Enolate Anions & Enamines

structure of an enolate

structure of the keto form

structure of the enol form

symmetrical ketone + strong base (⁻OH)

results in the same enolate

ketone w/a single alpha carbon + strong base (⁻OH)

results in an enolate

ketone w/two different alpha carbons + strong base (⁻OH)

results in two different enolates (thermodynamic is more stable, but kinetic forms faster)

thermodynamic enolate

kinetic enolate

aldehyde/ketone + ⁻OH, X₂

(α-halogenation) all α hydrogens are replaced by X

aldehyde/ketone + H⁺, X₂

(α-halogenation) only one α hydrogen is replaced by X, resulting in a chiral center

aldehyde/ketone + ⁻OH, X₂ (xs)

(haloform formation) results in a carboxylate anion and a haloform

enolate + aldehyde/ketone

results in a hydroxyl ketone with α-β orientation

LDA, and KOt-butyl needs __ conditions and forms a __ product

LDA, KOt-butyl needs kinetic conditions (-78°C) and forms a kinetic product

NaOH, KOH, and MeOH needs __ conditions and forms a __ product

NaOH, KOH, and MeOH needs thermodynamic conditions (high temperatures) and forms a thermodynamic product

ester + alkyl oxide

(Claisen condensation) results in an aldol

structure of a Claisen product

carbonyls are carbonyl carbon and β-carbon oriented (a β-keto ester)

structure of Dieckmann product

carbon ring with carbonyls are carbonyl carbon and β-carbon oriented (a β-keto ester carbonyl ring)

base-catalyzed (⁻OH) α-halogenation

all hydrogens on the α-carbon are converted to halogens

acid-catalyzed (⁺H) α-halogenation

a hydrogen on the α-carbon are converted to the halogens, creating a chiral center

carbonyl with a single α-carbon + acid (⁻OH), X (excess)

haloform formation that results in a carboxylate salt and a CH(X)₃

enolate + acid (⁺H), ∆

results in an α-β unsaturated aldehyde/ketone

aldehyde/ketone + LDA

results in the corresponding enolate

No heat is required in a condensation reaction when:

there is a conjugated system present

structure of an aldol product

α-β-unsaturated carbonyl

structure of an aldol condensation product

a β-hydroxyl carbonyl

What's the difference between an enol and an enolate?