Question

Statement-I: Two different aldehydes on cross aldol condensation always give four products.
Statement-II: Among benzaldehyde and acetophenone, only acetophenone reacts with semicarbazide.

• A. Statement-I and Statement-II both are correct
• B. Statement-I is incorrect, Statement-II is correct
• C. Statement-I is correct, Statement-II is incorrect
• D. Statement-I and Statement-II both are incorrect

Hint:

All aldehydes and ketones react with semicarbazide, irrespective of $\alpha$-hydrogen.

Answer 1

The Correct Option is C

Let's break down and analyze the given statements one by one to understand their validity:

Statement-I: Two different aldehydes on cross aldol condensation always give four products.

Explanation: Cross aldol condensation involves the reaction between two different aldehydes, each possessing α-hydrogen atoms. When two different aldehydes react, they can form a variety of products due to the combination possibilities. The reaction sequence is as follows:

• One aldehyde can act as an electrophile, and the other as a nucleophile, producing a mixed aldol product.
• The roles can be reversed, giving another mixed aldol product.
• Each aldehyde can also react with itself, forming two different self-condensation products.

These reactions lead to a total of four possible products. Therefore, Statement-I is correct.

Statement-II: Among benzaldehyde and acetophenone, only acetophenone reacts with semicarbazide.

Explanation: Semicarbazide reacts with carbonyl compounds to form semicarbazones. Benzaldehyde (an aromatic aldehyde) does react with semicarbazide to form a semicarbazone. Therefore, the claim that only acetophenone reacts with semicarbazide is incorrect. Both benzaldehyde and acetophenone can react with semicarbazide, forming their respective semicarbazones.

Conclusion:

• Statement-I is correct because cross aldol condensation reactions typically yield four products when considering different combination possibilities between two aldehydes.
• Statement-II is incorrect because both benzaldehyde and acetophenone can react with semicarbazide to form semicarbazones.

Thus, the correct answer is: Statement-I is correct, Statement-II is incorrect.