Statement I: KCN reacts with methyl chloride to give methyl isocyanide

Statement II: CN⁻ is an ambidentate nucleophile

Statement I is false but statement II is correct

The correct answer is option 4. statement I is false but statement II is correct.

Let us break down the statements and their details:

Statement I: KCN reacts with methyl chloride to give methyl isocyanide

Reaction Overview:

Potassium Cyanide (KCN): When KCN reacts with methyl chloride (CH₃Cl), the primary product is methyl cyanide (acetonitrile), not methyl isocyanide.

Reaction: The reaction between KCN and CH₃Cl is:

\(\text{KCN} + \text{CH}_3\text{Cl} \rightarrow \text{CH}_3\text{CN} + \text{KCl}\)

Methyl Cyanide (CH₃CN): This is a nitrile where the cyano group (–C≡N) is attached to the methyl group. It is the usual product of this reaction.

Methyl Isocyanide (CH₃NC):

Methyl isocyanide can be formed through a different reaction. Typically, methyl iodide (CH₃I) reacts with sodium cyanide (NaCN) to produce methyl isocyanide:

\(\text{CH}_3\text{I} + \text{NaCN} \rightarrow \text{CH}_3\text{NC} + \text{NaI}\)

The formation of methyl isocyanide from methyl chloride and KCN is not a common reaction under normal conditions.

Statement II: CN⁻ is an ambidentate nucleophile

Ambidentate Nature:

An ambidentate nucleophile is a nucleophile that can form bonds with different atoms in a molecule. In the case of CN⁻, it can act as a nucleophile through: The carbon in the cyano group (–C≡N) can attack an electrophile. The nitrogen in the cyano group can also act as a nucleophile. In certain reactions, CN⁻ can bind to metal centers through either the carbon or nitrogen. This dual possibility of binding through different atoms makes it an ambidentate nucleophile.

Summary

Statement I is incorrect because the reaction of KCN with methyl chloride produces methyl cyanide (acetonitrile), not methyl isocyanide. Statement II is correct because CN⁻ is an ambidentate nucleophile and can coordinate through either the carbon or nitrogen atom.

Thus, the correct evaluation is: Statement I is false but Statement II is correct..