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JEE Advanced levelSingle correct optionDifficulty 3 of 3o2152

Electrophilic attack on anisole is faster at the para position than at the meta position mainly because

  1. Athe methoxy group is bulky and blocks the meta positions
  2. Bpara attack gives an arenium ion with a resonance contributor in which oxygen bears the positive charge and every atom has an octet
  3. Cpara attack avoids formation of an sp3 carbon
  4. Dthe meta arenium ion has the positive charge on the carbon bearing , which is stabilised

Answer: B

For ortho or para attack one contributor puts the positive charge on the carbon carrying , and the oxygen lone pair then gives an oxonium contributor with complete octets. In meta attack the charge is never on that carbon, so there is no such stabilisation. Sterics are not the reason, since the methoxy group does not block meta positions.
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