Chapters 18 and 23: Reactions at the α-Position of Aldehydes, Ketones and Carboxylic Acid Derivatives

  1. You know that a carbonyl group (ketone, aldehyde, ester) will make the α-proton weakly acidic.
  2. You know that tautomerization of the α-proton creates an enol, and loss of this proton creates an enolate anion.
  3. You understand the quantitative relationship between the pKa of the α-proton, the pKa of the enol hydroxyl group, and the equilibrium constant for tautomerization.
  4. You recognize the nucleophilic character of an enol or enolate anion, and the function of each group in the following reactions:
    • α-Halogenation
    • The haloform reaction
    • The Hell-Volhard-Zelinsky reaction (Section 19-12)
    • Alkylation with alkyl halides
  5. You recognize the similarity between an enol and an enamine, and know how an enamine can be used as a nucleophile in alkylation.
  6. You know how an enamine is made from a carbonyl compound and a secondary amine. (see also Chapter 17)
  7. You know the mechanism for the aldol condensation, the function of the carbonyl compound as both nucleophile and electrophile, and the importance of using a comparatively weak base or acid to catalyze the reaction.
  8. Given an α, β-unsaturated carbonyl compound, you can specify the ketone(s) or aldehyde(s) required to make it via an aldol condensation.
  9. You understand the inherent problems with performing a "cross aldol" condensation, and know what situations allow such a reaction to succeed.
  10. You understand the benefits of using aldol chemistry to form rings.
  11. You understand how the carbonyl group affects the double bond in an α, β-unsaturated carbonyl compound, and why Michael addition occurs with some (but not all) nucleophiles.
  12. You understand the parallels and the differences between the aldol condensation and the Claisen condensation.
  13. You understand the reactions involved in the malonic and acetoacetic ester syntheses, and can suggest appropriate reactants to use in order to employ these reactions to make complex molecules.
  14. You understand the mechanism of the Robinson annulation, and can suggest the proper combination of ketone and α, β-unsaturated carbonyl compound needed to make a cyclohexenone via this reaction.
Recommended problems: 
18.32    18.36    18.37    18.45    18.51    18.59     18.61
23.27    23.28    23.30    23.34    23.40    23.45    23.49