Sulfur dichloride
IUPAC name	Sulfur dichloride Sulfur(II) chloride Dichlorosulfane
Other names	Sulfur chloride
Identifiers
CAS number	10545-99-0 Y
EC number	234-129-0
UN number	1828
RTECS number	WS4500000
SMILES	ClSCl
Properties
Molecular formula	SCl2
Molar mass	102.97 g mol−1
Appearance	red liquid with pungent odour
Density	1.621 g cm−3, liquid
Melting point	−121.0 °C (152.15 K)
Boiling point	59 °C (332.15 K) (decomp.)
Solubility in water	hydrolysis
Refractive index (nD)	1.5570
Structure
Coordination geometry	C2v
Molecular shape	Bent
Hazards
MSDS	ICSC 1661
EU Index	016-013-00-X
EU classification	Corrosive (C) Irritant (Xi) Dangerous for the environment (N)
R-phrases	R14, R34, R37, R50
S-phrases	(S1/2), S26, S45, S61
NFPA 704	1 3 2 W
Autoignition temperature	234 °C
Related compounds
Related	Disulfur dichloride Thionyl chloride Sulfuryl chloride
Related compounds	Sulfur tetrafluoride Sulfur hexafluoride Disulfur dibromide
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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

[edit] Chlorination of sulfur

SCl₂ is produced by the chlorination of either elemental sulfur or disulfur dichloride. The process 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 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

[edit] 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 "lower" sulfanes such as S₃H₂.

[edit] Safety considerations

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

[edit] References