sulfur dichloride

Sulfur dichloride
General
Systematic name	Sulfur(II) chloride
Other names	sulfur dichloride sulfur chloride dichlorosulfane;
Molecular formula	Cl2S
SMILES	ClSCl
Molar mass	102.97 g mol−1
Appearance	red liquid at STP
CAS number	[10545-99-0]
Properties
Density and phase	1.621 g cm−3, liquid
Solubility in water	hydrolysis
Other solvents	benzene, chlorocarbons
Melting point	−121.0 °C
Boiling point	59 °C
Structure
geometry	C2v
Dipole moment	? D
Hazards
MSDS	External MSDS
Main hazards	corrosive
NFPA 704
R/S statement	R: R14; R34; R37; N; R50 S: ?
RTECS number	WS4500000
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	Sulfur tetrafluoride, SF4 Sulfuryl chloride, SO2Cl2 Thionyl chloride, SOCl2 Disulfur dichloride, S2Cl2
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Sulfur dichloride is the chemical compound with the formula SCl₂. This cherry-red liquid is the simplest and one of two common sulfur chlorides. It is used as a precursor to organosulfur compounds.^[1]

Chlorination of sulfur

SCl₂ is produced by the chlorination of either elemental sulfur. The process occurs in a series of steps, some of which are:

S₈ + 4Cl₂ → 4S₂Cl₂; ΔH = −58.2 kJ/mol

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

The addition of Cl₂ to S₂Cl₂ has been proposed 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.

Disulfur dichloride, S₂Cl₂, is the most common impurity in SCl₂. Separation of SCl₂ from S₂Cl₂ is possible via distillation with PCl₃ to form an azeotrope of 99% purity

Use of SCl₂ in chemical synthesis

• SCl₂ is used in organic synthesis]]. It adds to alkenes to give chloride-substituted thioethers. Illustrative applications are its addition to 1,5-cyclooctadiene to give a bicyclic thioether^[2] and ethylene to give sulfur mustard S(CH₂CH₂Cl)₂.^[3]

SCl₂ is also a precursor to several inorganic sulfur compounds. Treatment with fluoride salts gives SF₄. Reaction with ammonia affords sulfur nitrides related to S₄N₄. With H₂S, SCl₂ reacts to give "higher" sulfanes such as S₃H₂.

Safety considerations

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

References

1. ^ Schmidt, M.; Siebert, W. "Sulphur" Comprehensive Inorganic Chemistry Vol. 2, ed. A.F. Trotman-Dickenson. 1973.
2. ^ Bishop, R. "9-Thiabicyclo[3.3.1]nonane-2,6-dione" Organic Syntheses, Collected Volume 9, p.692 (1998). http://www.orgsyn.org/orgsyn/pdfs/CV9P0692.pdf
3. ^ R. J. Cremlyn “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). ISBN 0 471 95512 4.

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