Question

Which alkyl halides form the carboxylic acids listed hereafter reaction with sodium cyanide followed by heating the product in an acidic aqueous solution?

a. butyric acid

b. isovaleric acid

c. cyclohexane carboxylic acid

Short answer

Cyanide or nitrile on slow hydrolysis leads to the formation of carboxylic acids but in hard conditions leads to the formation of amides and the reaction is proceed in the presence of water and acid.

Step-by-step solution

Acid-catalyzed nitrile

Cyanide or nitrile on slow hydrolysis leads to the formation of carboxylic acids but in hard conditions leads to the formation of amides and the reaction is proceed in the presence of water and acid.

Formation of butyric acid

The reaction is followed by^SN² mechanism in which the alkyl halide reacts with the cyanide and the replacement of the halide ion from the nitrile ion occurs which on further reaction with acid and water leads to oxidation and formation of carboxylic occur as shown below:

Formation of isovaleric acid

For the formation of isovaleric acid the isovaleric nitrile is formed from the alkyl halide so, on reaction with 2-methyl bromopropane with cyanide leads to the formation of 2-methyl propane nitrile which on reaction with hydrochloric acid in presence of water formation of 2methyl propanoic acid called as isovaleric acid is formed as shown below:

Formation of cyclohexane carboxylic acid

It is formed on reaction of the cyclohexane nitrile in presence of water and acid and the cyclohexane nitrile is formed by cyclohexane bromide on reacting with cyanide in presence of DMSO as shown: