Chapter 22.SE, Problem 61AP

Interpretation Introduction

Interpretation:

The observation, Grignard reaction of cyclohexanone with tert-butylmagnesium bromide yields only about 1% of the expected addition product along with 99% unreacted cyclohexanone. If D₃O⁺ is added to the reaction mixture after a suitable period, however, the unreacted cyclohexanone is found to have one deuterium atom incorporated into it, is to be explained.

Concept introduction:

Grignard reagents add to the carbonyl group in aldehydes and ketones. The addition product when hydrolyzed with aqueous acids yields a secondary alcohol in the case of aldehydes other than formaldehyde and a secondary alcohol in the case of ketones.

Ketones exist in acid catalyzed reversible equilibrium with their enol tatomers.

To explain:

The observation, Grignard reaction of cyclohexanone with tert-butylmagnesium bromide yields only about 1% of the expected addition product along with 99% unreacted cyclohexanone. If D₃O⁺ is added to the reaction mixture after a suitable period, however, the unreacted cyclohexanone is found to have one deuterium atom incorporated into it.