Question

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Experimental reaction of $CH _3 Cl$ with aniline and anhydrous $AlCl _3$ does not give $o$ and p-methylaniline.
Reason (R) : The $- NH _2$ group of aniline becomes deactivating because of salt formation with anhydrous $AlCl _3$ and hence yields $m$-methyl aniline as the product.
In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is not the correct explanation of (A).
• C. (A) is true, but (R) is false.
• D. (A) is false, but (R) is true.

Answer 1

The Correct Option is C

The question involves evaluating the truth of two statements: an assertion and a reason, regarding the chemical reaction of CH_3Cl with aniline in the presence of anhydrous AlCl_3.

Assertion (A): The reaction does not give o- and p-methylaniline.

Reason (R): The -NH_2 group of aniline becomes deactivating due to salt formation with anhydrous AlCl_3 and yields m-methyl aniline as the product.

1. The Assertion is true. When aniline reacts with methyl chloride (CH_3Cl) in the presence of anhydrous AlCl_3, the reaction does not favor the formation of ortho (o-) and para (p-) methylaniline because the reaction conditions deactivate the aromatic ring for such substitutions.
2. The Reason is false. The explanation provided in the Reason is incorrect. Aniline itself generally directs electrophilic aromatic substitution to the ortho and para positions. However, in the presence of anhydrous AlCl_3, the -NH_2 group does not become meta-directing by forming a salt with AlCl_3. Instead, the catalyst tends to form complexes with the lone pair on the nitrogen atom, reducing the overall reactivity of the aniline in electrophilic aromatic substitution.

Thus, despite the fact that the assertion is true, the reason provided does not accurately explain why the expected ortho and para products aren't formed. Instead, the activation of the aniline ring is suppressed due to the coordination of the lone pair on nitrogen with AlCl_3, interfering with the Friedel-Crafts alkylation electrophile generation.

The correct answer is: (A) is true, but (R) is false.