Animated Solution for Chemistry - Organic Chemistry: Which one of the following is reduced with zinc and hydrochloric acid to give the corresponding hydrocarbon?

The question asks us to identify a compound that can be reduced to a hydrocarbon using zinc and hydrochloric acid. This specific combination of reagents—zinc amalgam and concentrated HCl—is the hallmark of the Clemmensen reduction.

The Clemmensen reduction is a highly specific reaction. It targets carbonyl groups (specifically aldehydes and ketones) and completely strips away the oxygen atom, replacing it with two hydrogen atoms. This transforms the $>\text{C=O}$ group directly into a $>{\text{CH}}_2$ group, yielding an alkane.

Let's look at the choices provided: - Ethyl acetate is an ester. - Acetic acid is a carboxylic acid. - Acetamide is an amide. - Butan-2-one is a ketone.

Esters, carboxylic acids, and amides are generally resistant to Clemmensen reduction because their carbonyl carbons are less electrophilic due to resonance with the adjacent heteroatom (oxygen or nitrogen). However, ketones are prime candidates for this reaction.

When Butan-2-one (${\text{CH}}_3{\text{-CH}}_2{\text{-C(=O)-CH}}_3$) is treated with $\text{Zn(Hg)}$ and $\text{HCl}$, the carbonyl oxygen at the second carbon is removed. The carbon atom then bonds with two hydrogens, resulting in Butane (${\text{CH}}_3{\text{-CH}}_2{\text{-CH}}_2{\text{-CH}}_3$), which is a pure hydrocarbon. Therefore, Butan-2-one is the correct answer.