Question

Which reagent can convert acetic acid into ethanol?
A.Na + alcohol
B. ${H_2} + Pt$
C. $LiAl{H_4} + ether$
D.Sn + HCl

Answer 1

In the presence of Sodium (Na), the acetic acid gives sodium salt of acetic acid. The reagent ${H_2} + Pt$ is basically used for the hydrogenation. Aluminum lithium hydride $\left( {LiAl{H_4}} \right)$ is a strong reducing agent and is able to reduce acids to alcohols.

Complete step by step answer:
Acetic acid $\left( {C{H_3}COOH} \right)$ must undergo reduction to form ethanol $\left( {{C_2}{H_5}OH} \right)$.
Aluminum Lithium hydride $\left( {LiAl{H_4}} \right)$ is used as a reducing agent which reduces carbonyl compounds into alcohols. $LiAl{H_4}$ can convert acetic acid into ethanol as it acts as a reducing agent and is capable of reducing carboxylic acids to alcohols.
$C{H_3}COOH\xrightarrow{{LiAl{H_4} + ether}}C{H_3}C{H_2}OH$
acetic acid ethanol
So, when acetic acid is treated with aluminum lithium hydride $\left( {LiAl{H_4}} \right)$ in the presence of ether followed by the hydrolysis in acidic medium yields ethanol as a product.
While when we see other options given in the question and the reason these reagents cannot convert acetic acid into ethanol because,
Reagent Na + alcohol: The acetic acid in the presence of Sodium (Na) gives sodium salt of acetic acid.
Reagent ${H_2} + Pt$: Molecular Hydrogen $\left( {{H_2}} \right)$ and a catalyst like nickel (Ni), Palladium (Pd) or platinum (Pt) is basically used for the hydrogenation.
Reagent Sn + HCl: Sn + HCl can reduce the nitro group but it is not capable of reducing the carbonyl group.
So, $LiAI{H_4} + ether$, is the reagent that can convert acetic acid into ethanol

Therefore, the correct answer is option (C).

Note: Aluminum lithium hydride or LAH, is an inorganic compound having the chemical formula $LiAl{H_4}$ and it is a grey solid. This compound is commonly used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides.