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JEE Main levelOne or more correct optionsDifficulty 2 of 3o3132

Select the correct statement(s) about the SN2 reaction of an alkyl halide with an anionic nucleophile.

  1. APrimary alkyl halides react faster than tertiary alkyl halides because backside attack is less hindered.
  2. BFluoride is a stronger nucleophile in methanol than in DMSO because methanol stabilises the transition state.
  3. CThe rate depends on the concentrations of both the alkyl halide and the nucleophile.
  4. DA chiral secondary alkyl halide gives a racemic product because the nucleophile can attack either face.

Answer: A, C

The first two are correct: SN2 is bimolecular, so the rate is , and steric hindrance makes primary faster than tertiary. SN2 attacks only from the back and so gives inversion, not racemate. In methanol, hydrogen bonding strongly stabilises and lowers its nucleophilicity; it is more reactive in DMSO.
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