HETEROLYTIC C-F BOND-ENERGIES AND STABILITIES OF POLY(PERFLUOROETHERS)

The heterolytic strengths of various C-F bonds adjacent to oxygen in the perfluoroethers CF3OCF3, CF3OCF2CF3, CF3OCF2OCF3, CF3OCF2CF2OCF3 and CF3OCF2CF(CF3)OCF3 have been calculated at the MP-2 level with a polarized double-zeta basis set. These C-F bonds all have similar strengths (233-238 kcal/mol), except for the much weaker methylene C-F bonds (222.6 kcal/mol) in CF3OCF2OCF3, and the stronger methine C-F bond (244.5 kcal/mol) in CF3OCF2CF(CF3)OCF3. These bond strengths are related to the experimental stabilities of commercial Fomblin(R), Krytox(R) and Demnum(R) poly(perfluoroethers). An electrophilic decomposition mechanism involving assisted heterolysis of C-F bonds is proposed.