What is the mechanism of nucleophilic aromatic substitution?

Here’s the simple version of the nucleophilic aromatic substitution (SNAr) mechanism:

Steps:

1. Attack – A nucleophile (like –OH, –NH₂) attacks the carbon on the ring that has a leaving group (like –Cl).
2. Intermediate – The ring becomes temporarily non-aromatic (called the Meisenheimer complex).
3. Leaving group leaves – The halogen (–Cl, –Br, etc.) goes away.
4. Aromatic ring returns – The product is the aromatic ring with the nucleophile attached.

In short:
Nucleophile comes in → temporary intermediate → leaving group goes out → aromaticity restored.