Halogenation of Aromatic Arenes
This reaction is used as a test for aniline.
However, if monosubstituted derivative is desired, aniline is first acetylated with acetic anhydride and then halogenation is carried out. After halogenation, the acetyl group is removed by hydrolysis and only monosubstituted halogen derivative is obtained.
It may be noted that – NH2 group directs the attacking group at o- and p-positions and therefore, both o- and p-derivatives are obtained.