Uranyl fluoride

Uranyl fluoride (UO₂F₂), a compound of uranium, is an intermediate in the conversion of uranium hexafluoride UF₆ to a uranium oxide or metal form and is a direct product of the reaction of UF₆ with moisture in the air. It is very soluble in water. Uranyl fluoride also is hygroscopic and changes in color from brilliant orange to yellow after reacting with water. Uranyl fluoride is reported to be stable in air to 300 °C, above which slow decomposition to U₃O₈ occurs. When heated to decomposition, UO₂F₂ emits toxic fluorine fumes.

Uranyl fluoride

Names
IUPAC name Uranium fluoride oxide
Other names Uranium oxyfluoride
Identifiers
CAS Number	13536-84-0
ECHA InfoCard	100.033.529
CompTox Dashboard (EPA)	DTXSID9065528
Properties
Chemical formula	UO2F2
Molar mass	308.02 g/mol
Melting point	Decomposes @ 300 °C
Boiling point	Sublimes
Solubility in other solvents	VS
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

In accidental releases of UF₆, UO₂F₂, as a solid particulate compound, may deposit on the ground. The overall chemical reaction of this event can be represented as:

UF₆ + 2 H₂O → UO₂F₂ + 4 HF.

These reactions can take place whether the uranium hexafluoride is a solid or a gas, but will take place almost instantaneously when the UF₆ is in a gaseous state. The resulting hydrofluoric acid and the presence of additional water results in formation of solids (primarily hydrofluoric adducts of hydrated uranyl fluoride (${\displaystyle {\ce {UO2F2.{\mathit {n}}H2O}}}$).