1. Case Western Reserve University
Chapter 20
More About
Oxidation–Reduction
Reactions
Organic Chemistry
4th Edition
Paula Yurkanis Bruice
Irene Lee
Case Western Reserve University
Cleveland, OH
©2004, Prentice Hall

2. Oxidation is always coupled with reduction
Loss of electrons is oxidation
Gain of electrons is reduction
The oxidation state of a carbon atom equals the total
number of its C–O, C–N, and C–X bonds

4. Hydrogen, sodium borohydride, and hydrazine are the
reducing agents

5. Bromine and chromic acid are the oxidizing agents

6. H2 as a Reducing Agent

7. Reduction by Catalytic Hydrogenation

11. Dissolving-Metal Reduction

12. Reduction by Addition of a Hydride Ion and a Proton

13. LiAlH4 is a stronger reducing agent than NaBH4
LiAlH4 is used to reduce compounds that are nonreactive toward NaBH4

14. DIBAL allows the addition of one equivalent of hydride to
an ester
Replacing some of hydrogens of LiAlH4 with OR groups
decreases the reactivity of the metal hydride

15. Formation of Amines by Reduction

16. NaBH4 can be used to selectively reduce an aldehyde or
a keto group in a compound

17. Oxidation of Alcohols

18. Oxidation of a Primary Alcohol

19. Mechanism of Alcohol Oxidation by Chromic Acid

20. The oxidation of a primary alcohol can be stopped at the
aldehyde if pyridinium chlorochromate (PCC) is used
as the oxidizing agent

21. The Swern Oxidation

22. Mechanism of the Swern Oxidation

23. Oxidation of Aldehydes and Ketones

24. The Tollens Reagent Oxidizes Only Aldehydes

25. Both aldehydes and ketones can be oxidized by peroxyacid: The Baeyer–Villiger oxidation

27. Baeyer–Villiger Oxidation
Mechanism of the
Baeyer–Villiger Oxidation

28. Therefore, the product of the Baeyer–Villiger oxidation of
cyclohexyl methyl ketone will be cyclohexyl acetate,
because a secondary alkyl group is more likely to migrate
than a methyl group

29. Oxidation of Alkenes with Peroxyacids

30. Mechanism of Epoxidation of an Alkene

31. The addition of oxygen to an alkene is a stereospecific
reaction

32. Hydroxylation of Alkenes

33. Mechanism for cis-Glycol Formation

34. Higher yields of the diol are obtained with osmium
tetroxide

35. Oxidative Cleavage of 1,2-Diols

36. Oxidative Cleavage of Alkenes by Ozonolysis

37. The alkene and ozone undergo a concerted cycloaddition
Mechanism of ozonide formation
The molozonide is unstable because it has two O–O
bonds
Ozonide is stable

38. Ozonides can be cleaved to carbonyl compounds

39. Examples of the Oxidative Cleavage of Alkenes by Ozonolysis

41. A peroxyacid, OsO4, and (cold basic) KMnO4 break only
the p bond of the alkene
Ozone and acidic KMnO4 break both the p bond and the
s bond

42. Table 20.1 Summary of the Methods Used to Oxidize an Alkene

43. Oxidative Cleavage of Alkynes

44. Conversion of an Aldehyde into Other Functional Groups

45. Conversion of a Ketone into
an Ester or an Alcohol

46. Biological Oxidation–Reduction Reactions

48. NAD+ oxidizes ethanol by accepting a hydride ion

49. NADH reduces a carbonyl compound by donating a
hydride ion