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JEE Main levelSingle correct optionDifficulty 2 of 3o4077

1-Bromobutane gives mainly butyl ethyl ether with /ethanol but mainly but-1-ene with /. The best explanation is that

  1. Athe alkene but-1-ene is more stable than butyl tert-butyl ether
  2. Bthe bulky tert-butoxide cannot easily attack the alpha carbon (SN2) but can remove a peripheral beta hydrogen
  3. Ctert-butoxide is a weaker base than ethoxide, so it does not attack carbon
  4. Dtert-butanol is a polar aprotic solvent and favours elimination

Answer: B

SN2 needs close approach to the alpha carbon, which is blocked for the bulky tert-butoxide. Proton abstraction occurs at the peripheral beta hydrogen and is much less sensitive to steric hindrance. Hence the bulky base shifts a primary halide from substitution to E2.
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