Thiophosgene

Thiophosgene

Names
IUPAC name Carbonothioyl dichloride
Other names Thiophosgene; Thiocarbonyl chloride; Carbonothioic dichloride
Identifiers
CAS Number	463-71-8 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:29366 Y
ChemSpider	9645 Y
ECHA InfoCard	100.006.675
PubChem	10040
RTECS number	XN2450000
UNII	067FQP576P Y
InChI InChI=1S/CCl2S/c2-1(3)4 Y Key: ZWZVWGITAAIFPS-UHFFFAOYSA-N Y InChI=1/CCl2S/c2-1(3)4 Key: ZWZVWGITAAIFPS-UHFFFAOYAH
SMILES ClC(Cl)=S
Properties
Chemical formula	CSCl2
Molar mass	114.98 g/mol
Appearance	Red liquid
Density	1.50 g/cm3
Boiling point	70 to 75 °C (158 to 167 °F; 343 to 348 K)
Solubility in water	Decomposition
Solubility in other solvents	polar organic solvents rxn with amines and alcohols
Refractive index (nD)	1.558
Structure
Molecular shape	planar, sp2, C2v
Hazards
Main hazards	Highly toxic
Flash point	62 °C (144 °F; 335 K)
Related compounds
Related compounds	Phosgene Thiocarbonyl fluoride Thiocarbonyl bromide Sulfur dichloride thionyl chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Thiophosgene is a red liquid with the formula CSCl₂. It is a molecule with trigonal planar geometry. There are two reactive C–Cl bonds that allow it to be used in diverse organic syntheses.^[1]

Preparation of CSCl₂

CSCl₂ is prepared in a two-step process from carbon disulfide. In the first step, carbon disulfide is chlorinated to give trichloromethanesulfenyl chloride (perchloromethyl mercaptan), CCl₃SCl:

CS₂ + 3 Cl₂ → CCl₃SCl + S₂Cl₂

The chlorination must be controlled as excess chlorine converts trichloromethanesulfenyl chloride into carbon tetrachloride. Steam distillation separates the trichloromethanesulfenyl chloride, a rare sulfenyl chloride, and hydrolyzes the sulfur monochloride. Reduction of trichloromethanesulfenyl chloride produces thiophosgene:

CCl₃SCl + M → CSCl₂ + MCl₂

Typically, tin is used for the reducing agent M.^[2]

Uses of CSCl₂

CSCl₂ is mainly used to prepare compounds with the connectivity CSX₂ where X = OR, NHR.^[3] Such reactions proceed via intermediate such as CSClX. Under certain conditions, one can convert primary amines into isothiocyanates. CSCl₂ also serves as a dienophile to give, after reduction 5-thiacyclohexene derivatives. Thiophosgene is also known as the appropriate reagent in Corey-Winter synthesis for stereospecific conversion of 1,2-diols into olefins.^[4]

Safety considerations

CSCl₂ is considered highly toxic.

References

Further reading

• Holleman, A. F.; Wiberg, E. (2001), Inorganic Chemistry, San Diego: Academic Press, ISBN 0-12-352651-5