Thiocarboxylic acid
Encyclopedia
Thiocarboxylic acids are organosulfur compounds with the general formula RC(O)SH. They are related to carboxylic acid
s by replacement of one oxygen centre by sulfur. Two tautomer
s are possible, written as RC(S)OH and RC(O)SH, but only the latter is observed. In the laboratory, the most common thiocarboxylic acid is thioacetic acid
. A naturally occurring thiocarboxylic acid is 2,6-pyridinedicarbothioic acid
, which functions as a siderophore
. Thiocarboxylic acids are more acidic than the corresponding carboxylic acids.
Thiocarboxylic acids are typically prepared from the acid chloride:
with a Grignard reagent:
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...
s by replacement of one oxygen centre by sulfur. Two tautomer
Tautomer
Tautomers are isomers of organic compounds that readily interconvert by a chemical reaction called tautomerization. This reaction commonly results in the formal migration of a hydrogen atom or proton, accompanied by a switch of a single bond and adjacent double bond...
s are possible, written as RC(S)OH and RC(O)SH, but only the latter is observed. In the laboratory, the most common thiocarboxylic acid is thioacetic acid
Thioacetic acid
Thioacetic acid is an organosulfur compound with the molecular formula CH3COSH. It is a colourless liquid with a strong thiol-like odor. It is used in organic synthesis for the introduction of thiol groups in molecules-Synthesis and properties:...
. A naturally occurring thiocarboxylic acid is 2,6-pyridinedicarbothioic acid
2,6-Pyridinedicarbothioic acid
2,6-Pyridinedicarbothioic acid is an organosulfur compound that is produced by some bacteria. It functions as a siderophore, a small chelating agent with a high affinity for iron. Siderophores are deployed as ion scavengers for microbes. Siderophores solubilize compounds by forming strong complexes...
, which functions as a siderophore
Siderophore
Siderophores are small, high-affinity iron chelating compounds secreted by grasses and microorganisms such as bacteria and fungi...
. Thiocarboxylic acids are more acidic than the corresponding carboxylic acids.
Thiocarboxylic acids are typically prepared from the acid chloride:
- C6H5C(O)Cl + KSH → C6H5C(O)SH + KCl
Dithiocarboxylic acids
Dithiocarboxylic acids, with the formula RCS2H, are also known. They are less common than the monothio derivatives. Such compounds are commonly prepared by the reaction of carbon disulfideCarbon 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...
with a Grignard reagent:
- RMgX + CS2 → RCS2MgX
- RCS2MgX + HCl → RCS2H + MgXCl