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
Organic Syntheses
Organic Syntheses is a scientific journal that since 1921 has provided the chemistry community with annual collections of detailed and checked procedures for the organic synthesis of organic compounds. The journal is peer reviewed...


Synthesis of CSCl2

CSCl2 is prepared in a two-step process from carbon disulfide
Carbon disulfide
Carbon disulfide is a colorless volatile liquid with the formula CS2. The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical non-polar solvent...

. In the first step, carbon disulfide is chlorinated to give trichloromethanesulfenyl chloride, CCl3SCl:
CS2 + 3 Cl2 → CCl3SCl + S2Cl2

The chlorination must be controlled as excess chlorine converts trichloromethanesulfenyl chloride into carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...

. 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
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

 is used for the reducing agent M.

Uses of CSCl2

CSCl2 is mainly used to prepare compounds with the connectivity CSX2 where X = OR, NHR
Thiourea is an organosulfur compound of with the formula SC2 . It is structurally similar to urea, except that the oxygen atom is replaced by a sulfur atom, but the properties of urea and thiourea differ significantly. Thiourea is a reagent in organic synthesis. "Thioureas" refers to a broad...

. Such reactions proceed via intermediate such as CSClX. Under certain conditions, one can convert primary amines into isothiocyanate
Isothiocyanate is the chemical group –N=C=S, formed by substituting sulfur for oxygen in the isocyanate group. Many natural isothiocyanates from plants are produced by enzymatic conversion of metabolites called glucosinolates. These natural isothiocyanates, such as allyl isothiocyanate, are also...

CSCl2 also serves as a dienophile to give, after reduction 5-thiacyclohexene derivatives. Thiophosgene is also known as the appropriate reagent in Corey-Winter
Corey-Winter olefin synthesis
The Corey-Winter olefin synthesis is a series of chemical reactions for converting 1,2-diols into olefins. It is named for the American chemist and Nobelist Elias James Corey and the American-Estonian chemist Roland Arthur Edwin Winter....

synthesis for stereospecific converting 1,2-diols into olefins.
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