Question

Which reagent is used to convert Alkyl halide into Alkyl nitrite ?

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

Hint:

Ionic KNO2 attacks through oxygen, giving R-O-N=O (alkyl nitrite).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The nitrite ion, \(\text{NO}_2^-\), is an ambident nucleophile. It can attack through oxygen to give an alkyl nitrite or through nitrogen to give a nitroalkane.

Step 2: Key Rule:
Ionic salts such as KNO2 and NaNO2 are largely ionic, so the more electronegative oxygen, which carries the free negative charge, attacks the carbon. Covalent salts such as \(\text{AgNO}_2\) attack through nitrogen, because the nitrogen lone pair is available.

Step 3: Detailed Explanation:
\[ \text{R-X} + \text{KNO}_2 \rightarrow \text{R-O-N=O} + \text{KX} \]
The product is an alkyl nitrite. With \(\text{AgNO}_2\) the product would be a nitroalkane, \(\text{R-NO}_2\).

Step 4: Why the other options are wrong.
Silver nitrite (A) gives the nitro compound. Silver cyanide (B) gives isocyanides (via N attack). Silver carboxylate (D) gives esters, \(\text{RCOOR}\).

Final Answer:
Potassium nitrite gives the alkyl nitrite, option (C). \[ \boxed{\text{Potassium nitrite (C)}} \]