JEE Main 2025 · 28 January · morning · Single correct · +4 / −1
The products A and B in the following reactions, respectively are
A ↔(Ag-NO₂) CH₃-CH₂-CH₂-Br →(AgCN) B
- (a) CH₃-CH₂-CH₂-ONO, CH₃-CH₂-CH₂-CN
- (b) CH₃-CH₂-CH₂-NO₂, CH₃-CH₂-CH₂-CN
- (c) CH₃-CH₂-CH₂-ONO, CH₃-CH₂-CH₂-NC
- (d) CH₃-CH₂-CH₂-NO₂, CH₃-CH₂-CH₂-NC
Answer and solution
Answer (d) CH₃-CH₂-CH₂-NO₂, CH₃-CH₂-CH₂-NC
Solution
Chemistry ma’am · 4 steps
With silver salts the bond to the metal is covalent, so the nucleophile attacks through N, not O or C.
- Ambident nucleophiles. Both NO₂⁻ and CN⁻ can attack through two different atoms. Nitrite can bond through N or O. Cyanide can bond through C or N.
- Silver nitrite. The Ag–O bond in AgNO₂ is largely covalent, so the free lone pair on nitrogen does the attacking. The product is the nitroalkane CH₃CH₂CH₂NO₂, so A is 1-nitropropane.
- Silver cyanide. In AgCN the carbon is held by a covalent Ag–C bond, so only the lone pair on nitrogen is free to attack. The product is the isocyanide CH₃CH₂CH₂NC, so B is propyl isocyanide.
Reagent Nature of bond Attacking atom Product KNO₂ ionic O alkyl nitrite, R-ONO AgNO₂ covalent N nitroalkane, R-NO₂ KCN ionic C alkyl cyanide, R-CN AgCN covalent N isocyanide, R-NC - So. A is CH₃CH₂CH₂NO₂ and B is CH₃CH₂CH₂NC, which is option (d).
The idea to keep. Potassium salts are ionic and give R-ONO and R-CN. Silver salts are covalent and give R-NO₂ and R-NC. With silver, think N for both.
Answer from the NTA final answer key. Solution by PrepWiser.