Uranium(III) chloride

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ImageFile = Uranium(III)-chloride-3D-polyhedra.png IUPACName = Uranium(III) chloride
OtherNames = Uranium chloride,
Uranium trichloride
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CASNo = 10025-93-1
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U = 1 | Cl = 3
Appearance = Green crystalline solid
Density = 5.500 g/cm³, liquid
MeltingPtC = 837
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BoilingPtC = 1657
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Solubility = Soluble
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OrbitalHybridisation = Tricapped trigonal prismatic
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Autoignition = Non-flammable
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OtherCpds = Uranium(IV) chloride, Uranium(V) chloride, Uranium(VI) chloride

Uranium(III) chloride , UCl₃, is a chemical compound that contains the earth metal uranium and chlorine. UCl₃ is used mostly to reprocess spent nuclear fuel. Uranium(III) chloride is synthesized various ways from uranium(IV) chloride; however, UCl₃ is less stable than UCl₄.

Preparation

There are two ways to synthesize uranium(III) chloride. The following processes describe how to produce uranium(III) chloride.

(1) In a mixture of NaCl-KCl at 670-710 °C, add uranium tetrachloride with uranium metal.:3UCl₄ + U → 4UCl₃ [Serrano, K.; Taxil, P.; Dugne, O.; Bouvet, S.; Puech, E. J. Nucl. Mater. 2000, 282, 137–145.]

(2) Heat uranium(IV) chloride in hydrogen gas.:2UCl₄ + H₂ → 2UCl₃ + 2HCl [Remsen, Ira. Inorganic Chemistry. New York: Henry Holt and Company, 1890.]

Properties

In solid uranium(III) chloride each uranium atom has nine chlorine atoms as near neighbours, at approximately the same distance, in a tricapped trigonal prismatic configuration. [ Wells A.F. (1984) "Structural Inorganic Chemistry" 5th edition Oxford Science Publications ISBN 0-19-855370-6 ]

Uranium(III) chloride is a green crystalline solid at room temperature. UCl₃ melts at 837 °C and boils at 1657 °C. Uranium(III) chloride has a density of 5500 kg/m³ or 5.500 g/cm³.

Its composition by weight::Chlorine: 30.84%:Uranium: 69.16%

Its formal oxidative states::Chlorine: −1:Uranium: +3

Uranium(III) chloride is very soluble in water and is also very hygroscopic. UCl₃ is more stable in a solution of hydrochloric acid. [Comey, Arthur M. and Hahn, Dorothy A. A Dictionary of Chemical Solubilities: Inorganic. New York: The MacMillan Company, 1921.]

Uses

Reagent

Uranium(III) chloride is used in reactions with tetrahydrofuran (THF) and sodium methylcyclopentadiene to prepare various uranium metallocene complexes. [Brenna, J.G.; Anderson, R.A.; Zalkin, A. Inorg. Chem. 1986, 25, 1756–1760.]

Catalyst

Uranium(III) chloride is used as a catalyst during reactions between lithium aluminium hydride (LiAlH₄) and olefins to produce alkyl aluminate compounds. [Le Marechal, J.F.; Ephritikhine, M.; Folcher, G. J. Organomet. Chem. 1986, 309, C1–C3]

Molten form

The molten form of uranium(III) chloride is a typical compound in pyrochemical processes as it is important in the reprocessing of spent nuclear fuels.Okamoto, Y.; Madden, P.; Minato, K. J. Nucl. Mater. 2005, 344, 109–114.] UCl₃ is usually the form that uranium takes as spent fuel in electrorefining processes. [Okamoto, Y.; Kobayashi, F.; Ogawa, T. J. Alloys Compd. 1998, 271, 355–358.] ,

Hydrates

There are three hydrates of uranium(III) chloride:
#UCl₃^.2H₂O^.2CH₃CN
#UCl₃^.6H₂O
#UCl₃^.7H₂O

Each are synthesized by the reduction of uranium(IV) chloride in methylcyanide (acetonitrile), with specific amounts of water and propionic acid. [Mech, A.; Karbowick, M.; Lis, T. Polyhedron. 2006, 25, 2083–2092.]

Precautions

While there are no long-term data on the toxic effects thas UCl₃, it is important to minimize exposure to this compound when possible.

Similar to other uranium compounds that are soluble, UCl₃ is likely absorbed into the blood through the alveolar pockets of the longs within days of exposure. Exposure to uranium(III) chloride leads to toxicity of the renal system. [Bertell, Rosalie. "Gulf War Veterans and Depleted Uranium." May 1999. Available: http://ccnr.org/du_hague.html]

References

External links

* [http://www.webelements.com/webelements/compounds/text/U/Cl3U1-10025931.html Uranium(III) chloride information at Webelements]
* [http://ibilabs.com/Uranium%20Chloride,%20tri.htm Uranium(III) chloride information at International Bio-Analytical Industries, Inc.]