The interaction of triphenylmethyl salts with α‐methylstyrene and 1,1‐diphenylethylene was investigated. With 1,1‐diphenylethylene at a monomer‐initiator ratio of 2 (room temperature), mainly 1,1,3‐triphenyl‐3‐methyl‐indane was isolated, whereas at a ratio of 100 (−10°C), the dimer 1,1,3,3‐tetraphenylbutene‐1 mainly formed. In both cases no addition of the trityl group was registered. In the interaction of α‐methylstyrene with Ph3C+SbCl 6− at a monomer‐initiator ratio of 2(room temperature) a pure 1,3,3‐trimethyl‐1‐phenylindane was isolated and no addition of the trityl group to the double bond was recorded. The initiation reaction of α‐methylstyrene polymerization by trityl and chlorinated trityl salts was studied at temperatures from −20 to 0°C and different concentrations. The oligomers obtained with (pCI‐C6H4)3C+ were investigated by elemental analysis and fluorescence spectroscopy. The presence of Ph3CH in the reaction mixture was demonstrated by GLC and NMR spectra. The results obtained give evidence that the initiation of α‐methylstyrene polymerization involves hydride abstraction from the monomer.
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.
The initiation of isobutyl, n‐butyl, ethyl, and 2‐chloroethyl vinyl ethers polymerization by trityl ion salts was investigated. The oligomers formed and the reaction mixtures were analyzed by GPC and 1H‐NMR spectroscopy. It is concluded that the initiation proceeds via two competing reactions. The addition of the initiator to the monomer is determined as usual by the electrophilicity of the former and the nucleophilicity of the latter. In order to realize initiation by hydride transfer it is necessary for the monomer to possess a hydrogen atom with hydride mobility and that the cation obtained is sufficiently stable. The relative part of these initiation reactions is determined.
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