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JEE Main levelSingle correct optionDifficulty 2 of 3pl017

In the free radical polymerisation of styrene, , a growing radical attacks a monomer molecule. The attack occurs

  1. Aat the carbon, giving a primary radical stabilised by hyperconjugation
  2. Bat the carbon, giving a benzylic carbocation
  3. Cat the carbon, giving a carbocation stabilised by the ring
  4. Dat the carbon, giving a benzylic radical stabilised by delocalisation into the ring

Answer: D

Addition at the less hindered end leaves the unpaired electron on the carbon bearing phenyl, a benzylic radical stabilised by resonance. The intermediate in radical polymerisation is a radical, not a cation.
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