Uranium iodides

Uranium hydroxides, 25 430 Uranium iodides, 25 439 Uranium isotopes, 25 391, 392-394 alternative separation methods for, 25 417... 

Preparation. Uranium metal may be prepared by several methods the reduction of uranium oxides with carbon In an arc-melting furnace reduction of uranium oxides with magnesium, aluminum, calcium or calcium hydride the reduction of uranium halides with alkali or alkaline-earth metals electrolytic reduction of uranium halides and the themal decomposition of uranium Iodide. 

Bromides and Iodides. The red-brown tribromide, UBr [13470-19-4], and the black tniodide, Ul [13775-18-3], may both be prepared by direct interaction of the elements, ie, uranium metal with X2 (X = Br, I). The tribromide has also been prepared by interaction of UH and HBr, producing H2 as a reaction product. The tribromide and tniodide complexes are both polymeric soflds with a local bicapped trigonal prismatic coordination geometry. The tribromide is soluble in H2O and decomposes in alcohols. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

Iodargyrite, natural occurrence of, 22 668 Iodates, 14 374-375 Iodate solutions, 14 362 Iodic acid, 14 375 Iodide analysis, of water, 26 41 Iodide ion, 14 367-368 25 488 Iodide-refining method, 26 149 for vanadium, 25 520 Iodides, 14 374 thorium, 24 763 tungsten, 25 379-380 uranium, 25 439... 

The conductivities of thorium (III) and uranium (IV) halides in nitromethane are increased in the presence of a donor molecule from chloride to iodide and they also increase with increasing donicity of the neutral donor 49-53)... 

Major constituents (greater than 5 mg/L) Minor constituents (O.Ol-lO.Omg/L) Selected trace constituents (less than 0.1 mg/L) Bicarbonate, calcium, carbonic acid, chloride, magnesium, silicon, sodium, sulfate Boron, carbonate, fluoride, iron, nitrate, potassium, strontium Aluminum, arsenic, barium, bromide, cadmium, chromium, cobalt, copper, gold, iodide, lead, Uthium, manganese, molybdenum, nickel, phosphate, radium, selenium, silver, tin, titanium, uranium, vanadium, zinc, zirconium... 

Volatile protactinium pentaehloride has been prepared in a vacuum by reaction of the oxide with phosgene at 550° C or with carbon tetrachloride at 200°C. Reduction of this at 600°C with hydrogen leads to protactinium(IV) tetrachloride, Pad. which is isostructural with uranium(IV) tetrachloride, UCI4. The pentaehloride can be converted into the bromide or iodide by heating with the corresponding hydrogen halide or alkali halide... 

The trichloride, tnbromide and triiodide of uranium are obtained either by reaction of the elements or by treatment of UH3 with the appropriate halogen acid. The thermal stability of the halides decreases as the atomic number of the halogen increases. No higher uranium bromides or iodides are known. 

The detonation of nitrogen iodide by nuclear fission was first reported by Feenberg (Ref 13). Small samples of nitrogen iodide mixed with black uranium oxide were exposed to a 20Qmg Ra-Be neutron source surrounded by 6cm of paraffin. A typical sample contd l/2g uranium... 

P. Fabre, C. Magnor H. Muraour, Detonation of Nitrogen Iodide hv Fragments of the Uranium Nucleus Bombarded by Neutrons ,... 

The recovery of important metals or their salts is possible by electrolysis in cells provided with ion-selective membranes, e.g. of uranium (71, 72, 73, 75), of magnesium from sea water (130), of iodine from iodide containing brines (158), of manganese (74). 

This is a convenient, facile, and high-yield preparative route for quantitative preparation of the complexes above no special equipment is required. UI3(THF)4 crystallizes in a P2x/c space group. It is mononuclear with pentagonal-pyramidal coordination geometry around the central uranium atom. This compound is stable until 75°C, then THF molecules are removed by steps, forming UI3 at 162°C. Lewis base adducts of uranium tri-iodide, such as UI3(THF)4 above, are synthetically useful precursors for trivalent uranium chemistry (see Sec. 5.3.2) [360]. 

In the glovebox, 18.2g (99.3 mmol) of NaN(SiMe3)2 was placed in a 250-mL Erlenmeyer flask and 100 mL of THF added. Then a 1-L Erlenmeyer flask was charged with 30.Og (33.1 mmol) of UI3(THF)4, a 1-in. Teflon-coated stir bar, and 300mL of THF. The sodium silylamide solution was added to the stirred uranium tri-iodide solution over a period of 1 hr to produce a... 

The list of intensifier formulas includes uranium, silver, copper, selenium, chromium, mercuric chloride, and mercuric iodide. Some of the formulas, such as uranium, create a high degree of intensification but a low degree of stability. Others, such as chromium, do not intensify nearly as well, but the image is reputedly quite stable. 

A pure acetonitrile complex of uranium(IV) iodide cannot be isolated,8 but the salt [(CeHj As UI (red) can be readily prepared by the procedure described above in subsection 1, the pure halide being used instead of the acetonitrile complex. f( C H )4NJPaBr6 is extremely soluble in acetonitrile but it can be isolated in 100% yield by room-temperature evaporation of the solvent containing equimolar amounts of the component bromides. 

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