Chapter 22 November 16

Chapter 22 November 16 - General Reaction: Mechanism: 4...

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1 Base Catalysis of Enolization Mechanism: Bronsted­Lowrey bases catalyze keto­enol tautomerization by abstracting an α ­hydrogen and forming a reactive enolate intermediate α ­Hydrogens are weakly acidic
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2 General Reactivity of Enols Enols act as nucleophiles and react with electrophiles to produce addition products Enols, like alkenes, are e ­ rich. Enols, however, have a higher e ­ density than alkenes and are therefore more reactive The high e ­ density comes from electrons donated by the oxygen
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3 Alpha Halogenation of Aldehydes and Ketones
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Unformatted text preview: General Reaction: Mechanism: 4 Evidence of the RateLimiting Enol Formation Mechanism 5 Elimination Reactions of AlphaBromoketones Examples: 6 Alpha Bromination of Carboxylic Acids HellVolhardZelinskii Reaction: Example: General Reaction Scheme: 7 Why is an alpha hydrogen acidic? Resonance Examples: . 8 Reagents Used for Enolate Formation LDA (Lithium Diisopropylamide): Ketones are weaker acids than alcohol, therefore a stronger base than an alkoxide is needed to form an enolate...
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Chapter 22 November 16 - General Reaction: Mechanism: 4...

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