1 / 67

Chapter 7

Chapter 7. Alkene Synthesis & Reactions. sp 2  sp 3. p 172, Table 5.3. Diss. energy of double bond (H 2 C=CH 2 ): 611 kJ/mol. Diss. energy of sigma bond (CH 3 — CH 3 ): 376 kJ/mol. Dissociation energy of pi bond: 235 kJ/mol. Therefore, pi bond is more reactive than sigma bond. allylic

aspen
Download Presentation

Chapter 7

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 7 Alkene Synthesis & Reactions Chapter 7

  2. sp2 sp3 p 172, Table 5.3 Diss. energy of double bond (H2C=CH2): 611 kJ/mol Diss. energy of sigma bond (CH3 — CH3): 376 kJ/mol Dissociation energy of pi bond: 235 kJ/mol Therefore, pi bond is more reactive than sigma bond. Chapter 7

  3. allylic 361 kJ/mol Vinylic C—H 444 kJ/mol alkyl 401 kJ/mol General Properties No rotation about the pi bond. Relatively nonpolar. Not soluble in water, but soluble in hexane, ether, etc. p 172, Table 5.3 1. Radical reactions take place at the allylic position. 2. Allylic hydrogen is more acidic than alkyl and vinylic hydrogen. Chapter 7

  4. Alkene Synthesis Chapter 7

  5. Synthesis From halides - dehydrohalogenation (minus HX): Elimination From alcohol - dehydration (minus H2O): Chapter 7

  6. Elimination Reaction Chapter 7

  7. Answer Key Chapter 7

  8. Alkene Reactions Chapter 7

  9. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  10. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  11. Alkene + HX X: Cl, Br, or I. Carbocation intermediate - is planar, incoming group can attack from above or below the plane. Markovnikov rule - regiochemistry. Review Chapter 6. Chapter 7

  12. ? 2-Chloro-3-methylheptane Alkene + HX Electrophilic Addition. Chapter 7

  13. Answer Key Chapter 7

  14. Alkene + HX - suppliment Secondary halide - carbocation. Primary halide - free radical.   Chapter 7

  15. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  16. Alkene + X2 X: Cl or Br. F is too reactive, I does not react. Chloronium or bromonium ion intermediate. Anti stereochemistry. Chapter 7

  17. Alkene + X2 Chapter 7

  18. Answer Key trans-1,2,Dichloro-1,2-dimethylcyclohexane 1,2,Dibromopropane Chapter 7

  19. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  20. DMSO - solvent, NBS - source of Br2. Halohydrin Alkene  halohydrin. Form bromonium ion intermediate. Then attack by nucleophile. Aromatic ring is inert. Anti stereochemistry. Markovnikov rule applies. Chapter 7

  21. Halohydrin Chapter 7

  22. Answer Key 1-bromo-2-propanol trans-2-bromocyclopentanol or cyclopentene bromohydrin (E)-2-Chloro-1-methly-1-cyclopentanol Chapter 7

  23. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  24. Oxymercuration Alkene  alcohol. Intermediate is mercurinium ion (similar to bromonium ion). Anti stereochemistry. Markovnikov rule applies. Chapter 7

  25. Oxymercuration Chapter 7

  26. Answer Key Chapter 7

  27. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  28. Hydroboration Alkene  alcohol. Intermediate is organoborane. Syn stereochemistry. Non - Markovnikov rule applies. Chapter 7

  29. Hydroboration Mechanism Chapter 7

  30. Hydroboration Chapter 7

  31. Answer Key Chapter 7

  32. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  33. Hydrogenation • Reduction - formation of C—H bond. • PtO2 solid catalyst - heterogeneous reaction. • syn chemistry. • “Alkenes are much more reactive than most other functional groups toward catalytic hydrogenation.” - p251 Chapter 7

  34. Hydrogenation Chapter 7

  35. Answer Key Chapter 7

  36. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  37. Hydroxylation • Forming 1,2-dialcohol or diol (glycol). • Forming cyclic osmate intermediate therefore syn stereochemistry. Chapter 7

  38. Hydroxylation Chapter 7

  39. Answer Key Chapter 7

  40. Breaking up 1,2-diol Chapter 7

  41. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  42. Alkene + Carbene Chapter 7

  43. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  44. Simmons-Smith Reaction Chapter 7

  45. Alkene + Carbene p 248 “…stereospecific … Starting from a cis alkene … only cis disubstituted cyclopropane is produced; starting from a trans alkene, only trans-disubstituted cyclopropane is produced.” Chapter 7

  46. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

  47. Oxidation • Reducing the length of the carbon skeleton. • Alkene  aldehyde and/or ketone. • Oxidizing agents are ozone or potassium permanganate. Chapter 7

  48. Alkene + Ozone Chapter 7

  49. Answer Key Chapter 7

  50. HX ether X2 CH2Cl2 KMnO4, H3O+ X2 O3 H2O(xs) Zn/H3O+ HgAc2, H2O/THF CH2I2 NaBH4 Zn(Cu) ether BH3, THF CHCl3 H2O2, OH- KOH H2 OsO4 NaHSO4, H2O Pd or Pt M halogenation anti halohydrination oxidation M anti oxymercuration M oxidation Alkene hydroboration non-M syn Simmons-Smith syn hydrogenation syn carbenation syn syn hydroxylation Chapter 7

More Related