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JEE Main levelSingle correct optionDifficulty 2 of 3o3138

trans-2-Acetoxycyclohexyl tosylate solvolyses in acetic acid about a thousand times faster than the cis isomer. The best explanation is that in the trans isomer

  1. Athe trans isomer undergoes E2 elimination, which is faster than substitution
  2. Bthe acetoxy carbonyl oxygen can attack the carbon bearing OTs from the back in the diaxial conformer, while in the cis isomer this backside approach is impossible
  3. Cthe acetoxy group is more electron-withdrawing in the trans arrangement
  4. Dthe cis isomer is more stable and hence less reactive

Answer: B

Anchimeric assistance needs the participating oxygen to approach the reacting carbon from the side opposite to the leaving group, i.e. a trans-diaxial arrangement. The trans isomer can adopt it; the cis isomer cannot because one substituent is always equatorial. The cis isomer thus reacts only by the slower unassisted route.
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