Question

Name an alcohol and a carboxylic acid having two carbon atoms in their structures. Draw their structures and state how this alcohol can be converted into a carboxylic acid. What happens when these two compounds react in the presence of an acid? Write chemical quations for the reactions involved in the two cases mentioned above.

Answer 1

An alcohol with two carbon atoms is ethanol (C₂H₅OH).

Structure: \[\begin{array}{cc}
\ce{H}\phantom{...}\ce{H}\phantom{..}\\
|\phantom{....}|\phantom{..}\\
\ce{H - C - C - OH}\\
|\phantom{....}|\phantom{..}\\
\ce{H}\phantom{...}\ce{H}\phantom{..}\\
\end{array}\]

A carboxylic acid with two carbon atoms is Ethanoic acid (CH₃COOH).

Structure: \[\begin{array}{cc}
\ce{O}\phantom{......}\\
||\phantom{......}\\
\ce{H - C - C - OH}\\
|\phantom{.......}\\
\ce{H}\phantom{.......}\\
\end{array}\]

Conversion of Ethanol to Ethanoic Acid:

Ethanol is oxidized to ethanoic acid in the presence of an oxidizing agent like alkaline potassium permanganate (KMnO₄) or acidified potassium dichromate (K₂Cr₂O₇).

Reaction:

\[\ce{C2​H5​OH + 2[O] ->[KMnO4​/K2​Cr2​O7] ​​CH3​COOH + H2​O}\]

Reaction Between Ethanol and Ethanoic Acid:

When ethanol reacts with ethanoic acid in the presence of concentrated sulfuric acid (H₂SO₄) as a catalyst, it forms ethyl ethanoate (ester) and water. This reaction is called esterification.

Reaction:

\[\ce{CH3​COOH + C2​H5​OH ->[Conc. H2​SO4​​] CH3​COOC2​H5​ + H2​O}\]

Therefore, ethanol can be converted into ethanoic acid by oxidation, and ethanol and ethanoic acid react to form an ester (ethyl ethanoate) and water.