The reactivity of organothallium compounds. Kinetics and mechanism of iodination of diarylthallium salts by molecular iodine in dioxane

The kinetics and mechanism of the reactions of diarylthallium trifluoroacet ates with molecular iodine in dioxane. solutions have been studied. The rea ction has the overall second order with the first order with respect to eac h reagent. The effect of substituents in the aromatic ring on the rate cons tant of iodination is described by the equation logk(2) = rho sigma(+)(rho = -1.60, r = 0.97). The reaction is catalyzed by the iodide ion. The activa tion enthalpies and entropies of iodination of diarylthallium trifluoroacet ates in dioxane and di(p-anisyl)thallium trifluoroacetate in various solven ts have been calculated. The effect of solvents on the rate constant of iod ination of di(p-anisyl)thallium trifluoroacetate has been studied. The reac tion mechanism is considered as an electrophilic SEC process.