Question: 85. Identify the major product C formed in the following reaction sequence:
\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{I} \xrightarrow{\mathrm{NaCN}} \mathrm{A} \xrightarrow[\text { Partial hydrolysis }]{\mathrm{OH}^{-}} \mathrm{B} \xrightarrow[\mathrm{Br}_{2}]{\mathrm{NaOH}} \underset{\text { (Major) }}{\mathrm{C}}(1) propylamine
(2) butylamine
(3) butanamide
(4) \alpha – bromobutanoic acid
Answer: Option (1)
Explanation:
In the first step, \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{I}
reacts with \mathrm{NaCN} via nucleophilic substitution to form a nitrile.
The carbon chain increases by one carbon,
giving \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CN},
which is butanenitrile.
In the second step, partial hydrolysis of the nitrile with \mathrm{OH}^{-}
converts it into the corresponding amide, forming butanamide.
In the final step, butanamide reacts with \mathrm{Br}_{2}
and \mathrm{NaOH} via the Hofmann bromamide reaction.
In Hofmann bromamide reaction, an amide is converted into a primary amine with one carbon less than the original amide.
Thus, butanamide gives propylamine as the major product.
Therefore, the major product C is propylamine.