Sulfur dichloride
General
Systematic name	Sulfur(II) chloride
Other names	sulfur dichloride
Molecular formula	SCl2
SMILES	?
Molar mass	102.97 g/mol
Appearance	red liquid
CAS number	*
Properties
Density and phase	1.621 g/cm3
Solubility in water	decomp with loss of HCl
Other solvents	benzene, chlorocarbons
Melting point	–121.0 °C (? K)
Boiling point	59 °C (? K)
Structure
Coordination geometry	C2v
Dipole moment	? D
Hazards
MSDS	External MSDS
Main hazards	?
NFPA 704
R/S statement	R: ? S: ?
RTECS number	?
Supplementary data page
Structure and properties	n, 1.5570
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related compounds	SF4 SO2Cl2 S2Cl2
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Chemical infobox

Sulfur dichloride is SCl₂. This cherry-red liquid (room temperature) is produced by the chlorination of either elemental sulfur or S₂Cl₂ , disulphur dichloride (or sulfur monochloride). Separation of SCl₂ from S₂Cl₂ is possible via distillation with PCl₃ to form an azeotrope of 99% purity. SCl₂ into the monochloride

Chlorination of sulfur

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The chlorination of sulfur occurs in a series of steps, some of which are:

S₈ + 4 Cl₂ → 4 S₂Cl₂ ΔH = -58.2 kJ/mol

S₂Cl₂ + Cl₂ → 2 SCl₂ ΔH = -40.6 kJ/mol

The addition of Cl₂ to S₂Cl₂ is considered to proceed via a mixed valence intermediate Cl₃S-SCl. SCl₂ undergoes even further chlorination to give SCl₄, but this species is unstable at near room temperature. It is likely that several S_xCl₂ exist where x >2.

Use of SCl₂ in chemical synthesis

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• SCl₂ is occasionally useful in organic synthesis, an illustrative application is its addition to 1,5-cyclooctadiene to give a bicyclic thioether. In an infamous reaction, SCl₂ adds ethylene to give mustard gas (which is not a gas).
• SCl₂ is a precursor to SF₄.
• SCl₂ is a key reagent in the preparation of S-N compounds related to S₄N₄.
• SCl₂ reacts with H₂S to give "higher" sulfanes such as S₃H₂.

Safety considerations

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SCl₂ hydrolyzes potentially dangerously with release of HCl. Old samples contain Cl₂.

References

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M. Schmidt, W. Siebert "Sulphur" Comprehensive Inorganic Chemistry Vol. 2, ed. A.F. Trotman-Dickenson. 1973.

External links

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Chlorides | Sulfur compounds

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