Tetrachloroethylene oxide, perchloroethylene oxide (PCEO) or tetrachlorooxirane, is the perchlorinated analogue of ethylene oxide and a proposed metabolite of tetrachloroethylene.Raat, W. K. d. (2003). 133 Tetrachloroethylene (PER). Sweden: Arbetslivsinstitutet. It is a halogenated epoxide with the formula . Tetrachloroethylene oxide is fairly stable but rearranges to trichloroacetyl chloride at higher temperatures.
Production The synthesis of tetrachloroethylene oxide via the oxidation of tetrachloroethylene was described by the French chemist A. Besson in 1894. He identified the compound as the epoxide of tetrachloroethylene, noted its boiling point as 110 °C and named it "oxide of perchlorinated ethylene" (oxyde d'éthylène perchloré).A. Besson (1894), "Sur la préparation de l’éthylène perchloré et l’action de l’oxygène ozonisé sur ce corps" in Comptes rendus de l’Académie des sciences, 118 (24), p. 1347-1350
Tetrachloroethylene oxide was later synthesised by the English chemist Frederick William Kirkbride in 1940, by exposing a mixture of oxygen and chlorine in tetrachloroethylene to UV light.Oxidation of Perchloroethylene, Official Gazette of the United States Patent Office. (1943)
Tetrachloroethylene oxide can be obtained by the direct oxidation of tetrachloroethylene under UV light.
Reactions Unlike most epoxides, PCEO does not polymerise.
PCEO reacts with methanol, with mercury(II) chloride as the catalyst, giving methyl trichloroacetate and hydrogen chloride:
PCEO reacts with methanolic potassium hydroxide to give potassium oxalate. 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. Metabolism Tetrachloroethylene oxide (PCEO) is a short-living metabolite of tetrachloroethylene. Unlike most epoxide metabolites, PCEO does not exhibit mutagenic or carcinogenic effects.Maltoni, Cesare; Selikoff, Irving J; New York Academy of Sciences, [https://archive.org/details/livinginchemical0534unse/page/n10/mode/ ALKYLATING AND ACYLATING AGENTS] Living in a chemical world: occupational and environmental significance of industrial carcinogens (1988), page 629
It is metabolised to trichloroacetyl chloride which is hydrolysed to trichloroacetic acid.Testa, B., Mayer, J. M. (2003). Hydrolysis in Drug and Prodrug Metabolism. page 633
See also Chloroethylene oxide
References