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Alcohols & Thiols & Ethers

Sources Structure, Nomenclature, Properties Acidity and Basicity Rx with active metals Conversion to R-X, inorganic acid halides Rxs with HX S N 1/S N 2, sulfonates Dehydration of alcohols Oxidation of 1 o and 2 o alcohols Oxidation of glycols

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Alcohols & Thiols & Ethers

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  1. Sources Structure, Nomenclature, Properties Acidity and Basicity Rx with active metals Conversion to R-X, inorganic acid halides Rxs with HX SN1/SN2, sulfonates Dehydration of alcohols Oxidation of 1o and 2o alcohols Oxidation of glycols [Pinacol & Thiols/Sulfur chemistry - skip] Chapter 11 Chapter 10 Alcohols & Thiols &Ethers 6, 31, ss34

  2. Chapter 10 synthesis sources nomenclature (alcohol & ethers) properties reactions acid base active metal substitution oxidation

  3. Preparation of alcohols - (review)

  4. Chapter 10 synthesis sources nomenclature (alcohol & ethers) properties reactions acid base active metal substitution oxidation

  5. IUPAC names – alcohol sp3C-OH -longest chain that contains the -OH = root -OH gp lowest number - suffix -e to -ol Nomenclature alcohols & ethers ether R-O-R’ sp3C, sp2C, spC in R & R’ bonded to O -always subsituent - #-prefix, alkoxy (special ethers #,#-epoxy) 1-ethoxy-2-butanol

  6. Epoxides - 11 - special ethers Nomenclature - #,#-epoxy (substituent) oroxirane ether acetylene alcohol #,#-epoxy-#-pentyn-#-ol (4S)-4,5-epoxy-2-pentyn-1-ol

  7. IUPAC names Longest chain that contains the -OH = root Give -OH group lowest number Change suffix -e to -ol (S)-2-methyl-1-butanol Nomenclature-Alcohols

  8. H C 3 oxygen sp3 Structure - Alcohols • Alcohol functional group: • -OHgroup bonded to an sp3 hybridized carbon • bond angles ~ 109.5° H H H C O

  9. etc. R H R H O O O H R R H O Physical Properties Hydrogen bonding: H bonded to an electronegative atom (F, O, or N) Hydrogen bond weak (~ 5 kcal/mol)

  10. ethanol & dimethyl ether - constitutional isomers but weak hydrogen bonds have dramatic effects: Physical Properties hydrogen bonds no hydrogen bonds

  11. Reactions alcohols: acid base indirect substitution indirect-elimination active metals oxidation ethers: base indirect substitution indirect-elimination epoxides: substitution, indirect& direct

  12. weak acids Acidity of Alcohols conjugate basesstrong

  13. 8.5 RSH Acidity of Alcohols

  14. Acidity of Alcohols Acidity  on: stabilization and solvation electron donation destabilize alkoxides Steric BULK decreases solvation

  15. Alcohols + Li, Na, K (active metals) form metalalkoxides alcohols rx with metals metal alkoxide sodium methoxide

  16. rx with metals sodium cyclohexoxide

  17. basicity of alcohols/ethers weak Lewis base (water-like) oxonium ion R = H or alkyl

  18. Alcohols/Ethers indirect Substitution (with HX) 3° alcohols (ethers) react very rapidly with HCl, HBr, HI. 1°alcohols/ethers are unreactive under these conditions R = H or alkyl

  19. 2° alcohols + HBr (or HI ) indirect Substitution (with HX) racemization, rearrangement, olefins

  20. -H+ +X- +X- [-HOR] good leaving group 2o or 3o ROH/ROR’ with HX - SN1 racemization, rearrangement, olefins R = H or alkyl

  21. X(-) displace 1o ROH/ROR’with HI or HBr - SN2 R’ = H or alkyl

  22. indirect Substitution (with SOCl2)

  23. 2nd ROH to RBr 3rd ROH to RBr indirect Substitution (with PBr3)

  24. indirect Substitution R= H, alkyl R’= H, alkyl; X= Br, I

  25. alcohols - alkyl sulfonates, good Lgp

  26. S S DMF R S alkyl sulfonates (sulfonate ester) good leaving group for Sn2 rx

  27. rx: alkyl sulfonates prep:

  28. rx: alkyl sulfonates prep:

  29. 2° alcohols (ethers) 3° alcohols (ethers) dehydration of ROH/[-HOR’] of ROR’ 1° alcohols (ethers) with H2SO4 or H3PO4 R = H or alkyl

  30. Mechanism - same forward or reverse. alkene addition and -elimination compete Dehydration ofROH (-OR of ethers)

  31. Chapter 10 synthesis sources nomenclature properties reactions acid base active metal substitution oxidation

  32. Oxidation

  33. Pyridinium chlorochromate (PCC): pyridine + CrO3 [Cr(VI)] + HCl Oxidation: 1° ROH PCC converts 1° alcohols to aldehydes and 2o alcohols to ketones

  34. Oxidation aldehyde acid ketone NR (no reaction)

  35. + -elimination of H and chromate

  36. Oxidation: 1° ROH hydrate hydrate

  37. K2Cr2O7 and many other reagents Oxidation 1o and 2o ROH

  38. Oxidation of Glycols with H5IO6 (or HIO4•2H2O) acyclic or cis-1,2 cyclic diols

  39. Oxidation of Glycols with H5IO6 (or HIO4•2H2O) 11

  40. How does one make butanal from 1-bromobutane?

  41. What else can be made using the chemistry of chapters 3, 6, 7, 8, 9, 10, 11 & “15”?

  42. future chapter chemistry Chapter 15

  43. Chapter 10 Chapter 11/15 synthesis synthesis sources nomenclature properties reactions acid base active metal substitution oxidation

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