Aniline does not undergo Friedel craft reaction because the reagent AlCl3 as an electron deficient acts as Lewis base and only attacks on the sole pair of N (nitrogen) present in aniline to make an insoluble complex that precipitates out and the reaction does not proceed. Since Freidel craft reaction requires Lewis acid as catalyst to the said reaction, it does not apply to aniline. AlCl3 a reagent which was used by Friedel Craft in alkylation and acylation. It increases the probablility and possibility of the aromatic substitution.