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JEE Main levelOne or more correct optionsDifficulty 2 of 3o4011

Which of the following statements about the E1 elimination of an alkyl halide is/are correct?

  1. AThe rate is independent of the concentration of the base.
  2. BA carbocation intermediate is formed, which may undergo a hydride or alkyl shift.
  3. CThe reaction occurs in one concerted step in which the beta-H and the leaving group must be anti-periplanar.
  4. DThe reaction is usually accompanied by SN1 substitution products.

Answer: A, B, D

E1: ionisation is rate determining so rate = ; the carbocation can rearrange and is also trapped by solvent (SN1 products). It is not a one-step reaction, so there is no requirement of anti-periplanar H and X in a concerted transition state.
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