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JEE Main levelSingle correct optionDifficulty 2 of 3g3140

In electrophilic nitration of anisole () the substitution occurs mainly at the ortho and para positions. In terms of the Hammond postulate this is because

  1. Athe transition state resembles the final nitroanisole product
  2. Bits transition state resembles anisole itself, so the oxygen lone pair is irrelevant
  3. Cthe rate-determining formation of the arenium ion is endothermic, so its transition state resembles the arenium ion, which is stabilised by the oxygen lone pair for ortho/para attack
  4. Dthe arenium ion for meta attack is stabilised by the oxygen lone pair

Answer: C

Attack of the electrophile on the ring is endothermic and the transition state is late, similar to the arenium ion. Ortho and para attack give arenium ions with a resonance structure in which oxygen carries the positive charge. Meta attack gives no such structure. So factors that stabilise the arenium ion lower the transition state for ortho/para attack.
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