AIIMS2019Chemistry-Organic Chemistry

AIIMS 2019 Chemistry Aromatic Compounds MCQ Question

Type: MCQ-conceptual-Medium-Class 11

Assertion: Anhydrides are more reactive than ester for nucleophilic substitution.

Reason:– R.COO\text{R.COO}^{-} is better leaving group than R-O\text{R-O}^{-}

A

If both assertion and reason are true and reason is the correct explanation of assertion.

B

If both assertion and reason are true but reason is not the correct explanation of assertion.

C

If assertion is true but reason is false.

D

If both assertion and reason are false.

Correct Answer

Option A

Detailed Explanation

The reaction is classified as aromatic electrophilic substitution because it involves the substitution of a hydrogen atom on an aromatic ring by an electrophile, maintaining the aromaticity of the compound. In this process, the electrophile attacks the π-electron cloud of the aromatic system, leading to the formation of a sigma complex before the aromaticity is restored by the loss of a proton (H⁺).

Other options are incorrect as nucleophilic substitution typically involves a nucleophile attacking an electrophilic carbon in aliphatic compounds, elimination reactions result in the removal of small molecules (like H₂O or HCl) to form double or triple bonds, and addition reactions involve the addition of atoms or groups across a double bond, which does not apply to the preservation of aromaticity in this context.

Found an issue with this question?