Reactions of Aromatic Compounds



removal of an atom or a group by a radical

activating group

group on a benzene ring that can make the ring more active than benzene alone

arenium ion

benzene ring that has lost a double bond and formed a carbocation with three equivalent resonance contributors

benzylic carbon

sp3 carbon that is directly attached to a benzene ring

benzyne intermediate

short-lived intermediate of benzene that has a triple bond after the leaving group has left

Birch reduction

reduction of benzene to 1,4-cyclohexadiene using Na, NH3, and methanol

Clemmensen reduction

reaction that removes the oxygen of a carbonyl in an aldehyde or ketone

deactivating group

group on a benzene ring that can make the ring less active than the benzene alone

directing group

substituent on a benzene ring that directs where substitutions will occur

electrophilic aromatic substitution (EAS)

type of reaction involving the formation of a powerful electrophile that will react with benzene to temporarily destroy aromaticity and form a stabilized sigma complex that will then undergo an E1-like elimination to re-form the benzene ring


reaction that occurs when a leaving group is on a benzene ring and there is not a strong EWG on the ring in the ortho and/or para position

free radical

atom, molecule, or ion with one or more unpaired electrons

Friedel-Crafts acylation

reaction that adds an acyl group to the benzene ring

Friedel-Crafts alkylation

reaction that adds an alkyl group to the benzene ring using an alkyl halide or an alkene

Meisenheimer complex

intermediate that contains both the nucleophile and the leaving group


addition of a nitro group NO2{-}{\rm{NO}_2} to the benzene ring

SNAr reaction

nucleophilic substitution reaction of an aromatic group that requires a leaving group (Cl, Br, I, …) and a powerful EWG group (NO2) to be either ortho or para to each other

substituent group

any atom or group that replaces one of the hydrogens found on a benzene ring


addition of a sulfonic acid (SO3H{-}{\rm{SO}_3{H}}) functional group to the benzene ring