What is the most likely product of the following reaction Cl

What is the most likely product of the following reaction? Cl HOAc 0 CI CiI OA mixture of I and I

Solution

Answer:

A mixture I and II are most likely to form in the given reaction.

The given reaction is an acid catalysed -halogenation of ketones.

Since the given ketone is an unsymmetrical ketone, hence there is a possibility for the formation of I and II.

This reaction proceeds through ‘enol’ mechanism. Hence, the formation of the products completely depends on the rate of formation of the ‘enol’ intermediate.

The formation of enol is rate determining step in this reaction.

The reactivity order of acid catalysed halogenation of unsymmetrical ketones is R₂CH(C=O)R\' > RCH₂(C=O)R\' > CH₃(C=O)R\'. However, irrespective of the above given reactivity, the formation of mixture of regio-isomers (-halogenated products) is more prominent.