MolSynapsequestion bank

MolSynapse / Question bank / Aldehydes, Ketones and Carboxylic Acids / Haloform reaction

JEE Main levelOne or more correct optionsDifficulty 2 of 3co128

Which statements about the mechanism of the haloform reaction of a methyl ketone $RCOCH X_{3}$ in aqueous $NaOH$ and $I X_{2}$ are correct?

AThe first step is removal of an alpha hydrogen by hydroxide to give an enolate
BSuccessive halogenations become faster because halogen atoms increase the acidity of the remaining alpha hydrogens
CThe $CI X_{3} X^{-}$ group is expelled from a tetrahedral intermediate formed by attack of $OH X^{-}$ on the carbonyl carbon
DThe group R is lost as a carbanion and $CI X_{3}$ stays on the acid

Answer: A, B, C

Enolate formation, rapid repeated halogenation (due to the

- I

effect of halogen) and expulsion of

CI X_{3} X^{-}

from the tetrahedral intermediate are the three correct steps. It is

CI X_{3} X^{-}

, not R, that leaves, and the acyl part with R stays as the carboxylate.

Practice Aldehydes, Ketones and Carboxylic Acids More on Haloform reaction

Previous questionNext question

More questions on Haloform reaction