Chapter 22: Enols and Enolates
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alpha protons
• protons on carbons directly attached to carbonyl carbon • alpha protons are acidic • removal of alpha proton generates an anion that is fairly reactive
Compounds that differ by the placement of just one proton are called ___.
• tautomers
In Keto-Enol tautomerization, equilibrium favors the ____ form
• ketone form, becuase carbonyl formation is driving force
Ketones can be converted to Enols and vice-versa via which methods?
• acid or base catalyzed methods
Acid catalyzed keto-enol tautomerization
• protonate with H3O+ • deprotonate with H2O • enolate intermediate
Base-catalyzed keto-enol tautomerization
• protonate with H2O • deprotonate with -OH • enolate interediate
Enols as nucleophiles
• only occurs with ketones that are able to tautomerize to enol
Forming alpha-halo ketones
Forming alpha-halo ketones:
Hell-Volhard-Zelinsky Reaction:
-used to halogenate COOHs
Making enolates:
Alkylation of Enolates
Alylation of assymetrical enolates: This is the ____ product
• Thermodynamic product
Alkylation of assymetrical enolates: this is the ____ product
• kinetic
Aldol addition:
Aldol condensation:
• creates alpha-beta unsaturated ketones
If using two ketones in aldol addition, you need to make sure that one ketone has no ____, to prevent crossed-aldol reactions
alpha protons
Claisen Condensation
• When ester enolates attack esters • note: the alkoxide used much match the ester
Decarboxylation
Acetoacetic Ester Synthesis
• makes ketones
Malonic Ester Synthesis
