lecture 19.1

lecture 19.1 - 19-19-1Organic Organic H BrownWilliam H...

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Unformatted text preview: 19-19-1Organic Organic ChemistryChemistryWilliam H. BrownWilliam H. BrownChristopher S. FooteChristopher S. FooteBrent L. IversonBrent L. Iverson19-19-2Enolate AnionsEnolate AnionsChapter 19Chapter 1919-19-3Formation of an Enolate AnionFormation of an Enolate Anion◆Enolate anions are formed by treating an aldehyde or ketone with base•most of the negative charge in an enolate anion is on oxygenCH3-C-HONaOHH CC-HOHH CC-HO -Na+HH2O++An enolate anion19-19-4Enolate AnionsEnolate Anions◆Enolate anions are nucleophiles in SN2 reactions and carbonyl addition reactionsAn enolateanionnucleophilicsubstitutionA 1 haloalkaneor sulfonateRRRO+R'BrORRRSN2R'+BrAn enolateanionnucleophilic additionA ketoneA tetrahedral carbonyl addition intermediateRRRO+R'R'OORRROR'R'19-19-5The Aldol ReactionThe Aldol Reaction◆The most important reaction of enolate anions is nucleophilic addition to the carbonyl group of another molecule of the same or different compound•although these reactions may be catalyzed by either acid or base, base catalysis is more common19-19-6The Aldol ReactionThe Aldol Reaction◆The product of an aldol reaction is•a β-hydroxyaldehyde•or a β-hydroxyketoneCH3-C-HOCH2-C-HHONaOHβΧΗ3-ΧΗ-ΧΗ2-Χ-ΗΟΗΟα+AcetaldehydeAcetaldehyde3-Hydroxybutanal(a b-hydroxyaldehyde; racemic)OCH3-C-CH3CH3-C-CH3OCH2-C-CH3OHBa(OH)2Ba(OH)2βαΟΗΧΗ3ΧΗ3-Χ-ΧΗ2-Χ-ΧΗ3ΧΗ3ΧΗ3-Χ-ΧΗ2-Χ-ΧΗ3ΟAcetone+4-Hydroxy-4-methyl-2-pentanone(a b-hydroxyketone)+Acetone19-...
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lecture 19.1 - 19-19-1Organic Organic H BrownWilliam H...

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