Uses Of Carboxylic Acids

To solve the problem, we need to identify the reagent that can convert CH₃COOH (acetic acid) to CH₃-CH₂-OH (ethanol).

1. Understanding the Reaction:
The starting compound, CH₃COOH, is a carboxylic acid (acetic acid), and the product, CH₃-CH₂-OH, is a primary alcohol (ethanol). This conversion involves reducing the carboxylic acid to its corresponding alcohol, which means reducing the -COOH group to -CH₂OH. Ethanol has two carbons, matching acetic acid, so this is a straightforward reduction.

2. Analyzing the Reduction of Carboxylic Acids:
Carboxylic acids are relatively stable and require strong reducing agents to be converted to alcohols. Common reagents for this reduction include:
- LiAlH₄ (lithium aluminum hydride), a strong reducing agent that can reduce carboxylic acids to primary alcohols.
- NaBH₄ (sodium borohydride), which is milder and typically reduces aldehydes and ketones to alcohols but not carboxylic acids.
- H₂ with a catalyst like Pt (catalytic hydrogenation), which is not typically effective for reducing carboxylic acids to alcohols under standard conditions.
- Na and C₂H₅OH, which is used in the Bouveault-Blanc reduction to reduce esters to alcohols, not carboxylic acids directly.

3. Evaluating the Options:
- (A) LiAlH₄/ether: LiAlH₄ is a strong reducing agent that can reduce carboxylic acids to primary alcohols. The reaction proceeds as follows:
CH₃COOH + LiAlH₄ → CH₃CH₂OH (after hydrolysis). Ether is used as a solvent to facilitate the reaction.
- (B) H₂, Pt: Catalytic hydrogenation with H₂ and Pt is not effective for reducing carboxylic acids to alcohols under standard conditions; it’s more suited for reducing alkenes or alkynes.
- (C) NaBH₄: Sodium borohydride is a milder reducing agent and does not reduce carboxylic acids to alcohols; it typically reduces aldehydes and ketones.
- (D) Na and C₂H₅OH: This combination is used in the Bouveault-Blanc reduction, which reduces esters to alcohols, not carboxylic acids directly.

Final Answer:
The reagent that can perform the conversion is LiAlH₄/ether, so the answer is (A).