Chapter 18.11, Problem 17P

Interpretation Introduction

Interpretation:

The structures of the hemiaminal intermediate and the enamine products formed in the given reactions are to be determined.

Concept introduction:

Aldehydes and ketones contain carbonyl functional group in their parent chain. They are polar molecules due to the presence of an electronegative oxygen atom that tends to attract the electrons in the double bond closer to itself as compared to the carbon atom.

The oxygen acquires a partial negative charge and creates a partial positive charge on carbon atom. Aldehydes and ketones easily undergo nucleophilic addition reactions in which the nucleophile attacks at the carbonyl carbon atom.

When aldehydes or ketones react with a secondary amine, formation of enamine takes place. The nitrogen analog of an enol is known as enamine. The nucleophilic addition reaction of the secondary amine to the carbonyl carbon atom results in the formation of hemiaminal intermediate which further on dehydration forms the enamine product.