RADIOTRACERS IN FLUORINE CHEMISTRY .15. HALOGEN EXCHANGE AND ISOMERIZATION-REACTIONS INVOLVING CHLOROFLUOROETHANES ON FLUORINATED CHROMIA SURFACES LABELED WITH ANHYDROUS HYDROGEN [F-18] FLUORIDE, HYDROGEN [CL-36] CHLORIDE OR 1,1-DI [CL-36] CHLOROTETRAFLUOROETHANE

Series of fluorination and chlorination reactions are observed when CCl2FCClF2 or C2Cl2F4 isomers are flowed at ca. 700 K over fluorinated chromia catalysts that have been labelled by prior treatment with (H18F)-F-18 or (H36Cl)-Cl-36. These reactions result in the incorporation of the radiolabel in each component of the mixtures of C2Cl6-nFn that are formed. The probability of a radiolabel, [F-18] or [Cl-36], in a given component correlates directly with the degree to which that component has been fluorinated or chlorinated on the surface. The isomerization of CCl2FCClF2 to CCl3CF3 is an important reaction on fluorinated chromia at 700 K; [Cl-36] tracer experiments indicate that the process is intramolecular. Isomerization of CClF2CClF2 probably occurs also but is less dominant in the overall behaviour observed.