Question

Question: Draw the enol form of each keto tautomer in parts (a) and (b), and the keto form of each enol tautomer in parts (c) and (d).

a.

b.

c.

d.

Short answer

Answer

a.

b.

c.

d.

Step-by-step solution

Step-by-Step SolutionStep 1: Tautomers

Isomers that differ only in the position of protons and electrons are called tautomers.The carbonyl group with alpha hydrogen show keto-enol tautomerism.

Interconversion of keto and enol form

Keto-enol tautomers are structural isomers.In enol form, OH is attached to a double bond. In keto form, the proton from OH is deprotonated, and the carbonyl group is formed.

Conversion of structures

a. Carbonyl group is protonated, and OH is attached to C=C, as shown below

Enol form of the tautomer

b. The Carbonyl group is protonated, and OH is attached to C=C, as shown below. There are two possible structures.

Two possible enol forms of the tautomer

c. OH is deprotonated, and the C=O group is formed, as shown below

Keto form of the tautomer

d. OH is deprotonated, and the C=O group is formed, as shown below

Keto form of the tautomer