The high electron density of the delocalised system attracts electrophiles. Note:Alkenes polarise symmetrical, non-polar molecules such as halogens bromine Br2 and chlorine Cl2 and they become electrophilic because of the high electron density of the π bond.In benzene, delocalisation of the π bonds means the electron density is not high enough to polarise these molecules into becoming electrophiles but is still high enough to attract positive species that are already electrophiles.So catalysts such as halogen carriers and sulfuric acid are needed to polarise these molecules and turn them into electrophiles before they can react with benzene.
Electrophilic Substitution Reactions
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Specification: OCR Chemistry A (H432), A-level. Topic: Benzene.
More in Benzene
- Benzene
- Benzene Structure
- Nitration of Benzene
- Halogenation of Benzene
- Phenol
- Halogen Carriers
- Friedel-Crafts Alkylation
- Friedel-Crafts Acylation
All 16 lessons in Benzene · All OCR A-level Chemistry topics