Free radical addition to olefins:Part 9. - Addition of methyl radicals to fluoro-ethylenes

A method to determine the relative rate of addition of methyl radicals to each end of a series of fluoroethylenes has been developed and the following differences (Δ) in activation parameters determined. CH 3· + RCH=CH2→k2CH 3CH2ĊHR ΔE2/(kcal mol-1) Δ log A2/(l. mol-1 s-1) ĊH 2=CH2:ĊH2=CHF -0.93±0.2 -0.14±0.03 ĊH2=CHF:ĊHF=CH2 -1.01±0.2 -0.29±0.01 ĊH2=CHF:ĊF 2=CHF 2.6±0.2 1.43±0.02 ĊHF=CF2: ĊF2=CHF +2.41±0.7 +0.4±0.06 ĊF 2=CHF:ĊF2=CF2 1.38±0.4 -1.1±0.04 ĊH2=CHF:ĊH2=CF2 -2.40±0.5 -0.60±0.05 ĊH2=CF2: ĊF2=CH2 +2.94±0.7 1.9±0.06 ĊH 2=CH2:ĊH2=CF2 -4.8±1.0 -1.31±0.09 ĊH2=CH2:ĊF2=CF 2 2.62±1.1 0.92±0.09 ĊH2=CH 2:ĊH2=CHCl -1.87±0.5 -0.54±0.04 ĊH2=CH2:ĊH2=CHCH3 +0.75±0.4 1.04±0.03 These figures show considerably different trends to those observed for the addition of trichloromethyl and heptafluoropropyl radicals to the same olefins.