Question

The alkyl cyanides when hydrolysed to the corresponding acid, the gas evolved is
A. ${O_2}$
B. ${N_2}$
C. $N{H_3}$
D. $C{O_2}$

Answer 1

Hint: Alkyl cyanides or also known as alkyl nitriles have chemical formula $C{N^ - }$. Hydrolysis is made of two words that are hydro and lysis. Hydro means water and lysis means cleavage or breaking. Thus, hydrolysis means lysis or break down using hydro meaning water or aqua.

Complete step-by-step answer:Cyanide can be hydrolysed in basic medium as well as in acidic medium giving specific products following different reaction mechanisms to the product formation.
In acidic medium, alkyl cyanide is hydrolysed to give carboxylic acid as the main product of the reaction followed by formation of ammonia gas which being released in acidic medium takes up hydronium ion from acid to convert to ammonium cation \[N{H_4}^ + \].
In basic medium the hydrolysis of alkyl cyanides undergoes reaction to release carboxylate ion and ammonia gas. It is basically carboxylate and ammonia which get protonated in acidic medium and form carboxylic acid and ammonium cation as the products.
Thus, the gas released is ammonia having formula $N{H_3}$.

Option ‘C’ is correct

Note: In both the cases, it is amide which is first formed which gets converted into carboxylate ion followed by protonation to carboxylic acid. Firstly, nitrile gets converted to imidic acid which on keto-enol tautomerism forms amide. Then the amide is formed which undergoes proton transfer reactions to form carboxylic acid which is the main product of the reaction along with the release of ammonia gas.