Question

Which of the following aldehydes exhibits Cannizzaro reaction when heated with strong alkali?

• A. Benzaldehyde
• B. Acetaldehyde
• C. Propionaldehyde
• D. Butyraldehyde

Hint:

Cannizzaro reaction needs an aldehyde with no alpha-hydrogen.

Answer 1

The Correct Option is A

Step 1: Reaction
$2\,\text{C}_{6}\text{H}_{5}\text{CHO}+\text{NaOH}\rightarrow\text{C}_{6}\text{H}_{5}\text{CH}_{2}\text{OH}+\text{C}_{6}\text{H}_{5}\text{COONa}$

Step 2: Reason
No $\alpha$-hydrogen means the base cannot form an enolate, so disproportionation occurs.

Step 3: Result
Option (A) is correct.

Final Answer:
Benzaldehyde lacks an alpha hydrogen, so it gives the Cannizzaro reaction. \[ \boxed{\text{(A) }\text{Benzaldehyde}} \]