Select the correct name for the following reaction:

Wolff-Kishner Reduction

The correct answer is Option (2) → Wolff-Kishner Reduction

In the given reaction, a carbonyl compound (aldehyde or ketone) reacts with hydrazine (NH₂NH₂) to form a hydrazone intermediate.

Step 1: Formation of hydrazone

R₂C=O + NH₂NH₂ → R₂C=NNH₂ + H₂O

Step 2: On heating with strong base (KOH) in ethylene glycol, the hydrazone decomposes, releasing nitrogen gas (N₂) and converting the carbonyl group into a methylene group (–CH₂–).

R₂C=NNH₂ → (KOH, heat) → R₂CH₂ + N₂

Thus, the carbonyl group (C=O) is reduced to –CH₂–.

This reaction is called Wolff–Kishner reduction.

It is commonly used to convert aldehydes and ketones into alkanes under strongly basic conditions.

Option-wise Explanation

Option 1: Clemmensen Reduction

Incorrect. Clemmensen reduction also converts carbonyl compounds to alkanes but uses Zn–Hg amalgam with concentrated HCl (acidic medium), not hydrazine and KOH.

Option 2: Wolff–Kishner Reduction

Correct. This reaction uses hydrazine (NH₂NH₂) and KOH in ethylene glycol with heating to convert carbonyl compounds into alkanes.

Option 3: Etard Reaction

Incorrect. Etard reaction converts toluene to benzaldehyde using chromyl chloride (CrO₂Cl₂).

Option 4: Stephen Reaction

Incorrect. Stephen reaction reduces nitriles to aldehydes using SnCl₂ and HCl.