Question

Which of the following reagents converts aldehydes into primary alcohols?

• A. PCC
• B. \( LiAlH_4 \)
• C. \( KMnO_4 \)
• D. Tollen's reagent

Hint:

\[ LiAlH_4 \text{ and } NaBH_4 \] are important reducing agents for converting: \[ \text{Aldehydes} \rightarrow \text{Primary Alcohols} \] \[ \text{Ketones} \rightarrow \text{Secondary Alcohols} \]

Answer 1

The Correct Option is B

Concept:
Aldehydes can undergo reduction to form primary alcohols. Reducing agents commonly used:
• \( LiAlH_4 \)
• \( NaBH_4 \) Oxidizing agents convert aldehydes into carboxylic acids.

Step 1: Understand the reduction process.
General reaction: \[ RCHO \xrightarrow{[H]} RCH_2OH \] Hydrogen is added across the carbonyl group.

Step 2: Analyze each reagent.
\[ LiAlH_4 \] is a strong reducing agent. It converts aldehydes into primary alcohols. PCC and \( KMnO_4 \) are oxidizing agents. Tollen's reagent is used to test aldehydes and oxidizes them. Thus only: \[ \boxed{LiAlH_4} \] gives primary alcohols.