Directions: In the following questions, A statement of Assertion (A) ...
The carboxyl group (-COOH) is deactivating group because it is electron with drawing group. It decreases the electron density at benzene ring, hence deactivates it towards electrophilic substitution reactions.
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Directions: In the following questions, A statement of Assertion (A) ...
Assertion (A): Benzoic acid does not undergo Friedel-Crafts reaction.
Reason (R): The carboxyl group is activating and undergoes electrophilic substitution reaction.
Explanation:
Benzoic acid:
Benzoic acid is an aromatic carboxylic acid with the chemical formula C6H5COOH. It contains a carboxyl group (-COOH) attached to a benzene ring. The presence of the carboxyl group makes benzoic acid a unique compound with specific reactivity.
Friedel-Crafts reaction:
Friedel-Crafts reaction is a classic example of electrophilic aromatic substitution (EAS) reaction. It involves the substitution of a hydrogen atom on an aromatic ring with an electrophile. In the presence of a Lewis acid catalyst, such as aluminum chloride (AlCl3), the electrophile attacks the aromatic ring, leading to the formation of a new substituted product.
Reasoning:
The carboxyl group in benzoic acid is activating towards electrophilic substitution reactions. This means that it enhances the reactivity of the benzene ring towards electrophiles. However, benzoic acid does not undergo the Friedel-Crafts reaction.
Explanation of Assertion (A):
Benzoic acid does not undergo the Friedel-Crafts reaction. This can be attributed to the presence of the carboxyl group, which deactivates the aromatic ring towards electrophilic substitution reactions. The carboxyl group has a strong electron-withdrawing effect due to the resonance of the adjacent carbonyl group. This electron-withdrawing effect reduces the electron density on the benzene ring, making it less reactive towards electrophiles. As a result, benzoic acid does not participate in the Friedel-Crafts reaction.
Explanation of Reason (R):
The reason provided is partially correct. The carboxyl group in benzoic acid is indeed activating towards electrophilic substitution reactions. It enhances the reactivity of the benzene ring towards electrophiles. However, this does not explain why benzoic acid does not undergo the Friedel-Crafts reaction. The deactivating effect of the carboxyl group on the benzene ring is the main reason for its lack of reactivity in the Friedel-Crafts reaction.
Conclusion:
Both the assertion and reason are true, but the reason does not provide a correct explanation for the assertion. Therefore, option C is the correct answer.