Question

Which among the following show tautomerism?
(A)Alcohols
(B)Phenols
(C)Ethers
(D)Anisole

Answer 1

Hint :The phenomenon in which a single chemical compound tends to exist in two or more interconvertible structures that are different in terms of the relative position of one atomic nucleus which is generally the hydrogen atom is called tautomerism.

Complete Step By Step Answer:
Tautomers are the isomers of a molecule that exist in a solution. They are interchangeable forms as the chemical bonds are rearranged many times. This is different from chirality. To exhibit tautomerism, the carbonyl group should have an alpha hydrogen which is attached to the $ s{p^3} $ hybridized carbon atom. There is an exchange of a hydrogen atom between two other atoms while forming a covalent bond to either one in tautomerism. It is a reversible process. To exhibit tautomerism, either acid or base can catalyse the proton transfer. In the first step of acid-catalyzed tautomerization of keto form, hydronium ion protonated carbonyl oxygen atom and then, water removes alpha-hydrogen atom to give the enol. Tautomerism is a type of functional isomerism in which both isomers are in dynamic equilibrium with each other. In phenol, the alpha carbon atom contains hydrogen attached to it. So, it exhibits keto-enol tautomerism as there is a presence of alpha hydrogen atoms.
Therefore, option B is the correct answer.

Note :
Keto-enol tautomerism refers to a chemical equilibrium between the keto form and the enol form of a compound. The keto form of the compound is thermodynamically more stable and is highly favoured.