7b Flashcards
what is enolisation
forming an enol from a carbonyl group
ketone to enol mechanism name
tautomerisation
intramolecular transfer of a proton
describe an enol
OH bonded to a C=C
acid catalysed enolisation // enol formation from a carbonyl group
O is protonated using pTsOH
water removes a H with then forms a double bond and neutralises the OH to form an enol
this can be reversed buy the lone pair on O resonating C=C attacking a H to form a carbonyl again
base catalysed enolisation// enol formation
EtO- attacks H and leaves a carbanion
resonance occurs,, forms a double bond with an O-
enolate is formed
describe an enolate
deprotonated enol.
enol is OH and C=C
enolate is O- and C=C
resonance stabilised,, also O is electronegative and so stabilises the - charge
when is an enolate formed
when base catalysed enolisation occurs
when an alpha H on a carbonyl group is removed, forms a carbanion, which then resonance occurs with.
what is an aldol
a moelcule where an OH is a couple of carbons away from an aldehyde // ketone
the OH is on the beta carbon
what is an enolate
O- bonded to C=C
a bronsed lowry base - accept H
a lewis base ( donate e- ,, nucleophiles,, attack C in carbonyls)
how is an aldol formed,, OH / O- couple Cs away from an aldehyde // ketone
aldehyde,, use OEt to deprotonate an alpha H
forms a carbanion,, to form a nucleophile.
react the Ch2- with another aldehyde,, - chargw attacks C on carbonyl,, e- move up to the O,, O- is protonated using EtOH
base removes the middle H to form another double bond (kinda gives anhydride vibes)
acid catalysis // aldol condensation
aldehyde is protonated using pTsOH
alpha H is used to form a double bond
double bond attacks another aldehyde
OH is protonated,, middle H is removed by base to form a double bond and kick off h20
aldol condensation reaction product
double bond on beta carbon then c=o
aldol addition product
OH on beta carbon then c=o
