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

Electrophilic Aromatic Substitution of Polycyclic Aromatics

electrophilic aromatic substitution of naphthalene

For example, the nitration of naphthalene proceeds to give mainly 1-nitronaphthalene:

nitration of naphthalene

This selectivity can be rationalised by drawing the resonance structures for intermediates produced by attack of the electrophile at the 1- and 2-positions.  Attack at the 1- position gives an intermedaite that is represented by 7 resonance contributors of which 4 leave the aromaticity of the other ring intact. In contrast attack at the 2-position gives an intermediate with 6 resonance contributors in which only 2 have the aromaticity of the other ring intact.

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