Uranium tetrafluoride

Uranium tetrafluoride
Names
	IUPAC names Uranium(IV) fluoride; Uranium tetrafluoride
Identifiers
CAS Number	10049-14-6 ;
3D model (JSmol)	Interactive image ;
ChemSpider	14676181 ;
ECHA InfoCard	100.030.142
EC Number	233-170-1;
PubChem CID	61461 ;
UNII	PJ46VTD8B2 ;
CompTox Dashboard (EPA)	DTXSID30892258 ;
	InChI InChI=1S/4FH.2U/h41H;;/q;;;;2+2/p-4 Key: CWWZGQYYTNZESQ-UHFFFAOYSA-J ; InChI=1/4FH.2U/h41H;;/q;;;;2+2/p-4 Key: CWWZGQYYTNZESQ-XBHQNQODAW;
	SMILES F[U](F)(F)F;
Properties
Chemical formula	UF4
Molar mass	314.02 g/mol
Appearance	Green crystalline solid
Density	6.70 g/cm3, solid
Melting point	1,036 °C (1,897 °F; 1,309 K)
Boiling point	1,417 °C (2,583 °F; 1,690 K)
Solubility in water	Insoluble
Structure
Crystal structure	Monoclinic, mS60
Space group	C2/c, No. 15
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H300, H330, H373, H411
Flash point	Non-flammable
Safety data sheet (SDS)	External MSDS
Related compounds
Other anions	Uranium(IV) chloride ; Uranium(IV) bromide ; Uranium(IV) iodide ; Uranium dioxide
Other cations	Praseodymium(IV) fluoride ; Thorium(IV) fluoride ; Protactinium(IV) fluoride ; Neptunium(IV) fluoride ; Plutonium(IV) fluoride
Related compounds	Uranium hexafluoride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Last updated October 04, 2024

Uranium tetrafluoride is the inorganic compound with the formula UF₄. It is a green solid with an insignificant vapor pressure and low solubility in water. Uranium in its tetravalent (uranous) state is important in various technological processes. In the uranium refining industry it is known as green salt.^[1]

Production

UF₄ is prepared from UO₂ in a fluidized bed by reaction with Hydrogen fluoride. The UO₂ is derived from mining operations. Around 60,000 tonnes are prepared in this way annually. A common impurity is UO₂F₂. UF4 is susceptible to hydrolysis as well.^[1]

UF₄ is formed by the reaction of UF₆ with hydrogen gas in a vertical tube-type reactor. The bulk density of UF₄ varies from about 2.0 g/cm³ to about 4.5 g/cm³ depending on the production process and the properties of the starting uranium compounds.

A molten salt reactor design, a type of nuclear reactor where the working fluid is a molten salt, would use UF₄ as the core material. UF₄ is generally chosen over related compounds because of the usefulness of the elements without isotope separation, better neutron economy and moderating efficiency, lower vapor pressure and better chemical stability.

Reactions

Uranium tetrafluoride reacts stepwise with fluorine, first to give uranium pentafluoride and then volatile UF₆:

2 UF₄ + F₂ → 2 UF₅

2 UF₅ + F₂ → 2 UF₆

UF₄ is reduced by magnesium to give the metal:^[2]

UF₄ + 2 Mg → U + 2 MgF₂

UF₄ reacts slowly with moisture at ambient temperature, forming UO₂ and HF.

Structure

Like most binary metal fluorides, UF₄ is a dense highly crosslinked inorganic polymer. As established by X-ray crystallography, the U centres are eight-coordinate with square antiprismatic coordination spheres. The fluoride centres are doubly bridging.^[2]^[3]

Safety

Like all uranium salts, UF₄ is toxic and thus harmful by inhalation, ingestion, and through skin contact.

References of historical interest

Booth, H. S.; Krasny-Ergen, W.; Heath, R. E. (1946). "Uranium Tetrafluoride". Journal of the American Chemical Society. 68 (10): 1969. doi:10.1021/ja01214a028.

Related Research Articles

<span class="mw-page-title-main">Uranium hexafluoride</span> Chemical compound

Uranium hexafluoride, sometimes called hex, is an inorganic compound with the formula UF₆. Uranium hexafluoride is a volatile, toxic white solid that is used in the process of enriching uranium, which produces fuel for nuclear reactors and nuclear weapons.

Tungsten(VI) fluoride, also known as tungsten hexafluoride, is an inorganic compound with the formula WF₆. It is a toxic, corrosive, colorless gas, with a density of about 13 kg/m³ (22 lb/cu yd). It is the only known gaseous transition metal compound and the densest known gas under standard ambient temperature and pressure. WF₆ is commonly used by the semiconductor industry to form tungsten films, through the process of chemical vapor deposition. This layer is used in a low-resistivity metallic "interconnect". It is one of seventeen known binary hexafluorides.

<span class="mw-page-title-main">Beryllium fluoride</span> Chemical compound

Beryllium fluoride is the inorganic compound with the formula BeF₂. This white solid is the principal precursor for the manufacture of beryllium metal. Its structure resembles that of quartz, but BeF₂ is highly soluble in water.

<span class="mw-page-title-main">Bromine pentafluoride</span> Chemical compound

Bromine pentafluoride, BrF₅, is an interhalogen compound and a fluoride of bromine. It is a strong fluorinating agent.

<span class="mw-page-title-main">Lithium fluoride</span> Chemical compound

Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid that transitions to white with decreasing crystal size. Its structure is analogous to that of sodium chloride, but it is much less soluble in water. It is mainly used as a component of molten salts. Partly because Li and F are both light elements, and partly because F₂ is highly reactive, formation of LiF from the elements releases one of the highest energies per mass of reactants, second only to that of BeO.

Hydrogen fluoride (fluorane) is an inorganic compound with chemical formula HF. It is a very poisonous, colorless gas or liquid that dissolves in water to yield an aqueous solution termed hydrofluoric acid. It is the principal industrial source of fluorine, often in the form of hydrofluoric acid, and is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers, e.g. polytetrafluoroethylene (PTFE). HF is also widely used in the petrochemical industry as a component of superacids. Due to strong and extensive hydrogen bonding, it boils at near room temperature, much higher than other hydrogen halides.

Uranium trioxide (UO₃), also called uranyl oxide, uranium(VI) oxide, and uranic oxide, is the hexavalent oxide of uranium. The solid may be obtained by heating uranyl nitrate to 400 °C. Its most commonly encountered polymorph is amorphous UO₃.

<span class="mw-page-title-main">Uranium pentafluoride</span> Chemical compound

Uranium pentafluoride is the inorganic compound with the chemical formula UF₅. It is a pale yellow paramagnetic solid. The compound has attracted interest because it is related to uranium hexafluoride, which is widely used to produce uranium fuel. It crystallizes in two polymorphs, called α- and β-UF₅.

Zirconium(IV) fluoride describes members of a family inorganic compounds with the formula ZrF₄(H₂O)_x. All are colorless, diamagnetic solids. Anhydrous Zirconium(IV) fluoride is a component of ZBLAN fluoride glass.

<span class="mw-page-title-main">Technetium hexafluoride</span> Chemical compound

Technetium hexafluoride or technetium(VI) fluoride (TcF₆) is a yellow inorganic compound with a low melting point. It was first identified in 1961. In this compound, technetium has an oxidation state of +6, the highest oxidation state found in the technetium halides. In this respect, technetium differs from rhenium, which forms a heptafluoride, ReF₇. Technetium hexafluoride occurs as an impurity in uranium hexafluoride, as technetium is a fission product of uranium (spontaneous fission in natural uranium, possible contamination from induced fission inside the reactor in reprocessed uranium). The fact that the boiling point of the hexafluorides of uranium and technetium are very close to each other presents a problem in using fluoride volatility in nuclear reprocessing.

Uranium compounds are compounds formed by the element uranium (U). Although uranium is a radioactive actinide, its compounds are well studied due to its long half-life and its applications. It usually forms in the +4 and +6 oxidation states, although it can also form in other oxidation states.

<span class="mw-page-title-main">Manganese(IV) fluoride</span> Chemical compound

Manganese tetrafluoride, MnF₄, is the highest fluoride of manganese. It is a powerful oxidizing agent and is used as a means of purifying elemental fluorine.

<span class="mw-page-title-main">Uranium nitrides</span> Chemical compound

Uranium nitrides is any of a family of several ceramic materials: uranium mononitride (UN), uranium sesquinitride (U₂N₃) and uranium dinitride (UN₂). The word nitride refers to the −3 oxidation state of the nitrogen bound to the uranium.

The Fernald Feed Materials Production Center is a Superfund site located within Crosby Township in Hamilton County, Ohio, as well as Ross Township in Butler County, Ohio, in the United States. It was a uranium processing facility located near the rural town of New Baltimore, about 20 miles (32 km) northwest of Cincinnati, which fabricated uranium fuel cores for the U.S. nuclear weapons production complex from 1951 to 1989. During that time, the plant produced 170,000 metric tons uranium (MTU) of metal products and 35,000 MTU of intermediate compounds, such as uranium trioxide and uranium tetrafluoride.

Plutonium hexafluoride is the highest fluoride of plutonium, and is of interest for laser enrichment of plutonium, in particular for the production of pure plutonium-239 from irradiated uranium. This isotope of plutonium is needed to avoid premature ignition of low-mass nuclear weapon designs by neutrons produced by spontaneous fission of plutonium-240.

<span class="mw-page-title-main">FLiBe</span> Chemical compound

FLiBe is the name of a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride. It is both a nuclear reactor coolant and solvent for fertile or fissile material. It served both purposes in the Molten-Salt Reactor Experiment (MSRE) at the Oak Ridge National Laboratory.

Neptunium(VI) fluoride (NpF₆) is the highest fluoride of neptunium, it is also one of seventeen known binary hexafluorides. It is a volatile orange crystalline solid. It is relatively hard to handle, being very corrosive, volatile and radioactive. Neptunium hexafluoride is stable in dry air but reacts vigorously with water.

Depleted uranium hexafluoride (DUHF; also referred to as depleted uranium tails, depleted uranium tailings or DUF₆) is a byproduct of the processing of uranium hexafluoride into enriched uranium. It is one of the chemical forms of depleted uranium (up to 73-75%), along with depleted triuranium octoxide (up to 25%) and depleted uranium metal (up to 2%). DUHF is 1.7 times less radioactive than uranium hexafluoride and natural uranium.

Praseodymium(IV) fluoride (also praseodymium tetrafluoride) is a binary inorganic compound, a highly oxidised metal salt of praseodymium and fluoride with the chemical formula PrF₄.

Protactinium tetrafluoride is a binary inorganic compound of protactinium metal and fluorine with the chemical formula PaF₄.

References

1 2 Peehs, Martin; Walter, Thomas; Walter, Sabine; Zemek, Martin (2007). "Uranium, Uranium Alloys, and Uranium Compounds". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a27_281.pub2. ISBN 978-3527306732.
1 2 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
↑ Kern, S.; Hayward, J.; Roberts, S.; Richardson, J. W.; Rotella, F. J.; Soderholm, L.; Cort, B.; Tinkle, M.; West, M.; Hoisington, D.; Lander, G. A. (1994). "Temperature Variation of the Structural Parameters in Actinide Tetrafluorides". The Journal of Chemical Physics. 101 (11): 9333–9337. Bibcode:1994JChPh.101.9333K. doi:10.1063/1.467963.

External links

"Uranium Tetrafluoride". Appendix A of the PEIS (DOE/EIS-0269). Argonne National Laboratory. Archived from the original on 30 January 2016. Retrieved 22 November 2011.

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[Ullmann-1] 1 2 Peehs, Martin; Walter, Thomas; Walter, Sabine; Zemek, Martin (2007). "Uranium, Uranium Alloys, and Uranium Compounds". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a27_281.pub2. ISBN 978-3527306732.

[G&E-2] 1 2 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

[3] Kern, S.; Hayward, J.; Roberts, S.; Richardson, J. W.; Rotella, F. J.; Soderholm, L.; Cort, B.; Tinkle, M.; West, M.; Hoisington, D.; Lander, G. A. (1994). "Temperature Variation of the Structural Parameters in Actinide Tetrafluorides". The Journal of Chemical Physics. 101 (11): 9333–9337. Bibcode:1994JChPh.101.9333K. doi:10.1063/1.467963.

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