LOW-TEMPERATURE ADDITION OF MOLECULAR FLUORINE TO UNSATURATED PERFLUOROHYDROCARBONS

Calorimetry and ESR spectroscopy were used to study the low-temperatur e fluorination (77-300 K) of unsaturated perfluorohydrocarbons. In the solid phase at 77-100 K (glassy or crystalline state) fluorination do es not occur. On transition from glassy systems to the overcooled liqu id state formation of molecular complexes in which fluorine is attache d to the >C=C< bond becomes possible. These complexes are stabilized o n crystallization of the system; with a further increase in temperatur e, efficient addition of molecular fluorine takes place in the crystal phase. However, the addition of fluorine by some chain or carbene mec hanism must not be ruled out for such systems. Thus, in the case of he xafluoropropylene trimer, the addition proceeds as a chain reaction pr oducing long-living free radicals at the initial stage.