Cesium oxide

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... 

Cesium Oxides. Cesium forms a series of oxides, including cesium monoxide [20281-00-9] mol wt 281.81, theoretical cesium content... 

Other Applications. The refractive index of siUcate or borosiUcate glass can be modified by the addition of cesium oxide, introduced as cesium nitrate or carbonate. Glass surfaces can be made resistant to corrosion or breakage by surface ion exchange with cesium compound melts or solutions. This process can also be used for the production of optical wave guides (61). 

Base catalysis is another area which has received a recent stimulus from developments in materials science and microporous solids in particular. The Merk company, for example, has developed a basic catalyst by supporting clusters of cesium oxide in a zeolite matrix [13]. This catalyst system has been developed to manufacture 4-methylthiazole from acetone and methylamine. 

In the last decade, the mesoporous molecular sieve MCM-41 has been developed (2S2) and applied as a catalyst to many acid-catalyzed reactions (2SS). However, until now, comparatively few investigations of mesoporous molecular sieves as base catalysts have been reported (169,211-214,234,235). For example, sodium- and cesium-exchanged mesoporous MCM-41 were shown to be mildly selective, water-stable, recyclable catalysts for the base-catalyzed Knoevenagel condensation, and mesoporous MCM-41 containing intraporous cesium oxide particles prepared by impregnation with aqueous cesium acetate and subsequent calcination was found to have strong-base activity for the Michael addition (211,213) and rearrangement of co-phenylalkanals to phenyl alkyl ketones (212). 

Cesium chloride is prepared by the treatment of cesium oxide or any cesium salt with hydrochloric acid followed by evaporation and crystallization of the solution. 

An acidity scale has been proposed in which the difference in the acidity parameters. (aB — aA), of a metal oxide and a nonmetal oxide is the square root of the enthalpy of reaction of the acid and base.4 Thus for reaction 9.5, the enthalpy of reaction is —8fikJ mol-1 and so the a values of CaO and SiO, differ by about 9 units. Selected values are fisted in Table 9.1. Although based on the Lux-Flood concept, the values are obviously of more general interest. The most basic oxide, as expected, is cesium oxide, amphoteric oxides have values near zero (water was chosen to calibrate the scale at a value of 0.0). and the most acidic oxide is CLO,. the anhydride of perchloric acid. 

Ballard, James W., Infrared sensitivity of cesium oxide... 

A potential curve of an endothermically chemisorbed atom or molecule represents an excited state with respect to the normal state of the physically adsorbed atom or molecule. When cesium atoms are adsorbed on salt layers or on cesium oxide, they are adsorbed as atoms and not, as they would be on metal surfaces, as ions. Ionization can be brought about by absorption of light 172) or by thermal excitation (173). 

When oxygen is acting on cesium at room temperature the mobility of the cesium atoms is so high that a polyatomic layer of cesium atoms forms on top of any oxide layer that has been formed. We may also say that, apparently, the cesium oxide is absorbed by the metal, i.e., it is dissolved in the cesium. The appearance of the surface is unchanged, and so is its photoelectric behavior. Only after the cesium has been almost completely oxidized on continuous supply of oxygen, does a very thin adsorbed cesium layer appear on the cesium oxide and does the photoelectric current temporarily rise sharply until, on further supply of oxygen, also these last cesium atoms are converted into oxide. 

Fig. 2.39 Cesium oxide loaded MCM-41 as a catalyst for the Michael addition.

Recently, two types of surfaces with coadsorbed cesium and oxygen have shown promise for low work function operation in thermionic converters. The first type of surface is made by codeposition of a "thick layer" ( 30 A) of cesium. As shown in Figure 13 ij), if the proportions of cesium and oxygen are properly controlled, a work function as low as 1.0 ev can be obtained. The substrate material does not affect the low obtained with a thick Cs - 0 layer. This type of surface could potentially be maintained in a thermionic converter by an equilibrium mixture of cesium, oxygen, and cesium oxide. Experiments to demonstrate this in operating diodes are underway ( ). 

Hansen, L. K. and Woo, H. "Thermionic Converters with a Thick Cesium Oxide Collector", IEEE International Conference on Plasma Science, Madison, Wisconsin, 1980, 75. 

PROP Bright, shiny, hexagonal crj stals silver-white, ductile metal or possibly a silvery liquid. Golden when ultra pure. Spontaneously ignites in the atmosphere forming cesium oxides, carbonates and hydroxide. Mp 28.5°, bp 668°, d 1.873, vap press 1 mm 279°. Reacts violently with H2O forming CsOH and dihydrogen. SYN CESIUM-133... 

Violent reaction with alcohols, N-aryl sulfinamides, dimethyl formamide, polychlorobiphenyl, sodium hydroxide, hydrochloric acid + dinitroanilines. Incandescent reaction when warmed with cesium oxide (above 150°), tellurium, arsenic, tungsten dioxide. Potentially dangerous reaction with hydrocarbons + Lewis acids releases toxic and reactive HCl gas. 

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... 

The conversion of acetone to methyl isobutyl ketone (MIBK) also uses a combination of base catalysis with a hydrogenation catalyst [35], The base component converts the acetone to diacetone alcohol (DAA) via an aldol reaction, which is then dehydrated by the silica to give mesityl oxide (MO). The final step is the hydrogenation of the MO to MIBK over the metal component. The action of the base catalyst in the absence of the hydrogenating metal has been studied [36]. As well as the aldol condensation reactions shown below, the cesium oxide also hydrogenated MO to MIBK, albeit at a low level (Scheme 21.3). 

Cesium hydroxide (CsCSl) Cesium hydroxide, ion (CsOH ) Cesium oxide (OO)... 

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