Nucleophilic aromatic substitution

• Two main compounds that undergo nucleophilic aromatic substitutions are:

  • pentafluorobenzene derivative
  • diazo-functional benzene
• For pentafluorobenzene, only para-F reacts as that F experiences electron withdrawing effect from 4F neighbours os the activation across the ring is not very strong
• Sn,Ar on diazo compounds introduces a wider range Nu into aniline but requires activation via diazonium salt
• Sandmeyer reaction involves replacing the diazonium group by Nu by using appropriate cuprous Cu(I) salts
• Chlorination of bromination with diazo can give a mixture of products - using sandmegyer synthesis, there is only one product, Cl in para
• Highly activated benzene rings like phenols or anilines can undergo electrophilic aromatic substitution reactions with diazonium salts to give an azo compound