Assertion (A) : Aromatic primary amines can be prepared by Gabriel Phthalimide synthesis.
Reason (R) : Aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.
Reason (R) : Aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.
Show Hint
- 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 D
Solution and Explanation
Gabriel synthesis works well for primary aliphatic amines (like methylamine, ethylamine). However, it cannot be used to prepare primary aromatic amines like aniline (\(\text{C}_6\text{H}_5\text{NH}_2\)). Therefore, the Assertion is False.
Step 2: Analyzing the chemical reason (Reason).
To make aniline, we would need to react potassium phthalimide with an aryl halide (e.g., chlorobenzene). Aryl halides are extremely unreactive toward nucleophilic substitution because:
• The \( \text{C}-\text{X} \) bond has partial double bond character due to resonance.
• The carbon attached to the halogen is \(sp^2\) hybridized (more electronegative).
• Electronic repulsion between the nucleophile and the electron-rich benzene ring.
Consequently, the phthalimide anion cannot displace the halogen from the benzene ring. Thus, the Reason is True.
Step 3: Conclusion.
Assertion is False and Reason is True. This corresponds to option (D). Final Answer: (D) Assertion (A) is false, but Reason (R) is true.
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