Under the Friedel Craft Reaction condition, the aniline (a Lewis base) binds to the electrophileAlCl3 (a Lewis acid) to give a coordination complex (a salt). Then, the positive charge on the nitrogen is electron withdrawing, and it pulls the electron density of the aromatic ring by −Ieffect. It therefore, deactivates the ring for further alkylation reactions. Finally, the complex precipitates out of the reaction mixture and the alkylation reaction is not observed.
