9856. Uranium Hexafluoride

Nomenclature

CAS number: 7783-81-5
F6U; mol wt 352.02.
F 32.38%, U 67.62%.
UF6.

Description and references

Prepd by the action of fluorine on uranium metal or carbide; on uranium pentachloride; on uranium tetrafluoride; on triuranium octaoxide in the presence of carbon. It appears that all uranium compds when heated with fluorine to a sufficiently high temp give UF6: National Nuclear Energy Series VIII-5, J. J. Katz, E. Rabinowitch, The Chemistry of Uranium, part I (New York, 1951) pp 396-449.

Properties

Volatile, white monoclinic cryst solid. d420.7 5.09. d70 (liq) 3.595. mp 64.8°. Sublimes at 56.5°. Critical temp 230.2°, crit pressure 45.5 atm: Oliver et al., J. Am. Chem. Soc. 75, 2827 (1953). Reacts vigorously with water, forming mainly UO2F2 and HF. Sol in liquid chlorine and bromine. Dissolves in nitrobenzene to give a dark red soln fuming in air. Sol in carbon tetrachloride, chloroform, and sym-tetrachloroethane, Cl2CHCHCl2, which forms the most stable soln, extensive reaction occurring only after several days at room temp. Sol in fluorocarbons (C6F12 or C7F16) without reaction. Best handled in copper apparatus.