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JEE Main levelSingle correct optionDifficulty 2 of 3nc241

Potassium phthalimide fails to give the amine from the halide shown by the Gabriel route. What is the main reason?

  1. APhthalimide anion is too weak a nucleophile to attack any halide
  2. BThe halogen is a poor leaving group only in alkyl halides, but chloride would work
  3. CThe carbon-halogen bond is on an sp2 carbon, so it does not undergo SN2 attack by the phthalimide anion
  4. DThe ring is deactivated towards electrophiles

Answer: C

The compound shown is bromobenzene. The Gabriel synthesis needs an SN2 displacement at an sp3 carbon. The aryl C-Br bond has partial double-bond character and the ring blocks backside attack, so aniline cannot be prepared this way.
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