Cesium preparation

It can be isolated by elecytrolysis of the fused cyanide and by a number of other methods. Very pure, gas-free cesium can be prepared by thermal decomposition of cesium azide. 

Rubidium can be liquid at room temperature. It is a soft, silvery-white metallic element of the alkali group and is the second most electropositive and alkaline element. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen. As with other alkali metals, it forms amalgams with mercury and it alloys with gold, cesium, sodium, and potassium. It colors a flame yellowish violet. Rubidium metal can be prepared by reducing rubidium chloride with calcium, and by a number of other methods. It must be kept under a dry mineral oil or in a vacuum or inert atmosphere. 

Xenates and Perxenates. Alkali metal xenates of composition MHXe04-1.5H20, where M is sodium, potassium, mbidium, or cesium, have been prepared by free2e-dryiQg mixtures of xenon trioxide and the corresponding metal hydroxides ia 1 1 molar ratios. The xenates are unstable, explosive solids. 

Group 13 (IIIA) Perchlorates. Perchlorate compounds of boron and aluminum are known. Boron perchlorates occur as double salts with alkah metal perchlorates, eg, cesium boron tetraperchlorate [33152-95-3] Cs(B(C104)4) (51). Aluminum perchlorate [14452-95-3] A1(C104)2, forms a series of hydrates having 3, 6, 9, or 15 moles of water per mole of compound. The anhydrous salt is prepared from the trihydrate by drying under reduced pressure at 145—155°C over P2O5 (32). 

The ozonides are characterized by the presence of the ozonide ion, O - They are generally produced by the reaction of the inorganic oxide and ozone (qv). Two reviews of ozonide chemistry are available (1,117). Sodium ozonide [12058-54-7] NaO potassium ozonide [12030-89-6] 35 rubidium ozonide [12060-04-7] RbO and cesium ozonide [12053-67-7] CsO, have all been reported (1). Ammonium ozonide [12161 -20-5] NH O, and tetramethylammonium ozonide [78657-29-1/, (CH ) NO, have been prepared at low temperatures (118). 

Potassium Graphite. Potassium, mbidium, and cesium react with graphite and activated charcoal to form intercalation compounds CgM, C24M, C gM, C gM, and C qM (61,62). Potassium graphite [12081 -88-8] 8 P gold-colored flakes, is prepared by mixing molten potassium with graphite at 120—150°C. 

Rubidium was discovered ia 1861 by Bunsen and Kirchoff by means of an optical spectroscope. It was named for the prominent red lines ia its spectmm, from the Latin word rubidus meaning darkest red. Bunsen prepared free mbidium duriag the same year by an electrolytic method. After cesium, mbidium is the second most electropositive and alkaline element. The two isotopes of natural mbidium are Rb [13982-12-1] (72.15%) and Rb [13982-13-3] (27.85%). The latter is a beta-emitter having a half-life of 4.9 x 10 ° yr. Twenty-four isotopes of mbidium are known. 

No tniodoarsorane has been reported. Triduorodiphenylarsorane [2357-18-8] C22H2QASF2, has been prepared by several methods. One method involves the reaction of benzene with arsenic pentafluoride and subsequent treatment of the resulting salt with cesium fluoride (147) ... 

Thermal Decomposition. Cesium a2ide [22750-57-8] CsN, which is prepared by reacting aqueous solutions of cesium sulfate and barium a2ide, melts at 326°C and decomposes at 390°C to cesium metal (32) ... 

Cesium Halides. Cesium bromide, [7787-69-1], CsBr, mol wt 212.82, theoretical cesium content 62.45%, is a colorless crystalline soUd, having a melting point of 636°C, a specific gravity of 4433 kg/m, and a solubUity of 1.23 kg/L of water at 25°C. It is usuaUy prepared by neutrali2ing the carbonate or hydroxide with HBr, but it is also the primary product of the Dow process (25) for poUucite processing. 

Cesium isotopes can be recovered from fission products by digestion in nitric acid, and after filtration of waste the radioactive cesium phosphotungstate is precipitated using phosphotungstic acid. This technique can be used to prepare radioactive cesium metal or compounds. Various processes for removal of Cs isotopes from radioactive waste have been developed including solvent extraction using macrocycHc polyethers (62) or crown ethers (63) and coprecipitation with sodium tetraphenylboron (64). 

The carboxamidomethyl ester was prepared for use in peptide synthesis. It is formed from the cesium salt of an A-protected amino acid and a-chloroacetamide (60-85% yield). It is cleaved with 0.5 M NaOH or NaHCOa in DMF/H2O. It is stable to the conditions required to remove BOC, Cbz, Fmoc, and r-butyl esters. It cannot be selectively cleaved in the presence of a benzyl ester of aspartic acid. ... 

The Tcrom ester is prepared from the cesium salt of an N-protected amino acid by reaction with 2-(trifluoromethyl)-6-chromylmethyl bromide (DMF, 25°, 4 h, 53-89% yield). Cleavage of the Tcrom group is effected by brief treatment with n-propylamine (2 min, 25°, 96% yield). It is stable to HCl/dioxane, used to cleave a BOC group. ... 

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 ... 

Similar compounds to those described above have been prepared by the same group using the bis-cesium salts of pyridine-3,5-dicarboxylic acids. In a number of experiments Piepers and Kellogg showed that Cs plays an irreplacable role as compared with Na", K and Rb for the formation of [the macrocycle shown below] . 

Fluoroncytrifluoromethane is prepared in a process that uses cesium fluoride as a catalyst for the reaction between fluorine and carbon monoxide [/ij (equation 1) Bisfluoroxydifluoromethane is prepared in a similar manner from carbon dioxide [id], Fluoroxymethane was prepared recently [14]... 

Cesium fluoroxy sulfate [5, dl is prepared by reacting fluorine with cesium sulfate in aqueous solution [20, 21] (equation 3). 

The white cesium fluoroxy sulfate precipitates from the reaction medium and may be kept for several months in the cold (0 to -15 °C) Metal surfaces can cause detonation of the reagent. The reaction scope of cesium fluoroxysulfate seems narrower than that of acetyl hypofluorite because of its limited solubility in organic solvents Cesium fluoroxysulfate has not been prepared with a fluorine-18 label. 

Fluororesorcinol can be prepared from derivatives of resorcinol and fluo-roxytrifluoromethane [15, 24] (equation 4) or by fluorination of resorcinol with cesium fluoroxysulfate [25] (equation 5). Reaction of acetyl hypofluorite with M-acetyl-O-methyltyrosine methyl ester provides a good route to 3-fluorotyrosine derivatives [26] (equation 6). 

The nucleophilic displacement of halogens by pentafluorophenoxide ion resulted in the formation of the corresponding esters [31] (equation 29) (Table 12). Reactions of trifluoromethanesulfinyl fluoride with fluoro alcohols in the presence of sodium fluoride or cesium fluoride are used to prepare sulfmates [32] (equation 30) (Table 12). 

Rearrangement of fluorine with concomitant ring opening takes place in fluorinated epoxides Hexafluoroacetone can be prepared easily from perfluo-ropropylene oxide by isomerization with a fluorinated catalyst like alumina pre treated with hydrogen fluoride [26, 27, 28] In ring-opening reactions of epoxides, the distribution of products, ketone versus acyl fluoride, depends on the catalyst [29] (equation 7) When cesium, potassium, or silver fluoride are used as catalysts, dimenc products also are formed [29]... 

NMR spectroscopy is ideal for detecting charged fluorinated intermediates and has been applied to the study of increasingly stable carbocation and carbanion species. Olah [164, 165] has generated stable fluorocarbocations m SbFj/SOjClF at low temperatures The relatively long-lived perfluoro-rerr-butyl anion has been prepared as both the cesium and tris(dimethylamino)sulfonium (TAS) salts by several groups [166, 167, 168], Chemical shifts of fluonnated carbocations and carbanions are listed m Table 23. 

The Tcrom ester is prepared from the cesium salt of an A-protected amino acid by reaction with 2-(trifluoromonethyl)-6-chromonylmethyl brormde (DMF, 25°,... 

Other recent works in this field, studies on the transport of alkali and alkaline earth cations with p-zerr-butyl calix[n]arene esters and amides, were carried out by Arnaud-Neu et al. [20] and Casnati et al. [21]. They prepared 1,3-alternate calix[4]arene-crown-6 as a new class of cesium selective ionophore. 

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