ethanol in the range of 0 to 1.0. In all cases, the presence of ethanol significantly reduced the solubility of rubidium chloride and cesium chloride in aqueous solution. The solubilities of the saturated solutions were fitted via polynomial equations as a function of the mass fraction of ethanol. The CsC1-C2H5OH-H2O ternary system appeared in two liquid phases： alcoholic phase and water phase, when the mass fractions of ethanol were in the range of 10.37% to 49.59% at 35 ℃. Density and refractive index were also determined for the same ternary systems with varied unsaturated salt concentrations. Values for both experiment and theory were correlated with the salt concentrations and proportions of alcohol in the solutions. The equations proposed could also account for the saturated solutions.     

New data on the chemistry of some of the rare elements

Summary New data are presented concerning the compositions and physicochemical properties of various compounds of some rare elements. The insoluble mixed ferrocyanides formed by various metals with lithium, rubidium, and cesium are reviewed, and new precipitating reagents for these elements are recommended. Regularities to be observed in changes in the compositions of mixed ferrocyanides of rare-earth metals are pointed out. Data are given on the compositions and stabilities of fluorides, oxalates, tartrates, and other compounds of gallium, indium, zirconium, and germanium.(Paper read at a session of the Division of Chemical Sciences of the Academy of Sciences of the USSR, October 31,1957)     

Electrical conductivity of lithium chloride solutions in the propanol-water system

Electrical conduction of lithium chloride solutions in the propanol-water system was studied in the temperature range by using the conductometric method. The electrical conductivity of the solutions was determined in relation to the contents of water and lithium chloride.     

Occurrence and behavior of system peaks in RP HPLC with solely aqueous mobile phases

System peaks are important but often also disturbing phenomena occurring in separation systems. Behavior of system peaks was studied in reversed phase high performance liquid chromatography (RP HPLC) systems consisting of an RP Amide C16 column and aqueous solutions of organic acids with alkaline metal hydroxides as mobile phases. Binary mobile phases, composed of benzoic acid and lithium hydroxide (LiOH) or cesium hydroxide (CsOH), yielded two system peaks. The first peak was stationary and the second one moved with dilution of the mobile phase or with changes of the alkaline metal hydroxide concentration. The latter changes affected dissociation of the benzoic acid present in the mobile phase and thereby its retention. The presumption that the first system peak is not influenced by the type of alkaline metal cation and that it is related to the non‐adsorbed component of the mobile phase was confirmed by a cyclic procedure. Three‐component mobile phases composed of benzoic acid, tropic acid, and a hydroxide gave rise to three system peaks as expected. The first peak was again stationary and the two others shifted depending on the concentration variation of both acids. Resonance causing a zigzag peak, well described in capillary zone electrophoresis (CZE), was observed if 1‐pentanol was injected into a chromatographic system with one‐component mobile phase.     

Nonaqueous Liquid-Liquid Extraction: Extraction of Zinc from Ethylene Glycol Solution of Chloride by Trioctylphosphine Oxide

Abstract

The distribution of zinc between the toluene phase containing trioctylphosphine oxide (TOPO) and the nonaqueous ethylene glycol phase containing either hydrogen or lithium chloride has been investigated by using zinc-65. In the zinc-hydrogen or lithium-chloride-TOPO system, the complex ZnCl₂-2TOPO may predominantly occur in the toluene phase, and only mononuclear zinc complexes appear to exist in the two phases.     

Lithium and Cesium Ion-Pair Acidities of Dibenzyl Ketone. Aggregation of Lithium and Cesium Ion Pairs of the Enolate Ion and Dianion(1)(,)

Spectral study of the cesium and lithium enolates of dibenzyl ketone (DBK) showed that both salts exist as contact ion pairs in THF solutions. The spectral data for the dicesium salt of DBK indicate that it exists as triple ions in which both cations are in contact with the dianion. The dilithium salt of DBK forms triple ions of two types in THF: in one, both cations are in contact with the DBK dianion, in the other, one of the lithium cations is solvent-separated. Evidence for dimerization of the ion pairs was obtained for both lithium and cesium enolates of DBK from UV-vis spectral (blue shift of the absorbance band at higher concentrations) and acidity (the decrease of pK at higher concentrations) studies. The dimerization constant for the cesium enolate of DBK obtained from the acidity data (3.5 x 10(3) M(-)(1)) is considered to be more accurate than that from the spectral analysis (1.7 x 10(3) M(-)(1)). The lithium enolate is much less dimerized than its cesium counterpart with a dimerization constant from acidity data of 4.2 x 10(2) M(-)(1). The first and second cesium pK values of DBK are 18.07 and 33.70, respectively, compared to the first lithium pK of 11.62.