The persistent radical effect: A principle for selective radical reactions and living radical polymerizations

Selective radical reactions and living radical polymerizations were discussed. Whenever in a chemical system transient and persistent radicals are formed with equal or similar rates, their cross-reaction products are produced with high selectivity. This rection combined with the reluctance of persistent species causes a buildup of a considerable excess of the persistent over the transient species, and this excess then steers the reaction system toward the cross-reaction channel.