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JEE Main levelSingle correct optionDifficulty 2 of 3o4023

Trans-1-tert-butyl-4-chlorocyclohexane and cis-1-tert-butyl-4-chlorocyclohexane are each treated with in ethanol. The tert-butyl group is so large that it stays equatorial in both. Which statement is correct?

  1. Aneither reacts by E2; both give only substitution products
  2. Bthe trans isomer eliminates much faster because its chlorine is equatorial
  3. Cboth react at the same rate because both lose HCl by E2
  4. Dthe cis isomer eliminates much faster because its chlorine is axial

Answer: D

E2 needs the chlorine axial, with an axial anti H on the adjacent carbon. With tert-butyl equatorial, the cis isomer has Cl axial and reacts readily, whereas in the trans isomer Cl is equatorial and cannot be anti to a ring H without ring flip, which is prevented. So the cis isomer eliminates much faster.
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