Polar effects in radical addition reactions: Borderline cases

Abstract

Methyl radicals substituted by one ester or nitrile group are on the borderline between nucleophilic and electrophilic behavior. In addition reactions of these borderline radicals to styrenes, polar effects of both, electron-withdrawing and electron-donating substituents at the alkene, increase the rates. But these polar effects are smaller compared to those of nucleophilic or electrophilic radicals. In consequence, the stability of the radicals formed during the addition of the borderline radicals to styrenes are of major importance for the rate of the reaction.