Question

Which of the following(s) compounds can show tautomerism?

• A.

  

• B.

  

• C.

  

• D.

  

Answer 1

The correct option is D

1. Tautomerism is functional isomerism in which two isomers quickly interconvert to one other and both forms should be in dynamic equilibrium with one another.
2. The relocation of the hydrogen atom occurs as a result of this reaction, then these two structural isomers are referred to as tautomers.

The two requirements for tautomerism are now:

• Compounds must have an electron-withdrawing atom or group, i.e., an atom that is more electronegative than carbon.
• That electron-withdrawing atom must be coupled to carbon, and that carbon must be linked to another carbon-containing $\alpha$ hydrogen atom.

The explanation for correct answers:

Options B and D:

Option B:

This compound can show tautomerism because in tautomerism no change in the number of sigma and pi-bonds takes place, which is possible in only the below compound.

Option D:

Keto-enol tautomerism is possible only in that aldehyde and ketone have at least one $\alpha$ hydrogen atom that can convert the carbonyl group to the enolic group.

Therefore, the correct option is B and D.