Organic Chemistry 6 th Edition Paula Yurkanis Bruice

1. Chapter 18 Carbonyl Compounds II Reactions of Aldehydes and Ketones More Reactions of Carboxylic Acid Derivatives Reactions of a,b-Unsaturated Carbonyl Compounds Organic Chemistry 6th Edition Paula Yurkanis Bruice

2. Nomenclature of Aldehydes

3. If a compound has two functional groups, the one with the lower priority is indicated by its prefix:

4. Nomenclature of Ketones The carbonyl is assumed to be at the 1-position in cyclic ketones:

5. If a ketone has a second functional group of higher priority… A few ketones have common names:

6. The partial positive charge on the carbonyl carbon causes that carbon to be attacked by nucleophiles: An aldehyde has a greater partial positive charge on its carbonyl carbon than does a ketone:

7. Aldehydes Are More Reactive Than Ketones • Steric factors contribute to the reactivity of an aldehyde. • The carbonyl carbon of an aldehyde is more accessible • to the nucleophile. • Ketones have greater steric crowding in their transition • states, so they have less stable transition states.

8. The reactivity of carbonyl compounds is also related to the basicity of Y–:

9. Carboxylic acid derivatives undergo nucleophilic acyl substitution reactions with nucleophiles:

10. Aldehydes and ketones undergo nucleophilic addition reactions with nucleophiles: This is an irreversible nucleophilic addition reaction if the nucleophile is a strong base

11. A reversible nucleophilic addition reaction:

12. Formation of a New Carbon–Carbon Bond Using Grignard Reagents Grignard reagents react with aldehydes, ketones, and carboxylic acid derivatives

13. Grignard reagents are used to prepare alcohols:

14. Mechanism for the reaction of an ester with a Grignard reagent:

15. Examples of Grignard Reactions

16. + + NH3 Na Reaction of Acetylide Ions with Carbonyl Compounds

18. Mechanism for the reaction of an acyl chloride with hydride ion:

19. Mechanism for the reaction of an ester with hydride ion: Esters and acyl chlorides undergo two successive reactions with hydride ion and Grignard reagents

20. Utilization of DIBALH to Control the Reduction Reaction

21. The reduction of a carboxylic acid with LiAlH4 forms a single primary alcohol: Acyl chloride is also reduced by LiAlH4 to yield an alcohol

22. An amide is reduced by LiAlH4 to an amine Mechanism for the reaction of an N-substituted amide with hydride ion:

23. Hydride Reducing Agents

24. Selectivity of Reductions

25. Aldehydes and ketones react with a primary amine to form an imine: This is a pH-dependent nucleophilic addition–elimination reaction

26. Dependence of the rate of the reaction of acetone with hydroxylamine on the pH of the reaction: a pH-rate profile Maximum rate is at pH = pKa of +NH3OH; at this pH, both [H+] and [NH2OH] have the highest values Decreasing rate: [H+] is decreasing Decreasing rate: [NH2OH] is decreasing Composition of the rate- determining step:

27. Aldehydes and ketones react with secondary amines to form enamines: An enamine undergoes an acid-catalyzed hydrolysis to form a carbonyl compound and a secondary amine

28. Enamine Reactions

29. Formation of Imine Derivatives

30. Types of Amine–Carbonyl Addition Products

31. Reductive Amination

32. Deoxygenation of the Carbonyl Group Called the Wolff–Kishner reduction

33. Water adds to an aldehyde or ketone to form a hydrate:

34. Mechanism for acid-catalyzed hydrate formation:

35. Why is there such a difference in the Keq values?

36. The equilibrium constant for the reaction depends on the relative stabilities of the reactants and products:

37. Addition of an Alcohol to an Aldehyde or a Ketone

38. Mechanism for acid-catalyzed acetal or ketal formation:

39. The Wittig reaction is completely regioselective. • This reaction is the best way to make a terminal alkene. • Stable ylides form primarily E isomers, and unstabilized • ylides form primarily Z isomers. • Stable ylides have a group (C=O) that can share the • carbanion’s negative charge. Example:

40. Stereochemistry of Nucleophilic Addition Reaction

44. Disconnections, Synthons, and Synthetic Equivalents

45. Nucleophilic Addition to a,b-Unsaturated Aldehydes and Ketones

47. Nucleophiles that form unstable addition products form • conjugated addition products, because the conjugate • addition is not reversible. • Nucleophiles that form stable addition products can • form direct addition products or conjugate addition • products. • If the rate of direct addition is slowed down by steric • hindrance, a Grignard reagent will form the conjugate • addition product.

49. Strong bases form direct addition products with reactive carbonyl groups and conjugate addition products with less reactive carbonyl groups:

50. Weak bases form conjugate addition products: