Question

Identify the reagent used in following conversion.
$\text{Chloroethane} \xrightarrow{\text{A}} \text{Nitro ethane}$

• A. Sodium nitrite
• B. Silver nitrite
• C. Potassium nitrite
• D. Potassium cyanide

Hint:

Remember this classic pair configuration for ambident nucleophiles: 1. To introduce a true Carbon-Nitrogen bond ($\mathrm{-NO}_2$), use covalent Silver nitrite ($\mathrm{AgNO}_2$). 2. To introduce a Carbon-Oxygen bond ($\mathrm{-ONO}$), use ionic Potassium/Sodium nitrite ($\mathrm{KNO}_2/\mathrm{NaNO}_2$).

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
Choose reagent 'A' to convert chloroethane (CH₃CH₂Cl) into nitroethane (CH₃CH₂NO₂).

Step 2: Key Formula or Approach:
Nitrite ion (NO₂⁻) is ambident, attacking via N (nitro) or O (nitrite). Product depends on whether the reagent is ionic or covalent.

Step 3: Detailed Explanation:
Ionic NaNO₂/KNO₂ dissociate completely; the O atom with high negative charge attacks, giving alkyl nitrite (CH₃CH₂-O-N=O). Covalent AgNO₂ has a strong Ag-O bond; the N lone pair attacks instead, yielding nitroalkane: CH₃CH₂Cl + AgNO₂ → CH₃CH₂NO₂ + AgCl↓.

Step 4: Final Answer:
Required reagent is silver nitrite (AgNO₂), option (B).