BRAINCAKEElectrophilic Substitution
Benzene's delocalised ring is a region of high electron density, so it attracts electrophiles. An electrophile is an electron pair acceptor, usually a positive ion such as NO2+ or RCO+.
Alkenes react with electrophiles by addition, but benzene reacts by substitution: a hydrogen atom on the ring is replaced by the electrophile. Substitution restores the stable delocalised ring, while addition would destroy it and lose the delocalisation energy.
The general mechanism, for an electrophile E+, has two steps.
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More in Aromatic Chemistry
- The Kekulé Model
- The Delocalised Model of Benzene
- Evidence for Delocalisation - Enthalpy of Hydrogenation
- Naming Aromatic Compounds
- Nitration of Benzene
- Mechanism of Nitration
- Uses of Nitration
- Friedel-Crafts Acylation
All 11 lessons in Aromatic Chemistry · All AQA A-level Chemistry topics