Question

Following are structural formulas for two enamines. (a) (b) Draw structural formulas for the secondary amine and carbonyl compound from which each enamine is derived.

Short answer

Answer: For Enamine 1, the structures are secondary amine 1 (N-ethyl propylamine) and carbonyl compound 1 (acetone). For Enamine 2, the structures are secondary amine 2 (N-methyl ethylamine) and carbonyl compound 2 (propanal).

Step-by-step solution

Understand Enamines and Enamine Formation

Enamines are organic compounds formed by the reaction between a secondary amine and a carbonyl compound. They contain an alkene group (C=C) and an amine functionality, combined in the same molecule. The most common enamine formation is the reaction of a secondary amine with an aldehyde or ketone.

Recognize the Enamine Structures

First, let's identify the enamine structures given: Enamine 1:  Enamine 2: 

Derive the Secondary Amine and Carbonyl Compound for Enamine 1

To derive the secondary amine and carbonyl compound for Enamine 1, remove one hydrogen from the nitrogen atom and break the double bond between the carbons adjacent to nitrogen, creating a carbonyl compound. Add a hydrogen to the carbon, so it's now a carbonyl group: Secondary Amine 1:  Carbonyl Compound 1 (Ketone): 

Derive the Secondary Amine and Carbonyl Compound for Enamine 2

To derive the secondary amine and carbonyl compound for Enamine 2, remove one hydrogen from the nitrogen atom and break the double bond between the carbons adjacent to nitrogen, creating a carbonyl compound. Add a hydrogen to the carbon, so it's now a carbonyl group: Secondary Amine 2:  Carbonyl Compound 2 (Aldehyde):