| Abstract: | The initiation reaction of the polymerization of α-methylstyrene by trityl tetrachloroferate and tritylhexachloroantimonate in 1,2-dichloroethane at 20°C was studied. The rate constants were 14 × 10?3 and 27 × 10?3 L mol?1s?1, respectively. The dissociation constants of tritylterachloroferate (Kd = 0.88 × 10?4M?1) and tritylhexachloroantimonate (Kd = 2.64 × 10?4M?1) was determined. The effect of electron acceptors and donors on the dissociation equilibrium and initiation rate was investigated. It was shown that in strongly dissociated ion pairs such as stable carbenium salts the electron donors and acceptors have no appreciable effect on the magnitude of the dissociation. The temperature dependence of the rate constants in the ?20–+20°C range yielded the following thermodynamic parameters for trityltetrachloroferate: Ei = 8.54 kcal/mol; A = 3.2 × 104 mol?1s?1; ΔH* = 8 kcal/mol; and S* = ?39.8 eu. |
