Haloform reaction

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The haloform reaction is the chemical reaction where a haloform (CHX3, where X = halogen) is produced by the exhaustive halogenation of a ketone with one methyl group (R–CO–CH3, where R = H, alkyl or aryl) in the presence of a base.


The halogen is dissolved in a basic solution, such as NaOH. The solution is then cooled, as the reaction is very exothermic. Ketones such as acetone, methyl ethyl ketone, 2-pentanone can be used in the reaction, but secondary alcohols such as isopropanol can also be used.

The only primary alcohol and aldehyde to undergo this reaction are ethanol and acetaldehyde.


The reaction can be used to produce chloroform (CHCl3), bromoform (CHBr3), or iodoform (CHI3). Fluoroform (CHF3) cannot be produced via this route as the hypofluorite ion is too unstable to work.

Can also be used to detect ketones in an organic sample, iodoform test being the most convenient.


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