Factors controlling the addition of carbon-centered radicals to alkenes

The addition rate constants of radicals to alkenes are strongly substituent dependent because of enthalpic, polar and steric effects. Recent absolute experimental and high level ab initio data for many prototype additions of small radicals are analyzed with the aid of the state correlation diagram. This leads to a unifying rationalization of the various effects and allows the prediction of rate constants to one order of magnitude or better. Propagation rate coefficients of homo- and copolymerizations and penultimate effects are also discussed.