Question

Hydrolysis of an ester gives a carboxylic acid which on Kolbes electrolysis yields ethane. The ester is :

• A. methyl ethanoate
• B. methyl methanoate
• C. ethyl methanoate
• D. methyl propanoate

Answer 1

Answer: (A)

Hydrolysis of $\text{C}{\text{H}}_{\text{3}}\text{COOC}{\text{H}}_{\text{3}}$ (methyl ethanoate) gives acetic acid and methyl alcohol. Acetic acid on electrolysis by Kolbes method gives ethane. So, the ester is methyl ethanoate. $\underset{\text{Methyl}\text{ethanoate}}{C{H}_{3}CO}OH\to$ $\underset{\text{Acetic}\text{acid}}{C{H}_{3}COOH+}C{H}_{3}OH$ Kolbes electrolysis: $\underset{\text{Acetic}\text{acid}}{C{H}_{3}COOH}\to C{H}_{3}CO{O}^{-}+H^{+}$ At anode:
or $\underset{(Ethane)}{C{H}_3-C{H}_3}$ At cathode: $H^{+}+e^{-}\to H$ $H+H\to H_2\uparrow$