Question

Which from following reagents is used to prepare alkyl isocyanides from RX?

• A. AgCN (alco)
• B. \(\text{NH}_3\) (alco)
• C. \(\text{KNO}_2\)
• D. \(\text{AgNO}_2\)

Hint:

Silver cyanide is covalent, so the nitrogen end attacks the carbon and gives the isocyanide.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The cyanide ion is an ambident nucleophile, meaning it can attack through carbon or through nitrogen. Ionic cyanides (KCN) attack through carbon and give nitriles. Covalent AgCN attacks through nitrogen.

Step 2: Detailed Explanation:
\[ \text{R-X} + \text{AgCN} \to \text{R-NC} + \text{AgX} \]
So alcoholic silver cyanide gives alkyl isocyanide.

Step 3: Why the other options are wrong.
Alcoholic \(\text{NH}_3\) gives amines. \(\text{KNO}_2\) gives alkyl nitrite mainly, and \(\text{AgNO}_2\) gives nitroalkane.

Final Answer:
The reagent is alcoholic AgCN, option (A). \[ \boxed{\text{AgCN (alco)}} \]