MolSynapsequestion bank
MolSynapse / Question bank / General Organic Chemistry III: Reaction Intermediates / Carbanions and enolates
JEE Advanced levelOne or more correct optionsDifficulty 3 of 3g3082

Each of the following is stirred for a long time with excess in so that every alpha C-H exchanges (no other C-H bonds exchange). Which incorporate exactly three deuterium atoms per molecule?

  1. A3,3-Dimethylbutan-2-one,
  2. BAcetophenone,
  3. CPropiophenone,
  4. DCyclohexanone

Answer: A, B

Count the alpha hydrogens. Acetophenone has one alpha (3 H) and an aryl carbon with none, so 3. In 3,3-dimethylbutan-2-one the tert-butyl side has a quaternary carbon, so only the gives 3. Propiophenone has an alpha (2 H), and cyclohexanone has two alpha groups (4 H).
Practice General Organic Chemistry III: Reaction Intermediates More on Carbanions and enolates
Previous questionNext question

More questions on Carbanions and enolates