Chapter 7 : Aldehydes and Ketones II Flashcards
what is the alpha carbon
carbon adjacent to the carbonyl carbon
what are alpha hydrogens
hydrogens attached to the alpha carbon
what is the acidity of alpha hydrogens
relatively acidic ; can be removed with a STRONG base
what is an enolate
de-protonation of alpha hydrogen results in negative charge on alpha carbon
how is an enolate stabilized
enolates can be stabilized through resonance with carbonyl carbon
what is the reactivity of ketones
less reactive with nucleophiles due to steric hinderance; enolate is less stable due to electron donating alkyl groups
what are tautomers
isomers that can be interconverted by moving a hydrogen and double bond ; aldehyde <-> enol <–> enolate
enol –> enolate
deprotonation
difference between enol and enolate
enol –> acidic
enolate –> basic ; negative charge ; good nucleophile
what is a Michael addition
enolate attacks an alpha, beta unsaturated carbonyl creating a bond
what are enamines
tautomers of imines ; less common than imines
what is an adol condensation
1) formation of enolate via de-protonation of alpha hydrogen
2) enolate attacks aldehyde/ketone
3) condensation reaction for molecule to come together
4) dehydration reaction to form an alpha, beta unsaturated carbonyl losing -OH + H+ as H2O
what is an aldol
contain both alcohol and aldehyde functional groups
what is a retro-aldol reaction
reverse aldol reactions ;
catalyzed by heat and a base ;
bond between alpha, beta is cleaved
