Aldol Condensation Theory

what type of reaction is aldol condensation?

• an addition reaction of an enol or enolate to a carbonyl compound such as an aldehyde or ketone

what happens during the aldol condensation?

• The reaction essentially converts two carbonyl compounds into a β-hydroxy carbonyl compound.

• The β-hydroxy carbonyl compound undergoes further dehydration under elevated reaction temperatures to produce an α,β-unsaturated carbonyl compound

where does the enolate come from?

• The enol or enolate employed in the reaction is formed from an aldehyde or ketone that contains an α-proton.

why are we using one carbonyl compound that contains an alpha-proton?

• to avoid the need to preform the enolate as a separate step. 

properties of carbonyls

• polarization of the carbon-oxygen p-bond, owing to the relatively high electronegativity of the oxygen atom.

• increase the acidity of alpha-hydrogen atoms, making them nucleophilic

pKa equation

• pKa = -logKa

the ability of carbonyls to make alpha-hydrogens more acidic comes from…

• due to its inductive effect and its ability to delocalize and thereby stabilize the negative charge in the enolate ion

aldol

• A b-hydroxycarbonyl compound

when is the reaction complete?

• once the reaction is too thick to stir it is complete.