Tetrachloroethylene oxide

Tetrachloroethylene oxide, perchloroethylene oxide (PCEO) or tetrachlorooxirane, is the perchlorinated analogue of ethylene oxide and a proposed metabolite of tetrachloroethylene.^[3] It is a halogenated epoxide with the formula C₂Cl₄O. Tetrachloroethylene oxide is fairly stable but rearranges to trichloroacetyl chloride at higher temperatures.^[4]

Tetrachloroethylene oxide

Names
IUPAC name tetrachlorooxirane
Other names Perchloroethylene oxide (PCEO), Epoxyperchlorovinyl, Tetrachloroepoxyethane
Identifiers
CAS Number	16650-10-5 Y
3D model (JSmol)	Interactive image
ChemSpider	26022
PubChem CID	27973
UNII	2PJ36AO63Q
CompTox Dashboard (EPA)	DTXSID60168115
InChI InChI=1S/C2Cl4O/c3-1(4)2(5,6)7-1 Key: PHEPAUSSNBXGQO-UHFFFAOYSA-N
SMILES ClC1(Cl)C(Cl)(Cl)O1
Properties
Chemical formula	C2Cl4O
Molar mass	181.82 g·mol−1
Appearance	liquid
Density	1.72 g/cm3[1]
Melting point	–58 °C[2]
Boiling point	110 °C [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Production

Tetrachloroethylene oxide was first synthesised by the English chemist Frederick William Kirkbride in 1940, by exposing a mixture of oxygen and chlorine in tetrachloroethylene to UV light.^[5]

Tetrachloroethylene oxide can be obtained by the direct oxidation of tetrachloroethylene under UV light.^[4]

Reactions

Unlike most epoxides, PCEO does not polymerise.^[4]

PCEO reacts with methanol, with mercury(II) chloride as the catalyst, giving methyl trichloroacetate and hydrogen chloride:^[2]

C₂Cl₄O + CH₃OH → CH₃O(CO)CCl₃ + HCl

PCEO reacts with methanolic potassium hydroxide to give potassium oxalate.^[2] It is slowly decomposed by dilute acid or base solutions, giving off carbon monoxide, carbon dioxide and hydrogen chloride which was possibly from the further decomposition of the intermediate oxalyl chloride.^[2]

Metabolism

Tetrachloroethylene oxide (PCEO) is a short-living metabolite of tetrachloroethylene. Unlike most epoxide metabolites, PCEO does not exhibit mutagenic or carcinogenic effects.^[6]

It is metabolised to trichloroacetyl chloride which is hydrolysed to trichloroacetic acid.^[7]

See also

• Chloroethylene oxide