Uranyl peroxide
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| __ U 6+ __ O 2− , O - | |||||||||||||||||||
| General | |||||||||||||||||||
| Surname | Uranyl peroxide | ||||||||||||||||||
| other names |
Uranium dioxide peroxide |
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| Ratio formula | UO 4 | ||||||||||||||||||
| Brief description |
light yellow solid |
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| properties | |||||||||||||||||||
| Molar mass | 302 g mol −1 | ||||||||||||||||||
| Physical state |
firmly |
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| boiling point |
Decomposition> 200 ° C |
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| solubility |
poorly soluble in water |
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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 peroxide is a chemical compound of uranium and oxygen and is one of the peroxides . It is contained in the mineral studtite in the form of its hydrate .
presentation
In general, uranyl peroxide can be obtained from a solution of uranium (VI) by adding a peroxide, usually hydrogen peroxide solution. The dihydrate is obtained from a boiling solution of uranyl nitrate with the addition of hydrogen peroxide and drying of the precipitate, while the trihydrate is precipitated from a solution of ammonium uranyl oxalate.
properties
Crystal structure
The crystal structure of the tetrahydrate consists of UO 2 2+ ions to which two water molecules and two peroxide ions O 2 2− are coordinated. The peroxide ions act as μ 2 ligands, which each connect two uranium atoms "edge-on". The additional crystal water molecules are bound to the uranyl peroxide chains by hydrogen bonds . The tetrahydrate is so far the only pure uranyl peroxide that has been structurally characterized by X-ray diffraction. However, using density functional theory , a structural model for the dihydrate could also be obtained that agrees well with previously published X-ray diffraction data.
use
More recently, the synthesis of peroxouranates has also been successful, which have complex cage structures that are similar in topology to fullerenes . These can be obtained from uranyl nitrate, hydrogen peroxide and an alkali hydroxide in aqueous solution; As a rule, organic molecules - for example amines - are also added. These presumably have a template function, similar to the representation of zeolites . Due to the synthesis conditions, these peroxouran compounds are not pure uranyl peroxides, since, depending on the synthesis method, they contain foreign ions such as Li + and organic molecules, which cannot always be detected using the method used to determine the structure.
In the potassium / uranyl / oxalate / peroxide system, similar structures can be built up step by step by varying the reaction conditions.
The more detailed investigation of the uranium / peroxide system in recent years is motivated by the observation that hydrogen peroxide can be formed by radiolysis in aqueous solution and knowledge of the chemical behavior of uranium and other actinides in the presence of peroxide for the storage of radioactive waste are relevant.
- Structures of some peroxouranates
Peroxouranate cluster with 50 uranium atoms
Dimers formed by peroxide bridges from uranyl ions in K 6 (H 2 O) 4 [(UO 2 ) 2 (O 2 ) (C 2 O 4 ) 4 ]
Pentagonal oxalate peroxouranate group in K 10 [(UO 2 ) (C 2 O 4 )] 5 (H 2 O) 13
safety instructions
Like all uranium compounds, peroxide is also radioactive. The specific activity of freshly produced uranyl peroxide from terrestrial natural uranium is 19930 Bq / g.
Individual evidence
- ↑ a b c Georg Brauer: uranium peroxide . In: Handbook of Preparative Inorganic Chemistry . Ferdinand Enke Verlag, Stuttgart 1954, p. 1081-1082 .
- ↑ James E. Boggs, Munzire El-Chehabi: "The Thermal Decomposition of Uranium Peroxide, UO 4 · 2H 2 O", in: J. Am. Chem. Soc. , 1957 , 79 (16), pp. 4258-4260; doi : 10.1021 / ja01573a003 .
- ↑ 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.
- ↑ Peter C. Burns, Karrie-Ann Hughes: Studtite, [(UO 2 ) (O 2 ) (H 2 O) 2 ] (H 2 O) 2 : The first structure of a peroxide mineral . In: American Mineralogist . tape 88 . Mineralogical Society of America , 2003, pp. 1165-1168 . ( Abstract ; PDF; 39 kB).
- ↑ Philippe F. Weck, Eunja Kim, Carlos F. Jové Colon, David C. Sassani: Structures of uranyl peroxide hydrates: a first-principles study of studtite and metastudtite . In: Dalton Transactions , 2012 , 41 , pp. 9748-9752 ( doi : 10.1039 / c2dt31242e ).
- ↑ a b Tori Z. Forbes, J. Gregory McAlpin, Rachel Murphy, Peter C. Burns: "Metal-Oxygen Isopolyhedra Assembled into Fullerene Topologies", in: Angew. Chem. Int. Ed. , 2008 , 47 , pp. 2824-2827; doi : 10.1002 / anie.200705563 .
- ↑ a b c Ginger E. Sigmon, Jie Ling, Daniel K. Unruh, Laura Moore-Shay, Matthew Ward, Brittany Weaver, Peter C. Burns: "Uranyl-Peroxide Interactions Favor Nanocluster Self-Assembly", in: J. Am . Chem. Soc. , 2009 , 131 , pp. 16648-16649; doi : 10.1021 / ja907837u ; PMID 19919139 .
- ^ Sara Nilsson, Mats Jonsson: "H 2 O 2 and radiation induced dissolution of UO 2 and SIMFUEL pellets", in: Journal of Nuclear Materials , 2011 , 410 (1-3) , pp. 89-93; doi : 10.1016 / j.jnucmat.2011.01.020 .
literature
- 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 .