Question

What statement is correct for Keto-Enol Tautomerism?
A.Tautomerism is catalysed by acid and base.
B.Tautomers are present in a dynamic equilibrium state
C.Generally keto form is more stable than the enol form ketones
D.Atomic arrangements are the same in tautomerism.

Answer 1

In organic molecules, there exists an equilibrium between the ketone form and the enol form of the molecules which is called “keto-enol” tautomerism. This equilibrium is dynamic in nature and the dominant structure is dependent on different conditions.

Complete answer:
We shall analyse each option and relate them to the formation of keto-enol tautomers.
The mechanism is acid/base catalysed as it acts as the catalyst responsible for this isomeric change, i.e. addition of hydrogen ions by acid or deprotonation by base.
The formation of a tautomeric form is dependent upon the pH and the temperature of the medium and the tautomers are present in a dynamic equilibrium that and any change in the surrounding conditions can shift the equilibrium.
In most of the keto-enol tautomeric cases the equilibrium is shifted more towards the keto form indicating that it is the more stable form.
The arrangement of the atoms are different in tautomers because they are isomers, which means they have the same chemical formula but different arrangement of atoms.

So, among all the statements, A, B, and C are correct.

Note:
The “keto-enol” tautomerism is an acid/base catalysed mechanism where the carbonyl form is initially protonated and thereby the conjugate base formed extracts proton from one of the alkyl carbon atoms while the shared electron share between the hydrogen atom and the carbon atom forms the double bond forming the enol.