Explain electrophilic substitution reaction in amines

In anilines, the maximum electron density is found at ortho- and para- positions of the –NH₂ group. The -NH₂  group is ortho and para directing and is a powerful activating group. The following significant reactions take place under this category:

Reaction of aniline with bromine water at room temperature produces a white precipitate of 2,4,6 – tribromoaniline.

During electrophilic reaction, the main problem encountered is the high reactivity of aromatic amines. Substitution occurs at ortho and para positions. If only monosubstituted aniline derivative is required, then the activating effect of –NH₂ group can be controlled by protecting the –NH₂ group by acetylation with acetic anhydride. The desired substitution reaction is then carried out followed by the hydrolysis of substituted amides to substituted amines.