Thiocarbonic acid is an

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemist ...

acid with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

(or ). It is an analog of carbonic acid (or ), in which all

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

atoms are replaced with sulfur atoms. It is an unstable

hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, t ...

red oily liquid. It is often referred to as trithiocarbonic acid so as to differentiate it from other carbonic acids containing sulfur, such as monothiocarbonic ''O'',''O''-acid , monothiocarbonic ''O'',''S''-acid , dithiocarbonic ''O'',''S''-acid and dithiocarbonic ''S'',''S''-acid (see

thiocarbonate Thiocarbonate describes a family of anions with the general chemical formula (''x'' = 0, 1, or 2): *for ''x'' = 2 it is monothiocarbonate ion *for ''x'' = 1 it is dithiocarbonate ion *for ''x'' = 0 it is trithiocarbonate ion Like the carbonate d ...

s).

Discovery and synthesis

It was first reported in brief by Zeise in 1824 and later in more detail by Berzelius in 1826, in both cases it was produced by the action of

carbon disulfide Carbon disulfide (also spelled as carbon disulphide) is a neurotoxic, colorless, volatile liquid with the formula and structure . The compound is used frequently as a building block in organic chemistry as well as an industrial and chemical n ...

on a hydrosulfide salt (e.g.

potassium hydrosulfide Potassium hydrosulfide is the inorganic compound with the formula KSH. This colourless salt consists of the cation and the bisulfide anion . It is the product of the half-neutralization of hydrogen sulfide with potassium hydroxide. The compound ...

). : Treatment with acids liberates the thiocarbonic acid as a red oil : Both the acid and many of its salts are unstable and decompose via the release of carbon disulfide, particularly upon heating: : An improved synthesis involves addition of barium trithiocarbonate to hydrochloric acid at 0 °C. This method provided samples with which many measurement have been made. Despite its lability, crystals of thiocarbonic acid have been examined by

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

, which confirms the anticipated molecular structure of a trigonal–planar central carbon atom. The C-S bond lengths range from 1.69 to 1.77 Å.

Reactions and derivatives

Thiocarbonic acid is

acidic In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a ...

, with the first p''K''_a being around 2. The second p''K''_a is near 7. It dissolves , but does not react with it. Salts and esters of trithiocarbonic acid are called trithiocarbonates, and they are sometimes called

thioxanthate In chemistry, a thioxanthate is an organosulfur compound with the formula RSCS2X. When X is an alkali metal, the thioxanthate is a salt. When X is a transition metal, the thioxanthate is a ligand, and when X is an organic group, the compounds are ...

s. Thiocarbonic acid reacts with

bifunctional In organic chemistry, when a single organic molecule has two different functional groups, it is called a bifunctional molecule . A bifunctional molecule has the properties of two different types of functional groups, such as an alcohol (), amide ( ...

reagents In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

to give

rings Ring may refer to: * Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry * To make a sound with a bell, and the sound made by a bell :(hence) to initiate a telephone connection Arts, entertainment and media Film and ...

1,2-Dichloroethane The chemical compound 1,2-dichloroethane, commonly known as ethylene dichloride (EDC), is a chlorinated hydrocarbon. It is a colourless liquid with a chloroform-like odour. The most common use of 1,2-dichloroethane is in the production of vin ...

gives ethylene trithiocarbonate ().

Oxalyl chloride Oxalyl chloride is an organic chemical compound with the formula (COCl)2. This colorless, sharp-smelling liquid, the diacyl chloride of oxalic acid, is a useful reagent in organic synthesis. Preparation Oxalyl chloride was first prepared in 1892 ...

gives oxalyl trithiocarbonate ().

Applications

Thiocarbonic acid currently has no significant applications. Its esters find use in RAFT polymerization.

References

{{Authority control Hydrogen compounds Sulfur(−II) compounds Inorganic carbon compounds