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Haloform Reaction

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    40429

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    The haloform reaction is the reaction of a methyl ketone with chlorine, bromine, or iodine in the presence of hydroxide ions to give a carboxylate ion and a haloform. There is one aldehyde that undergoes the haloform reaction, which is acetaldehyde.

    eg:

    haloformreaction1.png

    mechanism:

    haloformreaction2.png

    When the halogen used is iodine, the haloform reaction can be used to identify methyl ketones because iodoform is a yellow solid with a characteristic odor. The test is known as the iodoform test. Alcohols that have the general structural formula 1 also give a positive iodoform test because, under the reaction conditions, they are oxidized (see oxidation) to the corresponding methyl ketone, or, in the case of ethanol to acetaldehyde, which is the only aldehyde that undergoes haloform reaction.

    haloformreaction3.png

    R = H, alkyl, aryl

    This page titled Haloform Reaction is shared under a All Rights Reserved (used with permission) license and was authored, remixed, and/or curated by Gamini Gunawardena via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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