Question

Given below are two statements :
Statement I : Acidity of -hydrogens of aldehydes and ketones is responsible for Aldol reaction.
Statement II : Reaction between benzaldehyde and ethanal will NOT give Cross – Aldol product.In the light of above statements, choose the most appropriate answer from the options given below.

• A. Both Statement I and Statement II are correct.
• B. Both Statement I and Statement II are incorrect.
• C. Statement I is incorrect but Statement II is correct.
• D. Statement I is correct but Statement II is incorrect.

Answer 1

The Correct Option is D

Explanation of Statement I:

Aldehydes and ketones with at least one \( \alpha \)-hydrogen can undergo an aldol reaction due to the acidity of the \( \alpha \)-hydrogens.
This acidity allows the formation of an enolate ion, which then attacks the carbonyl carbon of another molecule, leading to the aldol product.
Therefore, Statement I is correct.

Explanation of Statement II:

Benzaldehyde does not contain an \( \alpha \)-hydrogen, so it cannot form an enolate ion.
However, ethanol (in this context, likely meaning acetaldehyde) does have \( \alpha \)-hydrogens and can participate in the aldol reaction with itself or with other compounds that can form enolate ions.
Thus, a cross-aldol product can form between benzaldehyde and acetaldehyde (ethanal).
Therefore, Statement II is incorrect.

Conclusion:

Statement I is correct, but Statement II is incorrect. The correct answer is Option (4).

Answer 2

Step 1: Understanding Statement I.
Statement I says: "Acidity of α-hydrogens of aldehydes and ketones is responsible for Aldol reaction."
- The aldol reaction requires the formation of an enolate ion from the aldehyde or ketone.
- Enolate formation occurs because α-hydrogens (hydrogens on the carbon adjacent to the carbonyl group) are acidic.
- These acidic α-hydrogens are deprotonated under basic conditions to form the enolate ion, which acts as a nucleophile in the aldol reaction.
Hence, Statement I is correct.

Step 2: Understanding Statement II.
Statement II says: "Reaction between benzaldehyde and ethanal will NOT give Cross – Aldol product."
- Benzaldehyde (an aromatic aldehyde) has no α-hydrogens; hence, it cannot form an enolate ion.
- Ethanal (acetaldehyde) has α-hydrogens and can form an enolate ion.
- In cross-aldol condensation, the enolate ion from ethanal can attack the carbonyl carbon of benzaldehyde to form a cross-aldol product.
- Therefore, the reaction *will* give a cross-aldol product.
Hence, Statement II is incorrect.

Step 3: Final conclusion.
- Statement I is correct.
- Statement II is incorrect.

Final answer:
\[ \boxed{ \text{Statement I is correct but Statement II is incorrect.} } \]