Assertion (A) : Diazonium salts of aromatic amines are more stable than those of aliphatic amines.
Reason (R) : Diazonium salts of aliphatic amines undergo resonance.
Reason (R) : Diazonium salts of aliphatic amines undergo resonance.
Show Hint
Aliphatic diazonium salts are so unstable they are never isolated; they just bubble off \( N_{2} \) gas.
- Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
- Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
- Assertion (A) is true, but Reason (R) is false.
- Assertion (A) is false, but Reason (R) is true.
The Correct Option is C
Solution and Explanation
• Diazonium salts have the general formula \( R-N_{2}^{+} X^{-} \).
• The stability of these salts depends on whether \( R \) is an alkyl (aliphatic) or aryl (aromatic) group.
• Stability in organic chemistry is often provided by the delocalization of charge through resonance.
Step 1: Analyze Aromatic Diazonium Salts
In benzenediazonium chloride, the positive charge on the nitrogen atom is dispersed over the benzene ring through resonance.
The \( \pi \)-electrons of the ring interact with the diazonium group, providing temporary stability at low temperatures (\( 0-5^\circ C \)).
Thus, Assertion (A) is true.
Step 2: Analyze Aliphatic Diazonium Salts
Aliphatic diazonium salts (\( R-N_{2}^{+} X^{-} \)) where \( R \) is an alkyl group (like methyl or ethyl) do not have a \( \pi \)-system to allow resonance.
The alkyl group only has a +I effect, which cannot stabilize the positive charge effectively.
As a result, they are extremely unstable and decompose instantly, even at very low temperatures, to release Nitrogen gas (\( N_{2} \)) and form carbocations.
Step 3: Evaluate the Reason
The Reason states that aliphatic diazonium salts undergo resonance.
As established in Step 2, alkyl groups lack the necessary conjugated system for resonance.
Therefore, Reason (R) is false.
Step 4: Final Verdict
Since the Assertion is a correct factual statement and the Reason is scientifically incorrect, the code is (C). The final answer is (C).
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