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