Benzyl chloride is treated with sodium cyanide and the product is then reduced with hydrogen in the presence of nickel. The final product is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → C6H5CH2CH2NH2
The cyanide ion replaces the chlorine and adds one carbon atom to the chain; reduction then turns the –C≡N group into a –CH2NH2 group.
Step 1 – Substitution by cyanide: benzyl chloride gives phenylethanenitrile (benzyl cyanide).
\( \displaystyle \ce{C6H5CH2Cl + NaCN -> C6H5CH2CN + NaCl} \)
Step 2 – Reduction of the nitrile: the nitrile is reduced to a primary amine, 2-phenylethanamine.
\( \displaystyle \ce{C6H5CH2CN + 2H2} \xrightarrow{\ce{Ni}} \ce{C6H5CH2CH2NH2} \)
Why the other options are incorrect
Option (1) C6H5CH2COOH — Incorrect. This acid forms when the nitrile is hydrolysed, not when it is reduced with H2/Ni.
Option (3) C6H5NH2 — Incorrect. Aniline has the nitrogen on the ring and no side-chain carbon; neither step removes carbon atoms.
Option (4) C6H5CH2NH2 — Incorrect. Benzylamine has the same number of carbons as benzyl chloride; the cyanide route gives an amine with one carbon more.
NCERT (2026-27 edition):
9.4 Preparation of Amines – “3. Reduction of nitriles
Nitriles on reduction with lithium aluminium hydride (LiAlH4) or catalytic hydrogenation produce primary amines. This reaction is used for ascent of amine series, i.e., for preparation of amines containing one carbon atom more than the starting amine.”