Question

Write a short note on functional group isomerism.

Answer 1

Isomerism is the phenomenon in which the chemical formula of the compounds is the same but the structural formula is different. Isomerism is divided into two categories; Structural isomerism and stereoisomerism.

(a) Structural isomers are of six types:

1. Chain isomers

2. Positional isomers

3. Functional isomers

4. Metamerism isomers

5. Tautomerism isomers

6. Ring-chain isomers

(b) Stereoisomerism. is divided into two types:

1. Geometrical isomers

2. Optical isomers

The compound that has the same chemical formula but a different functional group present in the compound is called functional group isomerism.

Example: The functional group isomers of the compound with the molecular formula ${\mathrm{C}}_3{\mathrm{H}}_6\mathrm{O}$ is Propanal (${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{CHO}$) and Propanone (${\mathrm{CH}}_3{\mathrm{COCH}}_3$).

In propanal , the functional group is aldehyde and in Propanone, the functional group is ketone present.