Uranyl chloride
Uranyl chloride
Names
IUPAC name
Dichlorodioxouranium
Other names
Uranium(VI), dichlorodioxy
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.315
EC Number
  • 232-246-1
UNII
  • hydrate: InChI=1S/2ClH.H2O.2O.U/h2*1H;1H2;;;/q;;;;;+2/p-2
    Key: DPJRXHIPGVVIJZ-UHFFFAOYSA-L
  • dihydrate: InChI=1S/2ClH.2H2O.2O.U/h2*1H;2*1H2;;;/q;;;;;;+2/p-2
    Key: FGKUZTMTIQYKJZ-UHFFFAOYSA-L
  • trihydrate: InChI=1S/2ClH.3H2O.2O.U/h2*1H;3*1H2;;;/q;;;;;;;+2/p-2
    Key: BYLGCROXFJTSJF-UHFFFAOYSA-L
  • [Cl-].O=[U+2]=O.[Cl-]
  • hydrate: O.O=[U+2]=O.[Cl-].[Cl-]
  • dihydrate: O.O.O=[U+2]=O.[Cl-].[Cl-]
  • trihydrate: O.O.O.O=[U+2]=O.[Cl-].[Cl-]
Properties
UO2Cl2
Molar mass 340.90
Melting point Decomposes
Boiling point Decomposes
Solubility in other solvents 320 @ 18C
Hazards
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Uranyl chloride refers to inorganic compounds with the formula UO2Cl2(H2O)n where n = 0, 1, or 3. These are yellow-colored salts.

Synthesis and structures

Structure of the molecular complex uranyl chloride, trihydrate (UO2Cl2(H2O)3). Color scheme: red = O, green = U, Cl.[1]

The hydrates are obtained by dissolving uranyl sulfate or uranyl acetate in hydrochloric acid followed by crystallization from concentrated solutions. Depending on the method of drying, one obtains the mono- or the trihydrate. The monohydrate is described as a yellow, sulfur-like powder. It is very hygroscopic.[2] The trihydrate is greenish-yellow. Both hydrates are fluorescent solids that are highly soluble in water.[3]

The anhydrous material can be obtained by the reaction of oxygen with uranium tetrachloride:

UCl4 + O2 → UO2Cl2 + Cl2

In terms of structures, all three of these compounds feature the uranyl center (trans-UO22+) bound to five additional ligands, which can include (bridging) chloride, water, or another uranyl oxygen.[4][5]

Reactions

The aquo ligands can be replaced by a variety of donors, e.g. THF.[6]

Industrial importance

The company Indian Rare Earths Limited (IREL) has developed a process to extract uranium from the Western and Eastern coastal dune sands of India. After pre-processing with high-intensity magnetic separators and fine grinding, the mineral sands (known as monazite), are digested with caustic soda at about 120 °C (248 °F) and water. The hydroxide concentrate is further digested with concentrated hydrochloric acid to solubilise all hydroxides to form a feed solution composed of chlorides of uranium and other rare earth elements including thorium. The solution is subjected to liquid–liquid extraction with dual solvent systems to produce uranyl chloride and thorium oxalate. The crude uranyl chloride solution is subsequently refined to nuclear grade ammonium diuranate by a purification process involving precipitation and solvent extraction in a nitrate media.

References

  1. ↑ Debets, P. C. (1968). "The structures of uranyl chloride and its hydrates". Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry. 24 (3): 400–402. doi:10.1107/S056774086800244X.
  2. ↑ Hefley, Jack D.; Mathews, Daniel M.; Amis, Edward S. (1963). "Uranyl Chloride 1-Hydrate". Inorganic Syntheses. Inorganic Syntheses. Vol. 7. pp. 146–148. doi:10.1002/9780470132388.ch41. ISBN 9780470132388.
  3. ↑ F. Hein, S. Herzog (1963). "Uranyl Chloride". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2. NY, NY: Academic Press. p. 1439.
  4. ↑ Taylor, J. C.; Wilson, P. W. (1973). "The Structure of Anhydrous Uranyl Chloride by Powder Neutron Diffraction". Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry. 29 (5): 1073–1076. doi:10.1107/S0567740873003882.
  5. ↑ Leary, Joseph A.; Suttle, John F. (1957). "Uranyl Chloride". Inorganic Syntheses. Inorganic Syntheses. Vol. 5. pp. 148–150. doi:10.1002/9780470132364.ch41. ISBN 9780470132364.
  6. ↑ Wilkerson, Marianne P.; Burns, Carol J.; Paine, Robert T.; Scott, Brian L. (1999). "Synthesis and Crystal Structure of UO2Cl2(THF)3: A Simple Preparation of an Anhydrous Uranyl Reagent". Inorganic Chemistry. 38 (18): 4156–4158. doi:10.1021/ic990159g.
  • "Uranium". Encyclopædia Britannica. Vol. V27. 1911. p. 788.
  • Heyes, S.J. (1998). "Lanthanides & Actinides". Four Lectures in 2nd Year Inorganic Chemistry. Archived from the original on 23 September 2017. Retrieved 22 November 2011.
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