Return to Contents Chapter 23: Aryl Halides Ch 23 contents

Nucleophilic Aromatic Mechanism

As we have already seen (chapter 12),  the most common reaction of aromatic systems is electrophilic aromatic substitution  :

Electrophilic aromatic substitution

However, a fundamentally different type of reaction is possible for aryl halides under certain conditions:

This reaction is similar to that of simple nucleophilic substitution at sp3 C

The fundamental requirements for this nucleophilic aromatic substitution reaction are:

There are two fundamental events to a nucleophilic substitution reaction:

   1. formation of the new σ bond from an Ar C to nucleophile
   2. breaking of the σ bond to the leaving group

Depending on the relative timing of these two events, two mechanistic pathways emerge:

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