Haloalkanes and Haloarenes · Question 23

The products A and B in the following reactions, respectively are A AgNO2 CH3-CH2-CH2-Br AgCN B

1. CH3-CH2-CH2-ONO, CH3-CH2-CH2-CN
2. CH3-CH2-CH2-NO2, CH3-CH2-CH2-CN
3. CH3-CH2-CH2-ONO, CH3-CH2-CH2-NC
4. CH3-CH2-CH2-NO2, CH3-CH2-CH2-NC

Answer

(4) CH3-CH2-CH2-NO2, CH3-CH2-CH2-NC

Solution

AgNO2 and AgCN are mainly covalent, so the attack takes place through the atom that carries the free lone pair, not through the negatively charged atom of the free ion.

In Ag–O–N=O the lone pair on nitrogen attacks nitroalkane is formed:

CH3CH2CH2Br + AgNO2 CH3CH2CH2NO2 (A) + AgBr

In Ag–C≡N the lone pair on nitrogen attacks isocyanide is formed:

CH3CH2CH2Br + AgCN CH3CH2CH2NC (B) + AgBr

(KCN and KNO2, being ionic, would give the nitrile and the alkyl nitrite instead.)

Answer: (4)