Question

Which of the following compounds will undergo self aldol condensation in the presence of cold dilute alkali?

• A. CH2 = CH − CHO
• B. CH ≡ C − CHO
• C. C6H5CHO
• D. CH3CH2CHO

Hint:

Only aldehydes and ketones with \(\alpha\)-hydrogen undergo aldol condensation.

Answer 1

The Correct Option is D

Step 1: Aldol Condensation Mechanism
- Aldol condensation is applicable to aldehydes and ketones possessing at least one \(\alpha\)-hydrogen. 
- A base abstracts the \(\alpha\)-hydrogen, generating an enolate ion, which subsequently attacks another carbonyl substrate. 
Step 2: Evaluation of Provided Compounds 
- \( CH_3CH_2CHO \) (Propionaldehyde) possesses an \(\alpha\)-hydrogen and is thus amenable to aldol condensation. 
- \( CH_2 = CH - CHO \) (Acrolein) and \( CH \equiv C - CHO \) exhibit resonance stabilization, hindering facile enolate formation. 
- \( C_6H_5CHO \) (Benzaldehyde) lacks \(\alpha\)-hydrogen, precluding aldol condensation. 
Conclusion: \( CH_3CH_2CHO \) is capable of undergoing aldol condensation.