Electrophilic aromatic substitution

Nitration of benzene

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Nitration of benzene firstly involves the formation of a very powerful electrophile, the nitronium ion, which is linear. This occurs following the interaction of two strong acids, sulfuric and nitric acid. Sulfuric acid is the stronger acid and it protonates the nitric acid on the OH group so that a molecule of water can leave.

Benzene attacks the positively charged nitrogen atom of the electrophile, where one of the N=O bonds is broken at the same time. This is followed by rapid loss of a proton to regenerate the aromaticity.