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Assertion: Aniline does not undergo Friedel-Crafts reaction. Reason: Friedel-crafts is an electrophilic substitution reaction. |
Both Assertion and Reason are correct and the Reason is the correct explanation for the Assertion. Both Assertion and Reason are correct and the Reason is not the correct explanation for the Assertion. Assertion is correct but the Reason is incorrect. Both Assertion and Reason are incorrect. |
Both Assertion and Reason are correct and the Reason is not the correct explanation for the Assertion. |
The correct answer is option 2. Both Assertion and Reason are correct and the Reason is not the correct explanation for the Assertion. Let us analyze both the assertion and the reason in detail: Assertion: Aniline does not undergo Friedel-Crafts reaction. The assertion is true. Aniline \((C_6H_5NH_2)\) does not typically undergo Friedel-Crafts alkylation or acylation reactions effectively. This is because the amino group (-NH2) in aniline is a strong electron-donating group, which deactivates the aromatic ring towards electrophilic substitution in the presence of a strong Lewis acid catalyst (like \(AlCl_3\)). Reason: Friedel-Crafts is an electrophilic substitution reaction. The reason is also true. Friedel-Crafts reactions (both alkylation and acylation) are indeed electrophilic aromatic substitution (EAS) reactions, where an electrophile substitutes a hydrogen atom on the aromatic ring. Explaining the Reason for Aniline's Behavior: Lewis Acid Interaction: In Friedel-Crafts reactions, a Lewis acid catalyst like \(AlCl_3\) is required to generate the electrophile. However, in the presence of aniline, the amino group can coordinate with the Lewis acid \((AlCl_3)\), forming a complex. This interaction withdraws the lone pair of electrons on the nitrogen, reducing the activating effect of the amino group on the benzene ring. This makes the aromatic ring less reactive towards the electrophile.
However, the reason provided (that Friedel-Crafts is an electrophilic substitution reaction) does not explain why aniline specifically does not undergo the reaction. The actual reason is the interaction between the amino group and the Lewis acid catalyst, which deactivates the ring. Therefore, the correct option is: 2. Both Assertion and Reason are correct and the Reason is not the correct explanation for the Assertion. |
Deactivation of the Ring: The complex formed deactivates the benzene ring towards further electrophilic substitution, making the Friedel-Crafts reaction ineffective.