Lumière–Barbier method

The Lumière–Barbier method is a method of acetylating aromatic amines in aqueous solutions. An example of this is the acetylation of aniline.

First aniline is dissolved in water using one equivalent of hydrochloric acid:

Then 1.2 equivalents of acetic anhydride is added followed by 1.2 equivalents of aqueous sodium acetate solution. Aniline attacks acetic anhydride followed by deprotonation of the ammonium ion:

Acetate then acts as a leaving group:

The acetanilide product is insoluble in water and can therefore be filtered off as crystals.