Alpha Halogenation

The process of acid catalyzed keto-enol tautomerism allows aldehydes and ketones with α-hydrogens to react with electrophiles. α-halogenation is a typical reaction of this type. In this reaction, the π electrons between the vinylic carbons of an enol form of the aldehyde or ketone are subject to electrophilic attack, leading to a new bond between the α?carbon and halogen.