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JEE Main levelSingle correct optionDifficulty 2 of 3o3085

Towards in the corresponding alcohol, ethoxide is a better nucleophile than tert-butoxide even though tert-butoxide is the stronger base. This is because

  1. Atert-butoxide is a less polarisable anion because it contains no oxygen
  2. Bthe bulky tert-butyl group hinders attack at carbon much more than it hinders removal of a proton
  3. Ctert-butoxide is a weaker base in the gas phase
  4. Dethoxide is more strongly stabilised by hydrogen bonding

Answer: B

Nucleophilicity is a kinetic property that is sensitive to steric hindrance at the attacking atom, whereas basicity concerns attack on the small proton. tert-Butoxide is bulky, so it adds to a carbon centre slowly, while it can still remove a proton easily. That is why it is used as a base, not a nucleophile.
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