Radical-nucleophilic aromatic substitution

Radical-nucleophilic aromatic substitution or SRN1 in organic chemistry is a type of substitution reaction in which a certain substituent on an aromatic compound is replaced by a nucleophile through an intermediary free radical species: The substituent X is a halide and nucleophiles can be sodium amide, an alkoxide or a carbon nucleophile such as an enolate.

[1] In contrast to regular nucleophilic aromatic substitution, deactivating groups on the arene are not required.

The aryl radical reacts with the nucleophile 4 to a new radical anion 5 which goes on to form the substituted product by transferring its electron to new aryl halide in the chain propagation.

Alternatively the phenyl radical can abstract any loose proton from 7 forming the arene 8 in a chain termination reaction.

Clear-cut cine-substitution would give a 1:1 ratio, but additional steric and electronic factors come into play as well.