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Keto-enol tautomerization

Keto-enol tautomerization. enolization “normal” aldehydes and ketones K eq = ~ 10 -8. Stabilized aldehydes and ketones.  -diketones K eq = ~ 10. Mechanism for acid-catalyzed enolization. Mechanism for acid-catalyzed enolization. Reactions of enols:  -halogenation. An example.

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Keto-enol tautomerization

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  1. Keto-enol tautomerization • enolization • “normal” aldehydes and ketones • Keq = ~ 10-8

  2. Stabilized aldehydes and ketones • -diketones • Keq = ~ 10

  3. Mechanism for acid-catalyzed enolization

  4. Mechanism for acid-catalyzed enolization

  5. Reactions of enols: -halogenation

  6. An example

  7. An example

  8. Mechanism of -halogenation

  9. -Bromination of Acids: the HVZ Reaction

  10. The HVZ Reaction

  11. Acidity of carbonyl compounds • enolate ion formation • pKa = ~ 16-20

  12. Base-catalyzed enolization

  13. Ester Enolates • pKa = ~22

  14. Alkylation of ester enolates

  15. Alkylation of ester enolates

  16. Alkylation of ester enolates

  17. Alkylation of ester enolates

  18. Alkylation of ester enolates

  19. Reactions of enolates: • The Aldol Condensation

  20. Aldol Condensation

  21. More Aldol Condensation

  22. Formation of -unsaturated carbonyls

  23. An example

  24. An example

  25. Claisen-Schmidt condensation

  26. Claisen-Schmidt condensation

  27. Examples

  28. Nucleophilic Addition to -Unsaturated Carbonyls

  29. Michael Addition

  30. Michael Addition

  31. Robinson Annulation

  32. Robinson Annulation

  33. Michael Addition

  34. Michael Addition

  35. Robinson Annulation

  36. Robinson Annulation

  37. The Claisen condensation

  38. The Claisen condensation

  39. An example

  40. The product

  41. Another example

  42. Another product

  43. The Dieckmann condensation

  44. The Dieckmann condensation

  45. Decarboxylation of Malonic Acids and b-Ketoacids • Malonic acid Acetoacetic acid

  46. Decarboxylation of Malonic Acids and b-Ketoacids

  47. Ketone acylation using esters

  48. Ketone acylation using esters

  49. Ketone acylation using esters

  50. Acetoacetic ester synthesis of ketones • ethyl acetoacetate

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