Retro-Aldol Reaction: Bond Breakage in Carbonyls

The retro-aldol reaction breaks a carbon–carbon bond in an aldol product. It is the reverse of aldol addition. Under acidic or basic conditions, this cleavage produces two carbonyl compounds.

The mechanism follows three steps. First, a base removes the proton from the hydroxyl group of a β-hydrox...

Recall that the aldol addition reaction is unfavorable for ketones under basic conditions.

The retro-aldol reaction is the exact reverse of the aldol addition, where the β-hydroxy ketone in the presence of an aqueous base is preferably cleaved into two ketone molecules as the retro-aldol products.

The reaction mechanism consists of...