Cesium metal reactions with

Without either spray droplets or flooded pathways, substantial fractions of radionuclides released from the degrading reactor fuel can be retained within the reactor coolant system. Results of some example calculation for radionuclide retention in the reactor coolant systems for various types of accidents are shown in Table III-l. The natural retention of radionuclide vapors oeeurs because the vapors either condense on surfaces or react with these surfaces. Depending on the surface temperature and the duration of its exposure to high temperature steam, the surface material is either ehromium oxide (Cr203) or iron oxide (Fe304 y). Both of these materials are expected to be reactive toward cesium-bearing vapours and strontium or barium vapors. Stainless steel lead screws above the core at Three Mile Island were found to have captured cesium by reaction with silica impurities in the steel. Metallic nickel inclusions in the oxide films on surfaces within the reactor coolant system are reactive toward tellurium whether it is in the metallic state or present as TeO or SnTe. 

More general procedures for additions of halogen fluorides to highly fluori-nated olefins involve reactions with a source of nucleophilic fluoride ion, such as an alkali metal fluoride, in the presence of aposttive halogen donor [62 107, lOff, 109, 110, 111] (equations 11 and 12) These processes are likely to occur by the generation and capture of perfluorocarbamonic intermediates Tertiary fluormated carbanions can be isolated as cesium [112], silver [113], or tns(dimethylamino)sul-... 

Gomplexation of cesium at a tetracarbaborane cage was achieved in the reaction of [ / >-2,4,6,12-(SiMe3)4-2,4,6,12-C4B8H8] with an excess quantity of cesium metal in THF. In the polymeric structure of the cesium salt, one cesium atom occupies an apical position above an open six-membered C3B3 face 5.19... 

Metals react with nonmetals. These reactions are oxidation-reduction reactions. (See Chapters 4 and 18). Oxidation of the metal occurs in conjunction with reduction of the nonmetal. In most cases, only simple compounds will form. For example, oxygen, 02, reacts with nearly all metals to form oxides (compounds containing O2-). Exceptions are the reaction with sodium where sodium peroxide, Na202, forms and the reaction with potassium, rubidium, and cesium where the superoxides, K02, Rb02, and Cs02 form. 

Cesium chloride (CsCl) is produced by the reaction of cesium metal with chlorine gas (Ca + Cl —> CsCl). It is also used in the beer brewing industry, to coat fluorescent screens, and to improve the taste of mineral water. 

Rate studies of the reaction between cesium and water in ethylenediamine, using the stopped-flow technique, have been extended to all alkali metals. The earlier rate constant (k — 20 NT1 sec.-1) and, in some cases, a slower second-order process (k — 7 Af"1 sec.-1) have been observed. This is consistent with optical absorption data and agrees with recent results obtained in aqueous pulsed-radiolysis systems. Preliminary studies of the reaction rate of the solvated electron in ethylenediamine with other electron acceptors have been made. The rate constant for the reaction with ethylene-diammonium ions is about 105 NCl sec.-1 Reactions with methanol and with ethanol show rates similar to those with water. In addition, however, the presence of a strongly absorbing intermediate is indicated, which warrants more detailed examination. 

The reactions of all the alkali metals with water, of cesium and rubidium with methanol, of cesium with ethanol, and of cesium with HC1 and with NH4Br have been examined. Figure 1 shows a typical oscilloscope trace, and Figure 2 shows a plot of log absorbance vs. time for this trace. The reaction is pseudo-first-order in metal (since solute concentration is ten or more times greater than metal concentration), and the overall rate constants and their order in solute are obtained by varying solute concentration. 

Vanadium oxytrichloride is a lemon-yellow liquid. Its boiling point is 124.5°C. at 736 mm. and 127.16°C. at 760 mm. It remains liquid at —77°. The vapor pressure at —77° is 4.1 mm. at 0°, 21 mm. and at 85°C., 270 mm. Its density in grams per milliliter is 1.854 at 0° and 1.811 at 32°C. At ordinary temperatures, it neither dissolves nor reacts with carbon, hydrogen, nitrogen, oxygen, silicon, tellurium, or metals except the alkali metals and antimony. The reactions with the alkali metals are explosive at characteristic temperatures, varying from 30°C. for cesium to 180°C. for sodium (lithium not determined). Small... 

In 1967 POF3 was reported to react with cesium fluoride to give Cs+[P02F2] and Cs+[PF6] (86). More recent work by Selig and Aminadav (59) has shown that reaction with alkali metal and nitrosyl fluorides in a 1 1 ratio yields [PF6] as the only fluorine-containing species. Primary and secondary negative-ion formation observed in the... 

The following contribution is intended to continue our earlier review [6] dealing with the then known cesium assisted ractions only some very important earlier cesium assisted reactions are described here for the sake of completeness After a short description of the properties of some cesium compounds used in this respect in organic synthesis, those reactions are discussed that have been published more recently and which proceed under the intermediate formation of organic cesium salts at oxygen, nitrogen or sulphur functions. Only those cyclization reactions are considered which allow a direct comparison of the yields obtained with cesium compounds or cesium metal. The description starts with reactions leading to the formation of C—C bonds and proceeds to the syntheses of ethers, lactones, amines and sulfides. The discussion ends with a summary of the attempts to explain the cesium effect . 

In the series of the alkali metal carbonates and -hydroxides the cesimn compounds are the strongest bases [14]. For reasons of simpler handling the less hygroscopic carbonate is often preferred to the hydroxide. In dipolar aprotic solvents, carboxylic acids [15], phenols [16], thiols [17, 18] and sulfonamides [19] are easily deprotonated by cesium carbonate, whereas with carbamates such as e.g. benzyloxycarbonyl- ( Z -)protected amino acids no reaction occurs [20]. 

The use of cesium compounds in C—C bond formation reactions has so far been limited to a few cases. Vogtle and KiUener [21] observed that the use of cesium metal in the Mtiller-Rdscheisen procedure [22] of the Wurtz coupling reaction of p-xylylene dibromide, intended to yield [2 ]paracyclophanes 1, leads to the [23]paracyclophane lb with the highest yield compared to other alkali metals. The yields of the other cyclic compounds Ic-e thereby are much lower compared to the application of sodium metal (Fig. 1) [23]. 

SAFETY PROFILE A highly corrosive irritant to the eyes, skin, and mucous membranes. Mildly toxic by inhalation, Explosive reaction with alcohols + hydrogen cyanide, potassium permanganate, sodium (with aqueous HCl), tetraselenium tetranitride. Ignition on contact with aluminum-titanium alloys (with HCl vapor), fluorine, hexa-lithium disilicide, metal acetylides or carbides (e.g., cesium acetylide, rubidium ace-tylide). Violent reaction with 1,1-difluoro-ethylene. Vigorous reaction with aluminum, chlorine + dinitroanilines (evolves gas). Potentially dangerous reaction with sulfuric acid releases HCl gas. Adsorption of the acid onto silicon dioxide is exothermic. See also HYDROGEN CHLORIDE (AEROSOL) and HYDROCHLORIC ACID. 

Ignition on contact with bromine pentafluoride (or violent reaction), chlorine trifluoride, fluorine, metals (powdered) + water, aluminum-titanium alloys + heat, metal acetylides (e.g., cesium acetylide, copper(I) acetylide, lithium acetylide, mbidium acetylide), nonmetals (e.g., boron ignites at 700°C), phosphoms, sodium phosphinate. Violent reaction with acetaldehyde, aluminum + diethyl ether, dipropylmercury, titanium (above 113°C). Incandescent reaction with cesium oxide... 

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