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

Sulfonation of  Benzene

sulfonation of arenes

Reaction type: Electrophilic Aromatic Substitution


Step 1:
The p electrons of the aromatic C=C act as a nucleophile, attacking the electrophilic S, pushing charge out onto an electronegative O atom. This destroys the aromaticity giving the cyclohexadienyl cation intermediate.
sulfonation of arenes
Step 2:
Loss of the proton from the sp3 C bearing the sulfonyl- group reforms the C=C and the aromatic system.
Step 3:
Protonation of the conjugate base of the sulfonic acid by sulfuric acid produces the sulfonic acid.



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