Room-temperature catalytic fluorination of C1 and C2 chlorocarbons and chlorohydrocarbons on fluorinated Fe3O4 and Co3O4

Abstract

A study of the room-temperature reactions of a series of C₁ and C₂ chlorohydrocarbon and chlorocarbon substrate molecules with fluorinated iron (II, III) oxide and cobalt (II, III) oxide has been conducted. The results show that fluorinated iron(II, III) oxide exhibits an ability to incorporate fluorine into the following substrates in the order: Cl₂CCCl₂ > H₂CCCl₂ > CH₃CCl₃ > CHCl₃ > CH₂Cl₂ > CH₂ClCCl₃ > CCI₄ > CHCl₂CHCl₂. The fluorinated cobalt(II,III) oxide gave the reactivity series CHCl₃ > CCl₄ > H₂CCCl₂ > CHCl₂CHCl₂ > CH₂CI₂ > CH₃CCl₃ > CCl₂CCl₂ > CH₂ClCl₃. Reactions of C₁ chlorohydrocarbon or chlorocarbon probe molecules with fluorinated Fe₃O₄ gave predominately C₁ chlorofluorohydrocarbon and chlorofluorocarbon products, respectively, whereas fluorinated cobalt(II, III) oxide produced predominately C₂ chlorofluorohydrocarbon and chlorofluorocarbons. For fluorinated Co₃O₄ the distribution of C₂ products obtained from C₁ chlorohydrocarbon precursor molecules is consistent with the formation of radical intermediates at strong Lewis acid surfaces. C₂ chlorohydrocarbons exhibit a fluorine for chlorine (F-for-Cl) exchange reaction through the catalytic dehydrochlorination of the substrate to the alkenic intermediate. The F-for-Cl exchange process was dependent upon the ability of the substrate material to undergo dehydrochlorination; the inability of a substrate to undergo dehydrochlorination results in the fluorination process proceeding through the formation of chlorocarbon or chlorohydrocarbon radical intermediates.