Question

Name the product obtained when ethyl cyanide is treated with dilute Hydrochloric acid?

Answer 1

Hint: Ethyl cyanide or propane nitrile according to IUPAC naming system or propionitrile is a simple aliphatic nitrile having a molecular formula $ C{H_3}C{H_2}CN $ . Ethyl cyanide is water soluble and colourless liquid. Ethyl cyanide can be prepared by dehydration of propionamide or by distillation of potassium cyanide and ethyl sulphate moreover ethyl cyanide is a byproduct of the electro dimerisation of acrylonitrile to adiponitrile.

Complete answer:
Hydrochloric acid, a strong acid, is an aqueous solution of hydrogen chloride which is also known as muriatic acid is a colourless solution having a distinctive pungent smell. Hydrochloric acid is a Bronsted-Lowry acid because it is a proton donor.
When a nitrile is heated under reflux with dilute hydrochloric acid the product obtained is a free carboxylic acid and the by-product is ammonium chloride. The free carboxylic acid formed can be distilled off the product mixture.
Therefore, if ethyl cyanide or propane nitrile or propionitrile is heated under reflux with dilute hydrochloric acid the product obtained would be propionic acid which contains carboxyl group attached to a propyl group with molecular formula $ $ $ C{H_3}C{H_2}COOH $ .
 $ C{H_3}C{H_2}CN + HCl + 2{H_2}O \to C{H_3}C{H_2}COOH + N{H_4}Cl $ .

Note:
There are two ways of converting the nitrile into a carboxylic acid one is by acid hydrolysis i.e. when nitrile is heated under reflux with dilute acid a carboxylic acid is formed the another method is by alkaline hydrolysis where nitrile is heated under reflux with an alkali the product obtained will be carboxylate ion moreover to convert the ion into a free carboxylic acid the reaction medium needs to be supplied with hydrogen ion from a strong acid.