sulfur hexafluoride

Sulfur(VI) fluoride Other names Sulfur fluoride

Elagas™

Esaflon™ Identifiers CAS number 2551-62-4 UN number 1080 RTECS number WS4900000 SMILES [show] FS(F)(F)(F)(F)F Properties Molecular formula SF6 Molar mass 146.06 g/mol Appearance colorless, odorless gas Density 6.164 g/L (gas, 1 bar: ~5.1 times denser than air)

1.329 g/ml (liquid, 25 °C)

2.510 g/cm3 (solid, -50.8 °C) Boiling point

-64 °C (209 K) (subl.)

decomp. at ca. 500 °C (773 K) Solubility in water low Structure Coordination

geometry octahedral (Oh) Dipole moment zero Hazards MSDS External MSDS EU Index Not listed Main hazards Asphyxiant in high concentrations, no odour warning Related compounds Other cations Selenium hexafluoride

Tellurium hexafluoride Related sulfur fluorides Disulfur difluoride

Sulfur difluoride

Sulfur tetrafluoride

Disulfur decafluoride Related compounds Sulfuryl fluoride Except where noted otherwise, data are given for

materials in their standard state

(at 25 °C, 100 kPa)

Infobox references

Sulfur hexafluoride is an inorganic compound with the formula SF6. It is a colorless, odorless, non-toxic and non-flammable gas (under standard conditions). SF6 has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom. It is a hypervalent molecule. Typical for a nonpolar gas, it is poorly soluble in water but soluble in nonpolar organic solvents. It is generally transported as a liquified compressed gas. It has a density of 6.13 g/L at sea level conditions, which is considerably higher than the density of air. Contents [hide] 1 Synthesis and chemistry 2 Applications 2.1 Dielectric medium 2.2 Medical use 2.3 Tracer compound 2.4 Other uses 3 Greenhouse gas 4 Physiological effects and precautions 5 Other Properties 6 References 7 Further reading 8 See also 9 External links //

Synthesis and chemistry

SF6 can be prepared from the elements through exposure of S8 to F2. This is also the method used by the discoverers Henri Moissan and Paul Lebeau in 1901. Some other sulfur fluorides are cogenerated, but these are removed by heating the mixture to disproportionate any S2F10 and then scrubbing the product with NaOH to destroy remaining SF4.

There is virtually no reaction chemistry for SF6. It does not react with molten sodium, but reacts exothermically with lithium.

Starting from SF4, one can prepare SF5Cl, which is structurally related to SF6. The monochloride is, however, a strong oxidant and readily hydrolyzed to sulfate.

Applications

Of the 8,000 tons produced per year, most of the SF6 goes into three applications: firstly as a gaseous dielectric medium or other use in the electrical industry, which accounts for 6,000 tons; secondly as an inert gas for the casting of magnesium; and thirdly as an inert filling for windows.

Dielectric medium

SF6 is used in the electrical industry as a gaseous dielectric medium for high-voltage (35