Uranyl bromide

Diammino-uranyl Bromide, [U02(XH3)2]Br2, is prepared by passing ammonia gas through a solution of uranyl bromide in amyl alcohol till the solution is decolorised and a flocculent yellow precipitate is produced on drying in vacuo the substance is obtained as a yellow amorphous powder, hr properties it resembles the chloride. An ether derivative, of composition [UO2(XH3)2]Cl2.C2H100, is formed if ammonia is passed into an ethereal solution of uranyl bromide. Tri-ammino-uranyl bromide, [U02(XH3)3]Br2, and tetrammino -uranyl bromide, [U02(XH3)4]Br2, are prepared by an analogous method to that for the preparation of the corresponding chlorides, and the properties are similar. 

Uranyl Bromide, UOgBra.— Wlien uranous oxide is heated in a current of bromine vapour a mixture of uranyl bromide and uranous bromide is formed. The former can be exteacted with ether, and obtained as j-ellou-ish-green fluorescent needles by evaporation of the solution. It is obtained in aqueous solution by the action of bromine water on uranous oxide, or of hydrobromic aeid on uranie oxide yellow needles of the heptahydrate, U03Br2.7H20, separate on concentrating the solution. Uranyl bromide is very deliquescent and is decomposed in moist air to hydrated uranic oxide and hydrobromic... 

A bricli-red variety of uranous oxide has been obtained by ealcining uranyl bromide in the air. It is very stable at high temperatures, and is converted to the black modification by heating in hydrogen without any appreciable loss of oxj gen. 

Complexes of uranyl chloride with a variety of oxygen donor ligands continue to be reported, notably with phosphine oxides (55), pyridine N-oxides (27), N,IV-dimethylformamide (7J), acetamide (15), and with the N,IV,IV, IV -tetramethyldicarboxylic acid amides (14), the last being mainly polymeric compounds. A few similar complexes of uranyl bromide (54) and iodide (71) are also known. 

The U(IV) chemistry is similar to that of Th4+, except for the difference in the charge/radius ratio of the ions. U4+ solutions are green in color, stable, and slowly oxidized by air to U02+. Solutions of U4+ are generally prepared by reduction of solutions of the uranyl (U02+) ion. U(IV) forms complexes with many anions (C204-,C2H302, C03-, Cl-, and NO3"). The chlorides and bromides of U(IV) are soluble while the fluorides and hydroxides are insoluble. In aqueous solution, U(IV) hydrolyzes via the reaction,... 

Copolymers of vinyl chloride-vinyl bromide were prepared in bulk using the same conditions in the preparation of PVC, except that only uranyl nitrate was used as in initiator with visible light to avoid photodegradation during polymerization. Thermal analysis of the copolymer indicated random placement of the two comonomers. 

In a study of 58-sec lodine-157 as a delayed neutron emitter in fission products, a novel target arrangement was used (255) This consisted of a hydrochloric acid solution (150 ml, containing 1 ml cone. HCl) of uranyl nitrate to which several milligrams of potassium iodide and bromide carriers,... 

Pure uranous compounds may be prepared by precipitating U(OH)4 from aqueous solution with ammonium hydroxide and dissolving the precipitate in the appropriate acid. Uranous sulfate, the most common salt, is soluble in water, as are the chloride, bromide, and iodide. Uranous nitrate is unstable, gradually undergoing oxidation to uranyl nitrate with liberation of oxides of nitrogen. 

Solutions of uranyl salts can be readily prepared by dissolving UO3 in the appropriate acid. Uranyl nitrate, sulfate, acetate, fluoride, chloride, bromide, and iodide aU are very soluble, the solutions having a characteristic yellow-green fluorescence. Uranyl nitrate can be made by dissolving uranium metal or any of the oxides in nitric acid. It crystallizes from solution as the well-formed yellow uranyl nitrate hexahydrate U02(N03)2 6H2 0, often called UNH. 

Carey Lea failed to find any sensitising action of dyes on ferric oxalate, potassium chromate, uranyl nitrate, etc. The research of J. M. Eder was fundamental in the study of sensitisation by dyestuffs. J. J. Acworth found a rough correlation between the absorption maximum of a coloured silver bromide gelatin plate and the maximum of chemical activity in the region of the spectrum, although this was always displaced towards the violet. The development of this work into panchromatic plates is well known. 

Figure 2(right) is an enlargement of a favorable area of dioctadecyldimethylaramonium bromide(D0AB n=17) stained negatively by uranyl acetate. The electron-dense materials... 

Figure 2. Electron micrograph of 1,2-dipalmitoyl-L-phosphatidylcholine stained by phosphotungstic acid(left) and dioctadecyl-dimethylammonium bromide stained by uranyl acetate(right).

Uranyl ion-containing products were synthesized as described in the previous paper. Infrared spectra were obtained employing potassium bromide pellets utilizing a Perkin-Elmer Model 457 grating spectrophotometer. Mass spectra were obtained using a coupled pyroprobe-mass spectrometer as described in ref. 2. 

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