Question

State the role of alkaline ${\mathrm{KMnO}}_4$ in the reaction involving the conversion of an alcohol to corresponding carboxylic acid.

Answer 1

Role of alkaline ${\mathrm{KMnO}}_4$ in the conversion of an alcohol to corresponding carboxylic acid

• Alkaline ${\mathrm{KMnO}}_4$ is used as an oxidizing agent in the reaction involving the conversion of an alcohol to corresponding carboxylic acid.
• ${\mathrm{KMnO}}_4$ is a very powerful oxidizing agent.
• Under controlled conditions, ${\mathrm{KMnO}}_4$ oxidizes primary alcohol to carboxylic acids. It first oxidizes the primary alcohol to aldehyde which is further oxidized to carboxylic acid. Hence some amount of aldehyde is also formed during the process.
• For example, Ethanol(Primary alcohol) on heating with alkaline ${\mathrm{KMnO}}_4$produces ethanoic acid(carboxylic acid) with ethanal(aldehyde) as an intermediate product. The reaction is given as:

$\underset{\mathrm{Ethanol}}{{\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{OH}}\stackrel{\mathrm{alkaline}{\mathrm{KMnO}}_4+\mathrm{Heat}}{\to }\underset{\mathrm{Ethanal}}{\left[{\mathrm{CH}}_3-\mathrm{CHO}\right]}\stackrel{}{\to }\underset{\mathrm{Ethanoic}\mathrm{acid}}{{\mathrm{CH}}_3-\mathrm{COOH}}$

Hence, alkaline ${\mathrm{KMnO}}_4$ plays the role of an oxidizing agent in the reaction involving the conversion of an alcohol to corresponding carboxylic acid.