ON THE SRN1-SRN2 MECHANISTIC POSSIBILITIES

For the last years there has been an increasing interest in nucleophil ic substitution reactions that occur through a chain process with radi cals and radical anions as intermediates. The propagation reactions pr oposed have been, among others, the fragmentation of the radical anion intermediate of the substrate to give a radical which reacts with the nucleophile (S(RN)1 mechanism), or the reaction of this radical anion with a nucleophile to give the substitution product (S(RN)2 mechanism ). We will discuss further these two mechanistic possibilities.