Haloform reaction

The haloform reaction cleaves a methyl ketone with halogen and base, producing a haloform and a carboxylate salt.

Enolate: An anion formed by removing an alpha hydrogen from a carbonyl compound, with charge delocalized onto oxygen. Base converts the methyl ketone into an enolate before each halogenation.
Methyl ketone: A ketone whose carbonyl carbon is bonded to a methyl group. Its methyl group supplies the three hydrogens replaced before cleavage.
Iodoform test: A qualitative chemical test that produces yellow iodoform from compounds containing, or oxidizable to, a methyl ketone. The test detects eligible methyl ketones through the haloform cleavage.
Hell–Volhard–Zelinsky reaction: A reaction that alpha-halogenates carboxylic acids using phosphorus halides and molecular halogen. It halogenates alpha carbons but does not cleave methyl ketones into haloform.
Alpha halogenation: Replacement of a hydrogen on a carbon adjacent to a carbonyl group by a halogen. Repeated alpha halogenation transforms the methyl group into a trihalomethyl group.
Hypohalite: An ion containing oxygen and a halogen, such as hypochlorite or hypobromite. Hypohalite species provide the reactive halogen in common reaction conditions.
Acetone: The simplest ketone, with formula (CH₃)₂CO. Acetone undergoes the reaction to give acetate and a haloform.
Favorskii rearrangement: A base-induced rearrangement of alpha-haloketones that produces carboxylic acid derivatives. Both involve basic ketone chemistry, but this reaction rearranges rather than releases haloform.
Nucleophilic acyl substitution: A reaction in which a nucleophile replaces a leaving group attached to an acyl carbon. Hydroxide attacks the carbonyl, enabling cleavage of the trihalomethyl group.
Sodium hypochlorite: The sodium salt of hypochlorous acid, commonly used as aqueous bleach. Bleach supplies chlorine and base for a practical haloform reaction.

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BromoformRelated: Its bromine variant can produce bromoform from suitable methyl ketones.