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: Understanding Aldol Condensation 
- Aldol condensation occurs in aldehydes/ketones that contain at least one \(\alpha\)-hydrogen. 
- The \(\alpha\)-hydrogen is removed by a base to form an enolate ion, which then attacks another carbonyl compound. 
Step 2: Analyzing the Given Compounds 
- \( CH_3CH_2CHO \) (Propionaldehyde) contains an \(\alpha\)-hydrogen, allowing aldol condensation. 
- \( CH_2 = CH - CHO \) (Acrolein) and \( CH \equiv C - CHO \) do not easily form enolates due to resonance stabilization. 
- \( C_6H_5CHO \) (Benzaldehyde) lacks \(\alpha\)-hydrogen, preventing aldol condensation. 
Final Answer: \( CH_3CH_2CHO \) undergoes aldol condensation.