# Electrophilic Aromatic Substitution

### Mechanism of Electrophilic Aromatic Substitution (EAS)

Take Note
• Benzene/aromatics typically behave as nucleophiles and react with electrophiles
• Prefer to do substitution since this preserves the aromaticity
• Proceeds by addition/elimination sequence resulting in an overall substitution.
• The different EAS reactions you will learn only differ by the electrophile conditions.
Take Note
• The cyclohexadienyl cation intermediate (sometime called a sigma complex or arenium ion) and its resonance structures are important in understanding more advanced concepts such as the effect of other substituents on rate and orientation of electrophilic attack.