Aldol

In organic chemistry, an aldol is a structure consisting of a hydroxy group (-OH) two carbons away from either an aldehyde or a ketone.

The name combines the suffix 'ol' from the alcohol and the prefix depending on the carbonyl group, either 'ald' for an aldehyde, or 'ket' for a ketone, in which case it referred to as a 'ketol'.

[1][2] Aldols are the product of a carbon-carbon bond-formation reaction, giving them wide applicability as a precursor for a variety of other compounds.

[1] These reactions may also be done intramolecularly to form 5 or 6 member rings or for stereoselective syntheses in the active area of asymmetric synthesis.

Aldols may also undergo a condensation reaction in which the hydroxy group is replaced by a pi bond.

General aldol structure showing the α and 𝛽 positions of carbons relative to the carbonyl. When R" is -H, it is an aldol, when R" is a carbon, it is a ketol.
Possible stereochemical configurations for chiral aldols. R/S configurations of chiral centers : A: OH is 4R, R-group is 3R B: OH is 4S, R-group is 3S C: OH is 4R, R-group is 3S D: OH is 4S, R-group is 3R