Free radical addition to olefins. Part 19.—Trifluoromethyl radical addition to fluoro-substituted propenes and its absolute rate of addition to ethylene

Abstract

The rates of addition of trifluoromethyl radicals to each end of propene, 1,1,1-trifluoropropene and hexafluoropropene have been determined using a competitive technique, taking as a standard the rate of addition to ethylene. The rate of addition of trifluoromethyl radicals to ethylene (2) has been compared with the rate of combination of trifluoromethyl radicals (6), and a value of k₂/k^½₆=(1.6 ± 0.2)× 10³ exp (–2 900 ± 500 cal mol^–1/RT) dm^½ mol^–½ s^–½ was determined (1 cal = 4.184 J). [graphic omitted] Since the value of k₆ is now well established, a new value of the absolute rate of addition of trifluoromethyl radicals to ethylene and to the other olefins can be computed.