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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3o4199

Neomenthyl chloride is the diastereomer of menthyl chloride in which, in the more stable chair, chlorine is axial while the isopropyl (on C2) and methyl (on C5) groups are equatorial. In menthyl chloride all three groups are equatorial in the more stable chair. Ring numbering: C1 bears Cl, C2 bears isopropyl, C5 bears methyl, and C6 is the between C1 and C5. Both compounds are treated with in ethanol. Which statements are correct?

  1. ANeomenthyl chloride undergoes E2 much faster than menthyl chloride.
  2. BMenthyl chloride gives mainly 1-isopropyl-4-methylcyclohexene.
  3. CMenthyl chloride gives only 3-isopropyl-6-methylcyclohexene.
  4. DNeomenthyl chloride gives mainly 1-isopropyl-4-methylcyclohexene.

Answer: A, C, D

Neomenthyl chloride has axial Cl in its stable chair, with axial H on both C2 and C6; it eliminates fast, and the C2 H gives the Saytzeff alkene 1-isopropyl-4-methylcyclohexene. In menthyl chloride Cl is equatorial. The reactive conformer needs all groups axial, where the C2 H is equatorial (not anti) and only the C6 H is anti, giving 3-isopropyl-6-methylcyclohexene exclusively and slowly.
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