Uranium oxides, decompositions

Uranium can be prepared by reducing uranium halides with alkali or alkaline earth metals or by reducing uranium oxides by calcium, aluminum, or carbon at high temperatures. The metal can also be produced by electrolysis of KUF5 or UF4, dissolved in a molten mixture of CaCl2 and NaCl. High-purity uranium can be prepared by the thermal decomposition of uranium halides on a hot filament. 

Thermal decomposition of Pa20F8 (217) at 220-290°C yields a white solid, Pa02F, which also decomposes to Pa3OvF, which is also white, at 560-580°C. Thermal decomposition of U2OF8 does not follow the same path as that of Pa20F8, and UO2F is not formed (215). However, uranium oxide phases close to this composition have been reported, and their structures have been shown to contain O-U-O chain structures (219). 

The fusion of uranium oxides with alkali or alkaline earth carbonates, or thermal decomposition of salts of the uranyl acetate anion, gives orange or yellow materials generally referred to as uranates, for example,... 

Although there are a number of reported methods for preparing uranium hexachloride, most of them can be grouped under two types.(1) Uranium hexachloride can be prepared by further chlorination of lower uranium chlorides. This type includes those preparations in which a uranium oxide is the starting material, since a lower uranium chloride is normally formed as an intermediate in these chlorination reactions. (2) Uranium hexachloride is formed in the thermal decomposition of uranium pentachloride. Neither method yields uranium hexachloride in a very pure form. Uranium/chlorine ratios of 1 5.8 to 5.9 are normally the best encountered. 

Preparation of Uranyl Metaborate. An anhydrous boric oxide glass is prepared by thermal decomposition of boric acid in a platinum dish. The uranium oxide powder is then spread on the surface of the boric oxide, and the reactants are heated in air at — 1000°C. until Reaction 1... 

Uranium oxides Interpretation of observations for the dissociations of uranium oxides (and hydroxides) are complicated by the large number of phases and solid solutions mentioned in the literature. Karkahnavala and Phadnis [76] conclude that the thermal stabilities of the following phases increase with symmetry. The same sequence is shown by the enthalpies, rates and values of for these reactions, decomposition temperatures are shown in brackets ... 

Studies of the decomposition of methanol over various catalysts show that the same catalysts are active toward the decomposition reaction cat pressures of one atmosphere as are active toward the synthesis at the higher pressures. Indeed, to Patart is attributed the statement that the results from the work of Sabatier on the catalytic decomposition of methanol led directly to the use of certain of the methanol synthesis catalysts.188 144 Smith and Hawk 145 found that zinc oxide made by igniting die carbonate, mixtures of zinc and chromium oxides in the atomic proportions of 4 zinc to 1 chromium, mixtures of zinc and uranium oxides,... 

BENZINOFORM (56-23-5) Becomes corrosive on contact with water. Explosive reaction on contact with burning wax or uranium, alkali metals, potassium sulfur diimide, triethylalu-luinum, triethyldialuminum trichloride. Oxidative decomposition at elevated temperatures ... 

---