Studies in azide chemistry. Part II. Photolysis of 2H-hexafluoropropyl and 2-chloro-1,1,2-trifluoroethyl azide

Abstract

U.v. irradiation of 2H-hexafluoropropyl azide yields nitrogen and 3H-hexafluoro-2-azabut-1-ene, which reacts with water to give trifluoroacetaldehyde and undergoes fluoride-initiated isomerisation to 3H-hexafluoro-2-azabut-2-ene. Photolysis of the azide in the presence of an excess of cyclohexane, methylcyclohexane, or cyclohexene yields, after hydrolysis of the initial products, N-cyclohexyl-, N-(1-methylcyclohexyl)-, and N-(cyclohex-2-enyl)-αβββ-tetrafluoropropionamide, respectively. These azide decomposition reactions may be interpreted in terms of the intermediacy of 2H-hexafluoropropylnitrene, just as photolysis of 2-chloro-1,1,2-trifluoroethyl azide alone to give 3-chloro-1,1,3-trifluoro-2-azapropene and in the presence of cyclohexane to provide N-cyclohexylchlorofluoroacetamide may be rationalised in terms of 2-chloro-1,1,2-trifluoroethylnitrene. Treatment of chlorotrifluoroethylene with triethylammonium azide under the conditions used to convert perfluoropropene into 2H-hexa-fluoropropyl azide and perfluoropropenyl azide apparently yields only 2-chloro-1,1,2-trifluoroethyl azide.