Thiocarbonic acid

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Thiocarbonic acid
IUPAC name
carbonotrithioic acid
Other names
Trithiocarbonic acid
3D model (JSmol)
ECHA InfoCard 100.008.931
EC Number 209-822-6
MeSH C013321
Molar mass 110.22 g/mol
Appearance red, oily liquid
Density 1.483 g/cm3(liquid)
Melting point −26.8 °C; −16.3 °F; 246.3 K
Boiling point 58 °C; 136 °F; 331 K
Related compounds
Related compounds
Carbonic acid, Thiosulfuric acid
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

Thiocarbonic acid is an inorganic acid which is related to carbonic acid. It is an unstable red oil with the chemical formula H2CS3. It is often referred to as trithiocarbonic acid so as to differentiate it from other thiocarbonates.

Discovery and synthesis[edit]

It was first reported in brief by Zeise in 1824 and later in more detail by Berzelius in 1826,[1] in both cases it was produced by the action of carbon disulfide on a hydrosulfide salt (e.g. potassium hydrosulfide).[2]

CS2 + 2 KSH → K2CS3 + H2S

Treatment with acids liberates the thiocarbonic acid as a red oil

K2CS3 + 2 HX → H2CS3 + 2 KX

Both the acid and many of its salts are unstable and decompose via the release of carbon disulfide, particularly upon heating:

H2CS3 → CS2 + H2S


Thiocarbonic acid currently has no significant applications. It's esters, which are sometimes called thioxanthates, find use in RAFT polymerization.


  1. ^ Berzelius, J. J. (1826). "Ueber die Schwefelsalze" [About the sulfur salts]. Annalen der Physik (in German). 82 (4): 425–458. doi:10.1002/andp.18260820404.
  2. ^ O'Donoghue, Ida Guinevere; Kahan, Zelda (1906). "CLXXIV.—Thiocarbonic acid and some of its salts". J. Chem. Soc., Trans. 89 (0): 1812–1818. doi:10.1039/CT9068901812.