Statement I: KCN reacts with methyl chloride to give methyl isocyanide as the main product.
Statement II: The cyanide ion (CN−) is an ambident nucleophile.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Statement I is incorrect but Statement II is correct.
An ambident nucleophile has two atoms that can donate an electron pair. The cyanide ion can bond to carbon of the alkyl group either through its carbon atom (giving an alkyl cyanide) or through its nitrogen atom (giving an alkyl isocyanide).
Statement I: KCN reacts with methyl chloride to give methyl isocyanide as the main product. — False. KCN is predominantly ionic and gives free cyanide ions. The attack takes place mainly through the carbon atom, because a C–C bond is more stable than a C–N bond, so the main product is methyl cyanide (ethanenitrile):
\( \displaystyle \ce{CH3Cl + KCN -> CH3CN + KCl} \)
An isocyanide is the main product with AgCN, which is mainly covalent.
Statement II: The cyanide ion (CN−) is an ambident nucleophile. — True. It has two nucleophilic centres, carbon and nitrogen.
NCERT (2026-27 edition):
Example 6.5 – “KCN is predominantly ionic and provides cyanide ions in solution. Although both carbon and nitrogen atoms are in a position to donate electron pairs, the attack takes place mainly through carbon atom and not through nitrogen atom since C—C bond is more stable than C—N bond.”
6.7.1 Reactions of Haloalkanes – “Groups like cyanides and nitrites possess two nucleophilic centres and are called ambident nucleophiles. Actually cyanide group is a hybrid of two contributing structures and therefore can act as a nucleophile in two different ways … i.e., linking through carbon atom resulting in alkyl cyanides and through nitrogen atom leading to isocyanides.”