THE NITRATION OF BENZENE

This page gives you the facts and a simple, uncluttered mechanism for the electrophilic substitution reaction between benzene and a mixture of concentrated nitric acid and concentrated sulphuric acid. If you want the nitration mechanism explained to you in detail, there is a link at the bottom of the page.

The facts

Benzene is treated with a mixture of concentrated nitric acid and concentrated sulphuric acid at a temperature not exceeding 50°C. As temperature increases there is a greater chance of getting more than one nitro group, -NO₂, substituted onto the ring.

Nitrobenzene is formed.

or:

The concentrated sulphuric acid is acting as a catalyst.

The formation of the electrophile

The electrophile is the "nitronium ion" or the "nitryl cation", NO₂⁺. This is formed by reaction between the nitric acid and the sulphuric acid.

The electrophilic substitution mechanism

Stage one

Stage two