Question

How ethanoic acid can be prepared by ethanol or ethanenitrile?

Answer 1

Oxidation with dichromate under reflux, or in the case of nitrile, acid hydrolysis.

Explanation:

Ethanol can be refluxed with excess of potassium dichromate solution (oxidising agent) and dilute sulphuric acid (catalyst). You need to reflux because the ethanol will initially form acetaldehyde and you need to prevent this from volatilising away before it is fully oxidised to acetic acid, which can then be distilled off.

You can convert acetonitrile (ethanenitrile) to acetic acid by acid hydrolysis - reflux the nitrile with dilute hydrochloric acid, and you will form the acetic acid which can then be distilled off.