Question

In the below sequence of reactions A and B are which of the following ?
$(C{H}_3{)}_{2}CO\underset{HCl}{\overset{NaCN}{\to }}A\underset{△}{\overset{H_3{O}^{+}}{\to }}B$

• A. $\left(C{H}_3{)}_{2}C\right(OH)CN,(C{H}_3{)}_{2}C\left(OH\right)COOH$
• B. $\left(C{H}_3{)}_{2}C\right(OH)CN,(C{H}_3{)}_{2}C(OH{)}_2$
• C. $\left(C{H}_3{)}_{2}C\right(OH)CN,(C{H}_3{)}_{2}CHCOOH$
• D. $\left(C{H}_3{)}_{2}C\right(OH)CN,(C{H}_3{)}_{2}C=O$

Answer 1

The correct option is A $\left(C{H}_3{)}_{2}C\right(OH)CN,(C{H}_3{)}_{2}C\left(OH\right)COOH$

Converting the nitrile into a carboxylic acid
There are two ways of doing this, both of which involve reacting the carbon-nitrogen triple bond with water. This is described as hydrolysis.
Acid hydrolysis:
The nitrile is heated under reflux with a dilute acid such as dilute hydrochloric acid. A carboxylic acid is formed. For example, starting from ethanenitrile you would get ethanoic acid.
Base hydrolysis:
The nitrile is heated under reflux with an alkali such as sodium hydroxide solution.
Mechanism:
The reaction passes through an amide intermediate.
Both acid and base catalyzes the hydrolysis reaction.
In the first step, the $C{N}^{-}$ undergoes nucleophilic addition reaction with ketone to form cyanohydrin. in the second step, cyano group is hydrolyzed to carboxylic group in acidic medium (Z).
In the below sequence of reactions A and B are shown below