Reduction of Nitro groups

Electrophilic nitration introduces a deactivating, meta-directing substituents on an aromatic ring. The attached nitrogen is in a high oxidation state, and reduction converts the nitro into an electron donating amino group. Reduction is easily achieved either by catalytic hydrogenation (H₂ + catalyst), or with reducing metals in acid. Examples of this reduction are shown here.

Several alternative methods for reducing nitro groups to amines are known. These include zinc or tin in dilute mineral acid, and sodium sulfide in aqueous ammonia solution. The procedures described above are sufficient for most cases.