Return to Contents
Chapter 12 : 
Reactions of Arenes. Electrophilic Aromatic Substitution
Ch 12 contents

Halogenation of Benzene

halogenation of arenes
Reaction type: Electrophilic Aromatic Substitution


Step 1:
The bromine reacts with the Lewis acid to form a complex that makes the bromine more electrophilic.
bromination of benzene
Step 2:
The p electrons of the aromatic C=C act as a nucleophile, attacking the electrophilic Br, and displacing iron tetrabromide. This step destroys the aromaticity giving the cyclohexadienyl cation intermediate.
Step 3:
Removal of the proton from the sp3 C bearing the bromo- group reforms the C=C and the aromatic system, generating HBr and regenerating the active catalyst.


previous page
next page
organic chemistry © Dr. Ian Hunt, Department of Chemistry University of Calgary