Q50 / 150 · MHT CET 2026 (19 April Shift 1) · Chemistry
Which of the following pair of reagents is used for the conversion of carboxylic acid to alcohol ?
- Correct answerA$\text{LiAlH}_4 / \text{H}_3\text{O}^+$
- B$\text{H}_2 / \text{Ni - heat}$
- C$\text{B}_2\text{H}_6 / \text{H}_2\text{O}_2, \text{OH}^-$
- D$\text{H}_2 / \text{Pd}$
Solution
Carboxylic acids are reduced to primary alcohols by strong reducing agents such as lithium aluminium hydride ($\text{LiAlH}_4$) followed by acid hydrolysis ($\text{H}_3\text{O}^+$).
$\text{RCOOH} \xrightarrow{\text{LiAlH}_4} \text{RCH}_2\text{O}^- \text{Li}^+ \xrightarrow{\text{H}_3\text{O}^+} \text{RCH}_2\text{OH}$
Catalytic hydrogenation using $\text{H}_2 / \text{Ni}$ or $\text{H}_2 / \text{Pd}$ does not reduce carboxylic acids.
$\text{B}_2\text{H}_6 / \text{H}_2\text{O}_2, \text{OH}^-$ is the reagent for the hydroboration-oxidation of alkenes to alcohols.
Answer: $\text{LiAlH}_4 / \text{H}_3\text{O}^+$
$\text{RCOOH} \xrightarrow{\text{LiAlH}_4} \text{RCH}_2\text{O}^- \text{Li}^+ \xrightarrow{\text{H}_3\text{O}^+} \text{RCH}_2\text{OH}$
Catalytic hydrogenation using $\text{H}_2 / \text{Ni}$ or $\text{H}_2 / \text{Pd}$ does not reduce carboxylic acids.
$\text{B}_2\text{H}_6 / \text{H}_2\text{O}_2, \text{OH}^-$ is the reagent for the hydroboration-oxidation of alkenes to alcohols.
Answer: $\text{LiAlH}_4 / \text{H}_3\text{O}^+$
Hence, the correct answer is option: 'A'.