Question

Identify the reaction in which carbonyl group of aldehydes and ketones is reduced to methylene group on treatment with hydrazine followed by heating with sodium hydroxide in ethylene glycol.

• A. Wolf-Kishner reduction
• B. Clemmensen reduction
• C. Stephen reaction
• D. Etard reaction

Hint:

Chemistry Tip: Wolf-Kishner reduction is preferred for base-stable compounds, while Clemmensen reduction (using $Zn(Hg)/HCl$) is preferred for acid-stable compounds to achieve the same result.

Answer 1

The Correct Option is A

Concept:
Chemistry (Organic Chemistry) - Reduction of Carbonyl Compounds.

Step 1: Analyze the reaction conditions.
The reaction involves treating a carbonyl compound (aldehyde or ketone) with hydrazine ($NH_2NH_2$) to form a hydrazone intermediate.

Step 2: Analyze the second stage of the reaction.
The hydrazone is then heated with a strong base like sodium hydroxide ($NaOH$) or potassium hydroxide ($KOH$) in a high-boiling solvent like ethylene glycol.

Step 3: Identify the structural transformation.
During this process, the carbonyl group ($>C=O$) is completely reduced to a methylene group ($>CH_2$) with the evolution of nitrogen gas.

Step 4: Identify the named reaction.
This specific sequence of reagents ($NH_2NH_2$ followed by base/glycol) is the defining characteristic of the Wolff-Kishner reduction. $$ \therefore \text{The reaction is the Wolff-Kishner reduction.} $$