Aromatic Substitution Reactions: Electrophilic Aromatic Substitution (SEAr) & Nucleophilic Aromatic Substitution (SNAr/Benzyne)

Friedal-Crafts Acylation (SEAr)

Benzene + Acyl group -----------------------> Benzene w/ ketone and alkyl chain *Caution: Cannot use this rxn to attach an aldehyde directly on benzene ring -Cannot be used if there is a meta director substituent already on the ring

Sulfonation (SEAr)

Benzene + H2SO4 (fuming) -----------------------> Benzene w/ SO3H substituent *Useful block (protecting) group since reaction is reversible Reverse reaction: Benzene w/ SO3H + dilute H2SO4 -----------------------> Benzene + H2SO4

Nitration (SEAr)

Benzene + HNO3/H2SO4 -----------------------> Benzene w/ NO2 substituent

Halogenation (SEAr)

Benzene + X2/AlX3 -----------------------> Halogenated benzene + HX

Friedal-Crafts Alkylation (SEAr)

Benzene + alkyl Halide -----------------------> Benzene w/ alkyl substituent *Caution: Possibility of carbocation rearrangement -Choose alkyl group wisely -Cannot be used if there is a meta director substituent already on the ring

Addition-Elimination (SNAr)

Benzene w/ LG & EWG group + :Nu/heat -----------------------> Disubstituted benzene w/ Nu in place of LG

Elimination-Addition (Benzyne)

Benzene w/ LG + 1. NaOH (or NaNH2) 2. HCl -----------------------> Benzene w/ Nu in place of LG *Para product- "Ipso" Ortho product- "Cine" *Does not require EWG

Reduction of Nitro group

Benzene w/ NO2 + 1. Fe or Zn, HCl 2. NAOH -----------------------> Aniline

Clemenson Reduction

Benzene w/ acyl group + Zn(Hg)/HCl, heat -----------------------> Benzene w/ alkyl chain