Question

Convert, ethanoic acid to ethanol.

Hint:

For industrial purposes, acids are often converted to esters first and then reduced using catalytic hydrogenation (\( H_2 / Ni \)), as \( LiAlH_4 \) is very expensive.

Answer 1

Step 1: Understanding the Concept:
Converting a carboxylic acid to a primary alcohol is a reduction process. Carboxylic acids are difficult to reduce and require strong or specific reducing agents.
Step 2: Detailed Explanation:
Ethanoic acid (\( CH_3COOH \)) is reduced to ethanol (\( CH_3CH_2OH \)) using Lithium Aluminium Hydride (\( LiAlH_4 \)) in dry ether, followed by acid hydrolysis.
Reaction:
\[ CH_3COOH \xrightarrow{\text{(i) } LiAlH_4 / \text{ether}, \text{ (ii) } H_3O^+} CH_3CH_2OH \]
Alternatively, Diborane (\( B_2H_6 \)) can be used. It is often preferred because it specifically reduces the carboxyl group and does not easily reduce other functional groups like nitro or halo groups.
Note: Sodium borohydride (\( NaBH_4 \)) cannot reduce carboxylic acids.
Step 3: Final Answer:
Ethanoic acid is converted to ethanol by reduction with \( LiAlH_4 \) in ether.