Question
Define metamerism and tautomerism.
Solution
Metamerism: Compounds having the same molecular formula but a different number of carbon atoms (or alkyl groups) on either side of the functional group (i.e.– O –, – S – CO – NH–) are called metamers and the phenomenon is called metamerism. For example, ethoxyethane and 1-methoxy propane represent a pair of metamers.
Pentan-2-one and pentan-3-one represent a pair of metamers.
Tautomerism: It arises due to 1, 3-migration of a hydrogen atom from one polyvalent atom to the other within the same molecule. Isomers thus obtained which exist in dynamic equilibrium with each other are called tautomers and the phenomenon is called tautomerism.
Out of several types of tautomerism, keto-enol tautomerism is the most important. In this isomerism, the tautomers differ from each other in the point of attachment of a hydrogen. For example, propanone exists as a tautomeric mixture of two forms, the keto form and the enol form, which differ in the point of attachment of a hydrogen.
Pentan-2-one and pentan-3-one represent a pair of metamers.
Tautomerism: It arises due to 1, 3-migration of a hydrogen atom from one polyvalent atom to the other within the same molecule. Isomers thus obtained which exist in dynamic equilibrium with each other are called tautomers and the phenomenon is called tautomerism.
Out of several types of tautomerism, keto-enol tautomerism is the most important. In this isomerism, the tautomers differ from each other in the point of attachment of a hydrogen. For example, propanone exists as a tautomeric mixture of two forms, the keto form and the enol form, which differ in the point of attachment of a hydrogen.
