Thiophosgene

Thiophosgene
Thiophosgene	Thiophosgene
Names
	IUPAC name Carbonothioyl dichloride
	Other names Thiophosgene; Thiocarbonyl chloride; Carbonothioic dichloride
Identifiers
CAS Number	463-71-8 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:29366 ;
ChemSpider	9645 ;
ECHA InfoCard	100.006.675
PubChem CID	10040;
RTECS number	XN2450000;
UNII	067FQP576P ;
CompTox Dashboard (EPA)	DTXSID2060046 ;
	InChI InChI=1S/CCl2S/c2-1(3)4 Key: ZWZVWGITAAIFPS-UHFFFAOYSA-N ; InChI=1/CCl2S/c2-1(3)4 Key: ZWZVWGITAAIFPS-UHFFFAOYAH;
	SMILES ClC(Cl)=S;
Properties
Chemical formula	CSCl2
Molar mass	114.97 g·mol−1
Appearance	Red liquid
Odor	Persistent, choking odor
Density	1.50 g/cm3
Boiling point	70 to 75 °C (158 to 167 °F; 343 to 348 K)
Solubility in water	Decomposes
Solubility in other solvents	Reacts with amines and alcohols, soluble in polar organic solvents
Magnetic susceptibility (χ)	-50.6·10−6 cm3/mol
Refractive index (nD)	1.558
Structure
Molecular shape	planar, sp2, C2v
Hazards
	Occupational safety and health (OHS/OSH):
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). verify (what is ?) 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

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 disulfur dichloride. Reduction of trichloromethanesulfenyl chloride produces thiophosgene:

CCl₃SCl + M → CSCl₂ + MCl₂

Tin^[2] and dihydroanthracene^[3] have been used for the reducing agents.

Reactions

CSCl₂ is mainly used to prepare compounds with the connectivity CSX₂ where X = OR, NHR.^[4] 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 alkenes.^[5]

It forms a head-to-tail dimer upon irradiation with UV light:^[6]

2 CSCl₂ → S₂(CCl₂)₂

Unlike thiophosgene monomer, a red liquid, the photodimer, an example of a 1,3-dithietane, is a colourless solid.

Thisphosgene decomposes at 200 °C or above to form carbon disulfide and carbon tetrachloride.^[7] It has also been observed decomposing to hydrogen sulfide, hydrogen chloride, and carbonyl sulfide gases via contact with human tissue.^[8]^{[failed verification]}

Toxicology and safety

CSCl₂ is considered highly toxic. Inhalation of the substance can cause irritation of respiratory system, burns, delayed pulmonary edema and death.^[9]

References

^ Manchiu D. S. Lay, Mitchell W. Sauerhoff And Donald R. Saunders "Carbon Disulfide" in Ullmann's Encyclopedia Of Industrial Chemistry, 2000, Wiley-VCH, Weinheim. doi:10.1002/14356007.a05_185
^ Dyson, G. M. (1926). "Thiophosgene". Organic Syntheses. 6: 86. doi:10.15227/orgsyn.006.0086.
^ K. T. Potts, C. Sapino (1972). "Thiocarbonyl halides". In S. Patai (ed.). Acyl Halides. PATAI'S Chemistry of Functional Groups. pp. 349–380. doi:10.1002/9780470771273.ch11. ISBN 978-0-470-77127-3.
^ Pascual, Roxana Martinez "Thiophosgene" Synlett 2015, vol. 26, pp. 1776-1777.doi:10.1055/s-0034-1380659
^ Sharma, S. (1978). "Thiophosgene in Organic Synthesis". Synthesis. 1978 (11): 803–820. doi:10.1055/s-1978-24896.
^ B. Krebs H. Beyer (1969). "Die Kristall- und Molekelstruktur des dimeren Thiophosgens". Z. Anorg. Allg. Chem. 365 (3–4): 199–210. doi:10.1002/zaac.19693650315.
^ U.S. Coast Guard, Department of Transportation (1999). CHRIS - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office — via Cameo Chemicals. As cited in "Thiophosgene" PubChem compound record.
^ "Thiophosgene".
^ US National Library of Medicine (2020). Hazardous Substances Databank entry, as summarized on "Thiophosgene" PubChem compound record.