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Alcohols

Alcohols. Biological Activity Nomenclature Preparation Reactions. Some Alcohols. Alcohols are Found in Many Natural Products. Paralytic Shellfish Poisoning. Ethanol: the Beverage. Methanol: Not a Beverage. Oxidation levels of oxygen- halogen- and nitrogen- containing molecules.

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Alcohols

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  1. Alcohols Biological Activity Nomenclature Preparation Reactions

  2. Some Alcohols

  3. Alcohols are Found in Many Natural Products

  4. Paralytic Shellfish Poisoning

  5. Ethanol: the Beverage

  6. Methanol: Not a Beverage

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

  8. Acidity of Alcohols • Due to the electronegativity of the O atoms, alcohols are slightly acidic (pKa 16-18). • The anion dervived by the deprotonation of an alcohol is the alkoxide. • Alcohols also react with Na (or K) as water does to give the alkoxide (red-ox):

  9. Withdrawing Groups Enhance Acidity alcohol pKa CH3OH 15.54 CH3CH2OH 16.00 CF3CH2OH 12.43 (CH3)3COH 18.00 (CF3)3COH 5.4

  10. Physical Properties CH3CH2CH3 -42 0.08 i CH3OCH3 -25 1.3 ss CH3CH2OH 78 1.7 vs b.p. oC m D sol. in H2O

  11. Intermolecular H-Bonding

  12. Alcohol Nomenclature

  13. Nomenclature

  14. Preparation of Alcohols • Reduction of ketones and aldehydes • Reduction of esters and carboxylic acids • Hydration of Alkenes • Nucleophilic addition • Grignard reaction • Acetylide addition • Substitution • Epoxide opening

  15. NaBH4 Reduction

  16. Some Examples

  17. Two Alcohol Products Form in Lab

  18. LiAlH4 Reductiona Stronger Reducing Agent

  19. LiAlH4 is a much stronger reducing agent

  20. NaBH4 is More Selective

  21. Oxymercuration HydrationMarkovnikov

  22. Hydroboration HydrationAnti-Markovnikov

  23. Base Catalyzed Ring-Opening of Epoxides

  24. Acid Catalyzed Ring-OpeningAqueous and in Alcohol

  25. RegiochemistryRing Opens at More Hindered Site

  26. Nucleophilic addition to Carbonyl CompoundsAcetylides

  27. Organometallic ChemistryGrignard Reaction

  28. Grignard Reagents React With Ketones to form tertiary alcohols

  29. Grignard Reagents React With Aldehydes to form secondary alcohols

  30. Grignard Reagents React With Formaldehyde to form primary alcohols

  31. Grignard Reagentsreact (twice) withEstersto form3o Alcohols

  32. Grignard Reagents open Epoxides

  33. Ring-Opening is Sterically Controlled

  34. Grignard Summary

  35. Grignard Summary

  36. Grignard Reagents are exceptionally strong bases

  37. Synthesis

  38. Retrosynthetic Analysis

  39. 4-Step Synthesis

  40. Synthesize Using Only 1,2, or 3-Carbon Reagents

  41. Retrosynthesis

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

  43. Alcohols are Synthetically Versatile

  44. Oxidation -Reduction

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

  46. Mechanism

  47. Oxidation of 1o Alcohols

  48. PCC oxidizes 1o Alcohols to Aldehydes

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