Trifluoromethyl radicals reaction with ethylene

If the subsequent reactions involve the regeneration of trifluoromethyl radicals by iodine abstraction, e. g- in the reactions with ethylene ... 

Absolute rates for the addition of the methyl radical and the trifluoromethyl radical to dienes and a number of smaller alkenes have been collected by Tedder (Table l)3. Comparison of the rate data for the apolai4 methyl radical and the electrophilic trifluoromethyl radical clearly show the electron-rich nature of butadiene in comparison to ethylene or propene. This is also borne out by several studies, in which relative rates have been determined for the reaction of small alkyl radicals with alkenes. An extensive list of relative rates for the reaction of the trifluoromethyl radical has been measured by Pearson and Szwarc5,6. Relative rates have been obtained in these studies by competition with hydrogen... 

Polar effects also appear to exist in the addition reactions of certain radicals to substituted ethylenes. It is clear from Table II that for electronegative radicals like difluoroamino or hydroxy and to a lesser extent trifluoromethyl radical and hydrogen atom, substitution with donor groups like methyl increases the rate of addition. Substitution with electronegative atoms like fluorine or chlorine has the effect of slowing the rate of addition by hydroxy or trifluoromethyl radicals but the rate of addition of methyl radicals is increased. 

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