Aniline does not undergo Friedel-Crafts reaction because

(A) It forms salt with the Lewis acid catalyst, AlCl₃.
(B) Nitrogen of aniline acquires negative charge.
(C) Nitrogen of aniline acquires positive charge.
(D) Nitrogen acts as a strong deactivating group in the further reaction.

Choose the correct answer from the options given below

The correct answer is (A), (C) and (D) only.

Step-by-step Explanation:

1. Understanding Friedel-Crafts Reaction and Catalyst:
Friedel-Crafts reactions (both alkylation and acylation) are electrophilic aromatic substitution reactions. These reactions require a Lewis acid catalyst, such as anhydrous aluminium chloride (AlCl₃), to generate the electrophile from the alkyl or acyl halide.

2. Acid-Base Interaction (Forming a Salt - Statement A and Statement C):
Aniline (C₆H₅NH₂) is a strong Lewis base due to the presence of a lone pair of electrons on the nitrogen atom of the amino (-NH₂) group. When AlCl₃ (a strong Lewis acid) is added to aniline, instead of acting as a catalyst for the alkylation/acylation of the ring, it undergoes a rapid acid-base reaction with the amino group. The lone pair of nitrogen is donated to the vacant d-orbital of aluminium, forming a salt/adduct:
C₆H₅NH₂ + AlCl₃ → C₆H₅NH₂⁺-AlCl₃^-
As a result of this coordinate bond formation, the nitrogen atom of aniline acquires a positive charge (Statement C), not a negative charge (Statement B). Thus, Statement A and Statement C are correct, while Statement B is incorrect.

3. Deactivation of the Benzene Ring (Statement D):
In aniline, the -NH₂ group is highly activating towards electrophilic substitution. However, in the salt formed (C₆H₅NH₂⁺-AlCl₃^-), the nitrogen atom carries a positive charge. This positively charged nitrogen acts as a very strong electron-withdrawing group via the inductive effect (-I effect). It strongly deactivates the benzene ring towards further electrophilic aromatic substitution reactions, preventing the Friedel-Crafts reaction from occurring.

Conclusion:
Aniline fails to undergo Friedel-Crafts reaction because:
(A) It forms a salt with the Lewis acid catalyst, AlCl₃.
(C) Nitrogen of aniline acquires a positive charge in this salt.
(D) The positively charged nitrogen acts as a strong deactivating group in the further reaction.
Therefore, statements (A), (C), and (D) are correct.