The efficiency of alkyl halide initiators in carbocationic polymerization

This scheme has been used to explain qualitatively that neither alkyl halides yielding very unstable (i. e. reactive) wbenium ions nor alkyl halides yielding very stable (i. e. unreactive) carbenium ions are efficient initiators. In the fiist case step (1) and in the second case step (2) is unfav~rable~.~). Other authors criticized this conclusion and offered alternative interpretations for the experimental data4). We now present a theoretical analysis of the initiation efficiency of such systems5) and corroborate our conclusions by direct determination of relative initiation rates of alkyl halide/Lewis acid combinations. I + I