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Understanding Alkene Addition Reactions: Synthesis and Mechanisms

Explore the synthesis, mechanisms, and stereochemistry of alkene addition reactions, including Markovnikov and Anti-Markovnikov additions, bromonium ion intermediates, hydroboration, oxymercuration, and cyclopropanation. Learn how to predict products and understand regiochemistry.

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Understanding Alkene Addition Reactions: Synthesis and Mechanisms

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  1. Alkenes Addition Reactions Synthesis

  2. Addition of HBr or HClMarkovnikov Addition

  3. HBr Addition with RO-ORAnti-Markovnikov

  4. Free-Radical Mechanism

  5. Addition of Br2

  6. A Similar Mechanism to the Addition of HBr?

  7. Trans is formed exclusively(No cis is formed)

  8. Carbocation can be Stabilized by Neighboring Br

  9. Bromonium Ion is Opened Equally from Both Sides

  10. Definitions • Stereospecific – only one stereoisomer is formed at the expense of the other (e.g. trans vs. cis) • Stereoselective – one stereoisomer is formed preferentially over the other.

  11. Anti-Addition Stereospecific ReactionAnti-addition

  12. Bromonium Ion Intermediate

  13. Halohydrins

  14. Bromohydrin FormationAddition of Br – OHStereospecific & Regiospecific

  15. Unsymmetrical Bromonium ionH2O opens ring at more hindered site

  16. Br and OH are trans in anti addition

  17. Catalytic Hydrogenationsyn addition

  18. Mechanism – Syn Addition

  19. Syn Addition of H2

  20. Hydrogenationall alkene p bonds are reduced

  21. Hydrogenated Vegetable Oil

  22. HydrationAddition of H2O

  23. Oxymercuration HydrationMarkovnikov additionRegiospecific Reaction

  24. Oxymercuration Mechanism

  25. Predict the Oxymercuration Hydration Products

  26. What Alkene would you use to Make These Alcohols?

  27. Hydroboration HydrationAnti-Markovnikov Syn addition

  28. BH3 adds to Alkene

  29. Hydroboration

  30. Regiochemistry is Anti-Markovnikov

  31. Syn Addition of H2O

  32. Draw the Major Products

  33. 2 Complementary Hydration Reactions

  34. Oxymercuration – the more highly substituted alcohol formsHydroboration– the less highly substituted alcohol forms

  35. Predict Both Oxymercuration and Hydroboration Products

  36. Cyclopropanation

  37. A Carbene is Similar to Geometry of a Carbocation

  38. Dichlorocarbene Reactions

  39. Simmons-Smith Reaction

  40. In situ Preparation of Carbene

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