Question

Carry out the following conversion
Propanoic acid to Ethane

Hint:

Reduction of carboxylic acids can yield alcohols, and further reduction of alcohols can yield alkanes.

Answer 1

To convert propanoic acid to ethane, we perform a reduction reaction using a strong reducing agent like LiAlH₄. The steps are:
1. Reduction of Propanoic acid: Propanoic acid is reduced by lithium aluminum hydride (LiAlH₄) to ethanol. \[ \text{CH}_3\text{CH}_2\text{COOH} \xrightarrow{\text{LiAlH}_4} \text{CH}_3\text{CH}_2\text{OH} \]
2. Reduction of Ethanol to Ethane: Ethanol is then reduced further by a reducing agent like zinc in the presence of hydrochloric acid (Zn/HCl) to ethane. \[ \text{CH}_3\text{CH}_2\text{OH} \xrightarrow{\text{Zn/HCl}} \text{CH}_3\text{CH}_3 \]
Thus, Propanoic acid is first converted to ethanol and then ethanol to ethane.