Question

Assertion (A): Aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis. Reason (R): Gabriel phthalimide synthesis is used for the preparation of primary aliphatic amines.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false, but Reason (R) is true.

Hint:

Gabriel phthalimide synthesis prepares primary aliphatic amines, not aromatic amines.

Answer 1

The Correct Option is B

Concept:
Gabriel phthalimide synthesis is used to prepare primary aliphatic amines. It involves reaction of potassium phthalimide with alkyl halides followed by hydrolysis. This reaction requires nucleophilic substitution. Aryl halides do not undergo such substitution easily.

Step 1: Check the Assertion.
The assertion says that aromatic primary amines cannot be prepared by Gabriel phthalimide synthesis. This is true. Aryl halides like chlorobenzene do not undergo normal \(S_N2\) reaction with phthalimide ion.

Step 2: Check the Reason.
The reason says Gabriel phthalimide synthesis is used for preparation of primary aliphatic amines. This is also true. \[ R-X + \text{Potassium phthalimide} \rightarrow \text{N-alkyl phthalimide} \rightarrow RNH_2 \]

Step 3: Check whether Reason explains Assertion.
The exact reason aromatic amines cannot be prepared is that aryl halides do not undergo nucleophilic substitution easily because of partial double bond character in the \(C-X\) bond. The Reason states a true fact, but it does not fully explain the Assertion. Hence: \[ \boxed{\text{(B)}} \]