Problems and exercisesAcid-Base Properties

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1. Keto-enol equilibria

Explain the shifts of the following keto-enol equilibria:

Table of seven carbonyl compounds with their enol form and the percentage of enol, from less than 10⁻⁷ for acetaldehyde to 100 for phenol

2. A chiral ketone in base

Could you predict what would happen to (S)-3-phenyl-2-butanone when treated with a base?

3. A cyclohexanone in base

Could you foretell what will happen to cis-2,5-dimethylcyclohexanone in basic medium?

cis-2,5-Dimethylcyclohexanone in the chair conformation, with the C2 methyl axial

4. Butanone in heavy water

What about butanone, if we dissolve it in deuterated water in basic medium?

5. Epimerization and deuteration

A few minutes after dissolving the pure trans diastereomer of 2-methyl-4-tert-butylcyclohexanone in aqueous ethanol containing a catalytic amount of NaOH, the cis isomer starts to appear and ends up being the major component of the mixture. Besides, when ethanol-d (CH₃CH₂OD) and NaOD are used, the same cis-trans mixture is obtained, but of 2,6,6-trideutero-2-methyl-4-tert-butylcyclohexanone. Propose a mechanism that explains these transformations.

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