lecture 19 - Formation of an Enolate Anion Enolate anions...

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Enolate Enolate Anions Anions Chapter 19 Chapter 19 Formation of an Formation of an Enolate Enolate Anion Anion ± Enolate anions are formed by treating an aldehyde or ketone with base most of the negative charge in an enolate anion is on oxygen CH 3 -C-H O NaOH HC C -H O H O - Na + H H 2 O + + An enolate anion Enolate Anions ± Enolate anions are nucleophiles in S N 2 reactions An enolate anion nucleophilic substitution A 1° haloalkane or sulfonate R R R O + R' Br O R R R S N 2 + Enolate Enolate Anions Anions ± Enolate anions also function as nucleophiles in carbonyl addition reactions An enolate addition A ketone A tetrahedral carbonyl addition intermediate R R R O + O O R R R O Enolate Anions ± Enolate anions react primarily at carbon for two reasons 1) There is always a counterion associated with with the enolate anion. These counterions are more tightly associated with the O than the α -carbon blocking the approaching electrophile 2) Reactions at equilibrium favor stronger bonds. C=O bonds are stronger than C=C bonds See next slide
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The The Aldol Aldol Reaction Reaction ± The most important reaction of enolate anions is
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lecture 19 - Formation of an Enolate Anion Enolate anions...

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