Oxygenation by superoxide ion of halogenofluorocarbons (Freons and haloforms) in aprotic solvents

The reactivity of chloro- and bromofluoromethanes (Freons and others) with superoxide ion (O2.-) has been evaluated by cyclic voltammetry in dimethylformamide (DMF). Substitution of fluorine atoms into chloromethanes results in a substantial decrease in their reactivity with O2.- (relative rates: CCl4 much greater than CF4, much greater than CCl4 much greater than FCCl3, CCl4 much greater than F2CCl2, CCl4 much greater than F3CCl, H3CCl much greater than F3CCl, and H2CCl2 much greater than F2CCl2). The bromo derivatives react much faster with O2.- than the corresponding chloro compounds (F3CBr much greater than F3CCl, F2CBr2 much greater than F2CCl2, and FCBr3 much greater than FCCl3). The rates of reaction for HCCl3, HCFCl2, and HCF2Cl are approximately the same, and the reactions appear to have a common path via dehydrochlorination. Reaction stoichiometries, apparent second-order rate constants, and product profiles have been determined for these fluoromethanes and related chlorofluoroethanes.