Question

Aldehydes containing at least one \(\alpha\)-hydrogen atom undergo a reaction in presence of dilute aq. NaOH to form \(\beta\)-hydroxy aldehyde. Identify the reaction.

• A. Cannizzaro reaction
• B. Aldol reaction
• C. Reformatsky reaction
• D. Wolff–Kishner reaction

Hint:

Dilute alkali with an alpha-hydrogen aldehyde gives a beta-hydroxy aldehyde in the aldol reaction.

Answer 1

The Correct Option is B

Step 1: Clue words
Dilute NaOH, $\alpha$-hydrogen and $\beta$-hydroxy aldehyde all describe aldol addition.

Step 2: Eliminate
None of the other three reactions forms a $\beta$-hydroxy aldehyde from an aldehyde alone.

Step 3: Final Check
The product of this reaction has both an OH group and a CHO group, so the name aldol fits. This confirms option (B).

Final Answer:
Aldol reaction is correct. \[ \boxed{\text{(B) }\text{Aldol reaction}} \]