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JEE Advanced levelSingle correct optionDifficulty 3 of 3o4210

Heats of hydrogenation are: pent-1-ene , (Z)-pent-2-ene , (E)-pent-2-ene . Pentan-2-ol is dehydrated with conc. under conditions that favour the thermodynamically more stable alkene. The product abundance order is:

  1. A(E)-pent-2-ene (Z)-pent-2-ene pent-1-ene
  2. Bpent-1-ene (Z)-pent-2-ene (E)-pent-2-ene
  3. C(Z)-pent-2-ene (E)-pent-2-ene pent-1-ene
  4. D(E)-pent-2-ene pent-1-ene (Z)-pent-2-ene

Answer: A

A lower heat of hydrogenation means a more stable alkene. Stability order is (E)-pent-2-ene (116) (Z)-pent-2-ene (120) pent-1-ene (126). E1 dehydration is governed by Saytzeff orientation and product stability, so abundances follow the same order.
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