Cesium ammonia

Ruff andZedner have found similar phase separations for lithium-and potassium-ammonia solutions. Kraus and Johnson have confirmed the occurrence of phase separation for lithium-ammonia solution. Hodgins has performed careful vapor pressure and conductance measurements in cesium-ammonia solutions in the concentration range 0.04 M to 7Af but did not find any evidence for phase separation. Kraus has found from vapor pressure measurements that a liquid-liquid phase separation occurs below — 32.5° C and above a concentration of about 2M 5 mole per cent). Also the curve for vapor pressure as a function of concentration indicates the formation of the solid compound Ca(NHj)g at a temperature of — 32.5° C and concentration larger than 4 Af. 

Levy has obtained the valves of T 2 for lithium-, sodium-, potassium-, rubidium- and cesium-ammonia solutions for one concentration in each case. Levy s results confirm Poliak s observation of the relative independence of on the metal ion, although small variations do occur as one goes from one metal to another. In the case of cesium, the concentration 0.5M is probably more than the critical concentration as the relatively small value of 0.2 fisec. obtained by Levy for indicates. 

Iodine Acetaldehyde, acetylene, aluminum, ammonia (aqueous or anhydrous), antimony, bromine pentafluoride, carbides, cesium oxide, chlorine, ethanol, fluorine, formamide, lithium, magnesium, phosphorus, pyridine, silver azide, sulfur trioxide... 

The residue is leached to give cesium sulfate solution, which can be converted to cesium chloride by ion exchange on Dowex 50 resin and elution with 10% HCl, treatment using ammonia or lime, to precipitate the alurninum, or by solvent extraction, followed by purification at neutral pH using hydrogen peroxide or ammonia. 

The performance of many metal-ion catalysts can be enhanced by doping with cesium compounds. This is a result both of the low ionization potential of cesium and its abiUty to stabilize high oxidation states of transition-metal oxo anions (50). Catalyst doping is one of the principal commercial uses of cesium. Cesium is a more powerflil oxidant than potassium, which it can replace. The amount of replacement is often a matter of economic benefit. Cesium-doped catalysts are used for the production of styrene monomer from ethyl benzene at metal oxide contacts or from toluene and methanol as Cs-exchanged zeofltes ethylene oxide ammonoxidation, acrolein (methacrolein) acryflc acid (methacrylic acid) methyl methacrylate monomer methanol phthahc anhydride anthraquinone various olefins chlorinations in low pressure ammonia synthesis and in the conversion of SO2 to SO in sulfuric acid production. 

The NIOSH recommended exposure limit for carcinogenic hexavalent chromium is 1 lg/m Cr(VI) as a 10-h TWA, and for noncarcinogenic Cr(VI) the 10-h TWA is 25 lg/m Cr(VI), including a 15-min maximum exposure of 50 lg/m Cr(VI). According to NIOSH, the noncarcinogenic Cr(VI) compounds are chromic acid and the chromates and dichromates of sodium, potassium, lithium, mbidium, cesium, and ammonia. NIOSH considers any hexavalent chromium compound that does not appear on the preceding Hst carcinogenic (145). 

Sulfobenzyl esters were prepared (cesium salt or dicyclohexylammonium salt, Na03SC6H4CH2Br, DMF, 37-95% yield) from A -protected amino acids. They are cleaved by hydrogenolysis (H2/Pd), or hydrolysis (NaOH, dioxane/water). Treatment with ammonia-or hydrazine results in formation of the amide or hydrazide. The ester is stable to 2 M HBr/AcOH and to CF3SO3H in CF3CO2H. The relative rates of hydrolysis and hydrazinolysis for different esters are as follows ... 

Many other cyclic and noncyclic organic carriers with remarkable ion selectivities have been used successfiilly as active hosts of various liquid membrane electrodes. These include the 14-crown-4-ether for lithium (30) 16-crown-5 derivatives for sodium bis-benzo-18-crown-6 ether for cesium the ionophore ETH 1001 [(R,R)-AA -bisd l-ethoxycarbonyl)undecyl-A,yVl-4,5-tctramcthyl-3,6-dioxaoctancdiamide] for calcium the natural macrocyclics nonactin and monensin for ammonia and sodium (31), respectively the ionophore ETH 1117 for magnesium calixarene derivatives for sodium (32) and macrocyclic thioethers for mercury and silver (33). 

This reaction is similar to 13-1 and, like that one, generally requires activated substrates. With unactivated substrates, side reactions predominate, though aryl methyl ethers have been prepared from unactivated chlorides by treatment with MeO in HMPA. This reaction gives better yields than 13-1 and is used more often. A good solvent is liquid ammonia. The compound NaOMe reacted with o- and p-fluoronitrobenzenes 10 times faster in NH3 at — 70°C than in MeOH. Phase-transfer catalysis has also been used. The reaction of 4-iodotoluene and 3,4-dimethylphenol, in the presence of a copper catalyst and cesium carbonate, gave the diaryl ether (Ar—O—Ar ). Alcohols were coupled with aryl halides in the presence of palladium catalysts to give the Ar—O—R ether. Nickel catalysts have also been used. ... 

Mass Spectrometry. Mass spectrometry holds great promise for low-level toxin detection. Previous studies employed electron impact (El), desorption chemical ionization (DCI), fast atom bombardment (FAB), and cesium ion liquid secondary ion mass spectrometry (LSIMS) to generate positive or negative ion mass spectra (15-17, 21-23). Firm detection limits have yet to be reported for the brevetoxins. Preliminary results from our laboratory demonstrated that levels as low as 500 ng PbTx-2 or PbTx-3 were detected by using ammonia DCI and scans of 500-1000 amu (unpublished data). We expect significant improvement by manipulation of the DCI conditions and selected monitoring of the molecular ion or the ammonia adduction. 

There is apparently no analog of the reaction 2eh H2 in liquid ammonia, where eam is very stable. The loss of paramagnetism in concentrated solutions has been interpreted to be either by formation of (eam)2 or by association with metal cation in neither case is the spectral shift drastic. For Na in ethylenedi-amine (EDA), Dye et al. (1972) measured the rate of 2es— (es)2 as 1.7 x 109 M s-1, which is comparable to that of the corresponding reaction in water, 6 x 109 M-1s, although the products are different. A few rate constants have been measured in cesium-EDA systems, but it is not clear whether the electron or an associated form of the electron and the cation is the reactant. 

All hydroxides (except lithium, sodium, potassium, cesium, rubidium, and ammonia) are insoluble Ba(OH)2 is moderately soluble Ca(OH)2 and Sr(OH)2 are slightly soluble. 

Nitron-, thallium, cesium-, and silver pertechnetate are appreciably soluble in water and therefore less suitable for precipitation and separation of technetium. From aqueous ammonia solution, pertechnetate can be co-precipitated with MgMH PO ... 

The mixed alum solution, on treatment with ammonia or potassium carbonate, forms carbonates of potassium, rubidium and cesium. Rubidium carbonate is separated from other alkab metal carbonates by fractional crystal-bzation (see Rubidium)... 

The compounds MC=CCH3 (M = Na, K) were described earlier.1 The rubidium and cesium derivatives have now been obtained by the reaction of the metals with propyne in liquid ammonia, and their crystal structures studied by X-ray powder diffraction. The compounds are isostructural with those isolated previously, and the c/a ratio in the tetragonal unit cell decreases linearly with the increasing ionic radii of the alkali metals ions.120... 

The complications which result from the hydrolysis of alkali metal cyanides in aqueous media may be avoided by the use of non-aqueous solvents. The one most often employed is liquid ammonia, in which derivatives of some of the lanthanides and of titanium(III) may be obtained from the metal halides and cyanide.13 By addition of potassium as reductant, complexes of cobalt(O), nickel(O), titanium(II) and titanium(III) may be prepared and a complex of zirconium(0) has been obtained in a remarkable disproportion of zirconium(III) into zirconium(IV) and zirconium(0).14 Other solvents which have been shown to be suitable for halide-cyanide exchange reactions include ethanol, methanol, tetrahydrofuran, dimethyl sulfoxide and dimethylformamide. With their aid, species of different stoichiometry from those isolated from aqueous media can sometimes be made [Hg(CN)3], for example, is obtained as its cesium salt form CsF, KCN and Hg(CN)2 in ethanol.15... 

Solutions of alkali metals in liquid ammonia at all concentrations, with the exception of cesium, are less dense than either of the constituents. This behavior for metal ammonia solutions is unique in that the expansion in volume is much larger than that shown on forming solutions of normal electrolytes or non-electrolytes. 

Figure 11. The volume change of cesium in liquid ammonia at —50°C. (data of Hodgins)...

Single crystals of difluoromethane bis(sulfinic acid) anhydride 17 were isolated, after the cesium salt 119 was stored in the presence of traces of water vapor for several weeks <1998JFC(89)55>. Treatment of difluoromethane-l,l-bis(sulfonyl fluoride) 120 with liquid ammonia led to the formation of the cyclic ammonium imide 121 <1997ZNB359, 1997WO9731909>, while reaction of sulfamide 122 with trifluoroacetaldehyde O-ethyl hemiacetal afforded the cyclic aminal 60 (Scheme 41) < 1999S1731 >. 

Treatment of 206 with cesium fluoride in DMF clearly promoted an intramolecular nitro-aldol reaction furnishing, after acetylation, nitrocyclitol 207 as an a, 3-anomeric mixture. Exposure of 207 to liquid ammonia in THF resulted in formation of kinetically favoured a-acetamido derivative 208, probably from a Michael-type addition of ammonia to a nitroolefin intermediate. Reductive elimination of nitro-group in 208 and subsequent deprotection gave validamine 202, in a global 6% yield from glucuronolactone 205. 

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