 This intermediate collapses into an aryl radical 3 and a halide anion.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.