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Assertion: p-N, N-dimethylaminobenzaldeh...

Assertion: `p-N, N-`dimethylaminobenzaldehy under-goes benzoin condensation
Reason : The aldehydic `(-CHO)` group is meta directing.

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.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question regarding the assertion and reason related to p-N,N-dimethylaminobenzaldehyde and its ability to undergo benzoin condensation, we will analyze both statements step by step. ### Step 1: Analyze the Assertion **Assertion:** p-N,N-dimethylaminobenzaldehyde undergoes benzoin condensation. - **Explanation:** Benzoin condensation is a reaction between two aldehydes in the presence of a catalyst (usually a base) to form a hydroxy ketone. For this reaction to occur, at least one of the aldehydes must have an alpha hydrogen. In the case of p-N,N-dimethylaminobenzaldehyde, the structure has a benzaldehyde group attached to a benzene ring that also has two dimethylamino groups. However, it lacks alpha hydrogens because the aldehyde carbon is directly bonded to the benzene ring, which does not provide any alpha hydrogen atoms. ### Step 2: Analyze the Reason **Reason:** The aldehydic (-CHO) group is meta directing. - **Explanation:** The directing effects of substituents on a benzene ring are influenced by their electronic properties. The -CHO group is an electron-withdrawing group due to its -I (inductive) and -R (resonance) effects. These effects deactivate the ring towards electrophilic substitution at the ortho and para positions, making the meta position more favorable for substitution. Therefore, the statement that the -CHO group is meta directing is correct. ### Step 3: Conclusion - Both the assertion and the reason are true statements. However, the reason provided does not correctly explain the assertion. The assertion is true because p-N,N-dimethylaminobenzaldehyde can undergo benzoin condensation due to the presence of the dimethylamino group, which can stabilize the intermediate formed during the reaction, despite the absence of alpha hydrogens. The reason provided is correct in its own context but does not relate directly to the assertion about benzoin condensation. ### Final Answer Both the assertion and reason are true, but the reason is not the correct explanation for the assertion. ---
To solve the question regarding the assertion and reason related to p-N,N-dimethylaminobenzaldehyde and its ability to undergo benzoin condensation, we will analyze both statements step by step. ### Step 1: Analyze the Assertion **Assertion:** p-N,N-dimethylaminobenzaldehyde undergoes benzoin condensation. - **Explanation:** Benzoin condensation is a reaction between two aldehydes in the presence of a catalyst (usually a base) to form a hydroxy ketone. For this reaction to occur, at least one of the aldehydes must have an alpha hydrogen. In the case of p-N,N-dimethylaminobenzaldehyde, the structure has a benzaldehyde group attached to a benzene ring that also has two dimethylamino groups. However, it lacks alpha hydrogens because the aldehyde carbon is directly bonded to the benzene ring, which does not provide any alpha hydrogen atoms. ### Step 2: Analyze the Reason ...
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