Question

Aniline does not show Friedel-Crafts reaction.

Hint:

Aniline does not undergo Friedel-Crafts reactions because the electron-donating nature of the amino group deactivates the ring towards electrophilic substitution and also forms a complex with the Lewis acid catalyst.

Answer 1

Aniline does not undergo the Friedel-Crafts reaction due to the presence of the amino group (\(-\text{NH}_2\)) attached to the benzene ring. The amino group is an electron-donating group through its lone pair of electrons on nitrogen. This electron-donating effect increases the electron density on the benzene ring, making the ring more reactive towards electrophilic attack. However, the presence of the amino group also reduces the reactivity of the ring towards the Friedel-Crafts alkylation and acylation reactions. In Friedel-Crafts reactions, a Lewis acid such as AlCl\(_3\) is used as a catalyst to generate an electrophile, but the lone pair on nitrogen in aniline can coordinate with the Lewis acid, which deactivates the catalyst and inhibits the reaction. Hence, aniline does not show Friedel-Crafts reactions.