Chemistry of Aromatic Compounds Electrophilic Aromatic Substitution Directing Effects Side-chain Reactions Synthesis Nucleophilic Aromatic Substitution

Electrophilic Aromatic Substitution

EAS Reactions of Benzene

Bromination / Chlorination

Bromination Mechanism

Reaction Profile

Nitration

Nitration Mechanism

Nitration of Toluene

Sulfonation is Reversible

Desulfonation

Friedel-Crafts Acylation

1st, Formaton of Electrophile

Acylation Mechanism

Intermediate is Resonance-Stabilized

An Acylation

Friedel-Crafts Alkylation

Mechanism

Unexpected Product?

Carbocations Rearrange…

1o RX Typically Undergoes Shift

Straight-chain Alkylation can be Accomplished in 2 steps: Acylation, then Reduction

Side Chain Reactions 1) Reduction of Aromatic Ketones

2) Oxidation of Alkyl Substituents

3) Benzylic Bromination with NBS

5) Reduction of Nitro Groups

Directing Effects

ortho/para-Directing Activating Groups

Nitration of Anisole

Nitration Affords ortho and para Products

Activating ortho/para directors

Nitration of Toluene

meta-Directing Deactivating Groups

Electron-Withdrawing Nitro Group Directs meta

meta Directors

Comparison

More Limitations with Friedel Crafts Reactions

Substituent Summary

Halogens are the Anomaly Deactivators and o,p-Directors

Reactions of Rings With Two or More Substituents

The (More) Activated Ring Reacts

Mixtures with Conflicting Directing Effects

Provide the Reagents

Must Acylate First

Sulfonic Acid Blocks para Position

Problem Set: Give the Reagents

Provide the Reagents