# Reactions of Aromatic Compounds

## Vocabulary

### abstraction

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

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

### nitration

addition of a nitro group ${-}{\rm{NO}_2}$ 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

### sulfonation

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