1. Case Western Reserve University
Chapter 4
Reactions of
Alkenes
Organic Chemistry
4th Edition
Paula Yurkanis Bruice
Irene Lee
Case Western Reserve University
Cleveland, OH
©2004, Prentice Hall

2. Electrophilic Addition of Alkenes

3. Addition of Hydrogen Halides

4. What is the product?

5. Carbocation formation is the rate-limiting step
a more stable
carbocation

6. Carbocation Stabilities

7. Alkyl groups decrease the concentration of positive
charge in the carbocation

8. Delocalization of Electrons

9. Molecular Orbital Diagram in a Hyperconjugation System

10. Hammond postulate: the transition state will be more
similar to the species that it is closer to energetically
Exergonic reaction: early transition state
Endergonic reaction: late transition state

11. I: early transition state
III: later transition state
II: mid-transition state

12. Reaction Rate and DG‡ more stable transition state lower DG‡
faster reaction rate

13. Markovnikov’s Rule
The electrophile adds to the sp2 carbon that is bonded to the greater number of hydrogens
In a regioselective reaction, one constitutional isomer is the
major or the only product

14. tert-Butyl cation is formed faster and it is more stable

15. Addition of Water to Alkene

16. Hydration of Propene

17. Acid-Catalyzed Addition of Alcohol

18. Rearrangement of Carbocation
1,2-hydride shift
a more stable
carbocation

19. Rearrangement of Carbocation
a more stable
carbocation
1,2-methyl shift

20. Carbocation does not always rearrange …

21. Carbocation Rearrangement
Ring Expansion
a more stable
carbocation

22. Addition of Halogens to Alkene

24. in the Presence of Water
Addition of Halogens
in the Presence of Water

25. Consider the transition states …

26. Oxymercuration and Mercuration
of Alkene

27. Demercuration by Reduction

28. Hydroboration–Oxidation
Addition of Borane
Hydroboration–Oxidation
Anti-Markovnikov’s rule in product formation

29. Anti-Markovnikov
addition
Markovnikov
addition
(a pericyclic reaction)

30. Formation of Alkyl Boranes

31. OH Replacement of Boron

32. Anti-Markovnikov Addition
of an OH Group

33. Reaction of Carbene with Alkene

34. Synthesis of Bromobutane

35. Generation of Radicals

36. Addition of Radicals to Alkene

37. Relative Stabilities of Alkyl Radicals

38. Calculating the Change in H°

39. Addition of Hydrogen to Alkenes

40. Catalytic Hydrogenation of an Alkene

41. Potential Energies of Pentene Isomers

42. Relative Stabilities of Alkenes

43. Steric Strain in Alkenes

44. Relative Stabilities of Dialkyl-Substituted Alkenes