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Reactions of Alcohols

Reactions of Alcohols. Oxidation R-X, Ether, and Ester Preparation Protection of Alcohols Synthesis The Logic of Mechanisms. Alcohols are Synthetically Versatile. Oxidation levels of oxygen- halogen- and nitrogen- containing molecules. Oxidation - Reduction.

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Reactions of Alcohols

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  1. Reactions of Alcohols Oxidation R-X, Ether, and Ester Preparation Protection of Alcohols Synthesis The Logic of Mechanisms

  2. Alcohols are Synthetically Versatile

  3. Oxidation levels of oxygen- halogen- and nitrogen-containing molecules

  4. Oxidation -Reduction

  5. Oxidation of 2o Alcohols with Cr(VI)

  6. Mechanism

  7. Oxidation of 1o Alcohols

  8. PCC oxidizes 1o Alcohols to Aldehydes

  9. Oxidation of 1o Alcohols to Aldehydes: PCC

  10. Swern Oxidation

  11. Oxidation Summary

  12. Reduction Summary

  13. Conversion of Alcohol into a Leaving Group • Form Tosylate (p-TsCl, pyridine) • Use strong acid (H3O+) • Convert to Alkyl Halide (HX, SOCl2, PBr3)

  14. Formation of p-Toluenesulfonate Esters

  15. Best to use p-TsClwith pyridine

  16. Reactions of Tosylates:Reduction, Substitution, Elimination

  17. Alcohols to Alkyl Halides

  18. SN1: Carbocations can Rearrange

  19. Lucas Test

  20. Qualitative test for Alcohol Characterization

  21. Other Simple Qualitative Tests

  22. 1o and 2o Alcohols: best to use SOCl2, PBr3,or P/I2

  23. Thionyl chloride mechanism in Pyridine –SN2, Inversion

  24. Thionyl chloride mechanism in Dioxane –2 SN2,Retention

  25. Dehydration of Alcohols – E1

  26. Methide Shift is Faster than Loss of H+

  27. Dimerization of Alcohols:Symmetrical Ethers

  28. Mechanism

  29. Williamson Ether SynthesisPreparation of Unsymmetrical Ethers

  30. Mechanism, SN2

  31. Protection of Alcohols

  32. Alcohol is acidic enough to react preferentially.

  33. Chlorotrimethylsilane (TMS-Cl)

  34. Mechanism is SN2

  35. Protect as trimethylsilyl ether

  36. Give the Reagents…

  37. No Protection needed

  38. Synthesize using cyclohexane, 2-butanol and methanol

  39. Determine Where New Bonds are Formed

  40. Synthesis problem 11-57 (Wade)

  41. Retrosynthesis to alcohols

  42. Retrosynthetic Analysis

  43. Work back to 3 Alcohols

  44. Synthesis

  45. Provide a sequence of steps

  46. Mechanisms Thinking Logically • Do not use reagents that are not given. • Is the product a result of a rearrangement? Only intermediates can rearrange. • Is one of the reagents H3O+? If so, use it in the 1st step. Do not create negatively charged species in acid.

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