Uranyl chloride
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| General | |||||||||||||||||||
| Surname | Uranyl chloride | ||||||||||||||||||
| other names |
Dichlorodioxyuran |
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| Molecular formula | (UO 2 ) Cl 2 | ||||||||||||||||||
| Brief description |
yellow, fluorescent crystals |
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| properties | |||||||||||||||||||
| Molar mass | 340.90 g mol −1 | ||||||||||||||||||
| Physical state |
firmly |
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| solubility |
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| Hazard and safety information | |||||||||||||||||||
 Radioactive |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||||||||
Uranyl chloride , (UO 2 ) Cl 2 is an unstable, light yellow chemical compound of uranium. It forms large sand-like crystals.
Extraction and presentation
The connection is formed when chlorine gas is passed over red-hot uranium dioxide :
or as a compound containing water of crystallization, if uranium trioxide is dissolved in hydrochloric acid and the solution is then concentrated in vacuo until it crystallizes:
An aqueous solution of the compound can be obtained by treating a solution of uranyl sulfate with a barium chloride solution and separating the barium sulfate which precipitates :
properties
The hygroscopic uranyl chloride and its two hydrates ((UO 2 ) Cl 2 · H 2 O / (UO 2 ) Cl 2 · 3 H 2 O) decompose under the action of light, which was determined by Adolph Ferdinand Gehlen in 1804 . This photosensitivity at times attracted scientific attention and aroused numerous unsuccessful efforts to use the salts for new photographic applications. Like many other uranium compounds , uranyl chloride shows fluorescence under ultraviolet light , but it is weak compared to other uranyl salts.
Crystal structure
The crystal structure of solvent-free uranyl chloride was first determined by Debets in 1968. In the crystal structure, the cation-cation interaction can be seen, which is characteristic of uranyl compounds. One uranyl unit coordinates an oxygen atom of another uranyl unit in the equatorial position, resulting in a three-dimensional network. The chlorine atoms also bridge two neighboring uranyl units in the equatorial plane.
Industrial importance
The company Indian Rare Earths Limited (IREL) has developed a way of uranium from the eastern and western coastal dunes of India to win. After pre-processing with strong magnetic separators and pulverization, the mineral-containing sands ( monazites ) are split under pressure with sodium hydroxide and water at around 120 ° C. Concentrated hydrochloric acid is then added to the hydroxide solution to convert the hydroxides into a saturated solution of uranium chloride and other rare earth chloride (including thorium ). The solvent is then extracted from the solution, whereby uranyl chloride and thorium oxalate are formed. The impure uranyl chloride solution is then refined to nuclear purity by precipitation and extraction of the foreign substances in nitrate solution .
Health and environmental hazards
Uranyl chloride is highly toxic when inhaled and swallowed. In addition, there is a risk of accumulation in the human body, especially in the liver and kidneys . It is also toxic to aquatic organisms and can cause long-term damage to the aquatic world. Like all uranium compounds, it is radioactive . The activity depends on the isotopic composition of the uranium.
Web links
- Nuclear Chemistry ( Memento of 14 September 2008 at the Internet Archive ) (Engl.)
literature
- TK Mukherjee: The Role of IREL in the Indian Nuclear Energy Program . In: An International Journal of Nuclear Power . tape 18 , no. 2-3 , 2004, pp. 81-83 ( PDF ).
- Ingmar Grenthe, Janusz Drożdżynński, Takeo Fujino, Edgar C. Buck, Thomas E. Albrecht-Schmitt, Stephen F. Wolf: Uranium. In: Lester R. Morss, Norman M. Edelstein, Jean Fuger (Eds.): The Chemistry of the Actinide and Transactinide Elements. Springer, Dordrecht 2006, ISBN 1-4020-3555-1 , pp. 253-698; doi : 10.1007 / 1-4020-3598-5_5 ( PDF ).
Individual evidence
- ↑ N. Kumar, Dennis G. Tuck: The direct electrochemical synthesis of neutral and anionic halogen complexes of uranium (IV) and uranium (VI) . In: Inorganica Chimica Acta . tape 95 , no. 4 , 1984, pp. 211-215 , doi : 10.1016 / S0020-1693 (00) 87469-1 .
- ↑ a b B. S. Satyanarayana: The fluorescence of the uranyl compounds and the raman spectrum of the uranyl ion . In: Proceedings Mathematical Sciences . tape 15 , no. 5 , 1942, pp. 414-416 , doi : 10.1007 / BF03046037 .
- ↑ a b c Georg Brauer: Uranyl chloride . In: Handbook of Preparative Inorganic Chemistry . Ferdinand Enke Verlag, Stuttgart 1954, p. 1076 .
- ↑ Afif M. Seyam: Observations on the reaction of uranium tetrachloride and dichlorodioxouranium (VI) with lithium alkyls . In: Inorganica Chimica Acta . tape 10 , no. 2 , 1985, pp. 123-126 , doi : 10.1016 / S0020-1693 (00) 84567-3 .
- ↑ Entry on uranium compounds in the GESTIS substance database of the IFA , accessed on February 1, 2016 (JavaScript required)
- ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry uranium compounds with the exception of those specified elsewhere in this Annex in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) , accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
- ↑ The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling.
- ↑ Joseph A. Leary and John F. Suttle: Uranyl chloride [Uranium (VI) Dioxydichloride] . In: Therald Moeller (Ed.): Inorganic Syntheses . tape 5 . McGraw-Hill, Inc., 1957, pp. 148-150 (English).
- ↑ PC Debets: The Structures of Uranyl Chloride and its Hydrates In: Acta Crystallographica, Section B24 . 1968, p. 400 .