Given below are two statements, one is labelled as Assertion (A) and other is labelled as Reason (R)
Assertion (A): Gabriel phthalimide synthesis cannot be used to prepare aromatic primary amines.
Reason (R): Aryl halides do not undergo nucleophilic substitution reaction.
In the light of the above statements, choose the correct answer from the options given below:
Assertion (A): Gabriel phthalimide synthesis cannot be used to prepare aromatic primary amines.
Reason (R): Aryl halides do not undergo nucleophilic substitution reaction.
In the light of the above statements, choose the correct answer from the options given below:
- (A)Both (A) and (R) are true and (R) is correct explanation of (A).✓ Correct
- (B)(A) is false but (R) is true.
- (C)(A) is true but (R) is false
- (D)Both (A) and (R) are true but (R) is not the correct explanation of (A).
Answer: (A)
Solution
Gabriel's synthesis works by letting the phthalimide anion displace halide from a carbon in a bimolecular nucleophilic substitution, the imide nitrogen later being freed by hydrolysis or by hydrazinolysis. In an aryl halide the carbon holding the halogen is hybridised and a lone pair of the halogen is delocalised into the ring, which shortens and strengthens the carbon-halogen bond, while the cloud of the ring repels an approaching nucleophile. Aryl halides therefore do not take part in such substitution under the conditions of the synthesis, and no aromatic primary amine can be built this way. Both the assertion and the reason are true, and the reason is the correct explanation of the assertion.
JEE Main · 2021 · 25 Jul 2021 · Shift 1 · Single correct option