Chemistry of trifluorostyrenes and their dimmers: 3. Solvent effect on the kinetic parameters of the thermal cyclodimerization of α, β, β‐trifluorostyrene 1

Rate constants for the thermal cyclodimerization of α, β, β‐trifluorostyrene (TFS) were determined in six solvents at 393°K. The products of this reaction were mixtures of roughly equal amounts of cis‐trans isomers. The rate constants in 3 solvents, were calculated according to Arrhenius equation. In n ‐hexane, log A = 6.02±0.18, E a = 19.5±0.3 kcal.mol −1 ; in glyme, log A = 5.31 ± 0.19, E a = 18.0±0.3 kcal.mol −1 ; in methanol, Iog A =4.93±0.13, E a =17.1±0.3 kcal mol −1 . All data are consistent with a stepwise radical mechanism, and our reaction in this solvent series obeys an isokinetic relationship, with β = 478°K.