Chloroformic acid

Chloroformic acid is an unstable chemical compound with the formula ClCO₂H. It is the single acyl-halide derivative of carbonic acid (phosgene is the double acyl-halide derivative). Chloroformic acid is also structurally related to formic acid, which has a hydrogen instead of the chlorine. Despite the similar name, it is very different from chloroform.

Chloroformic acid

Structural formula of chloroformic acid Space-filling model of the chloroformic acid molecule
Names
Preferred IUPAC name Carbonochloridic acid[1]
Other names Chloroformic acid Chlorocarbonic acid
Identifiers
CAS Number	463-73-0
3D model (JSmol)	Interactive image
ChemSpider	144299
PubChem CID	164602
CompTox Dashboard (EPA)	DTXSID10196802
InChI InChI=1S/CHClO2/c2-1(3)4/h(H,3,4) Key: AOGYCOYQMAVAFD-UHFFFAOYSA-N InChI=1/CHClO2/c2-1(3)4/h(H,3,4) Key: AOGYCOYQMAVAFD-UHFFFAOYAQ
SMILES ClC(=O)O
Properties
Chemical formula	CHClO2
Molar mass	80.47 g·mol^−1
Density	1.576
Refractive index (nD)	1.426
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

Chloroformic acid itself is too unstable to be handled for chemical reactions. However, many esters of this carboxylic acid are stable and these chloroformates are important reagents in organic chemistry. They are used to prepare mixed carboxylic acid anhydrides used in peptide synthesis. Like other related halocarbons, it is a potentially dangerous alkylating agent.

Important chloroformate esters include 4-nitrophenyl chloroformate, fluorenylmethyloxycarbonylchloride, benzyl chloroformate and ethyl chloroformate.

See also

• Chloroacetic acids
• Dichloroacetic acid
• Trichloroacetic acid

References

1. Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 776–777. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.