Isomerism

Isomerism

Contents

• Isomerism

• Structural isomerism

• Chain isomerism

• Positional isomerism

• Functional isomerism

• Metamerism

• Tautomerism

• Stereo isomerism

• Geometrical isomerism

• Optical isomerism

Learning
Objectives

At the end of this lecture, student will be able to

• Define the term isomerism

• Differentiate between the different types of isomerism
with examples

Isomerism

Definition

• Two or more compounds with same molecular formula but
different physical or chemical properties

• Isomers

Types of isomerism

• Structural isomerism

• Stereo isomerism

Structural isomerism

• Two or more compounds with same molecular formula and
different structural formula

Stereo isomerism

• Two or more compounds with same structural formula and
different configuration

TYPES OF ISOMERISM

Chain Isomerism

• Difference in the nature of the carbon chain

• Examples

Position isomerism

• Position of the substituent atom or group or unsaturated
linkage

• Examples

Functional isomerism

• Difference in the nature of the functional group

• Examples

Metamerism

• Nature of the alkyl groups attached to the same functional
group

• Example

CH3—CH2—NH—CH2—CH3         
CH3—CH2—CH2—NH—CH3

Keto enol tautomerism

– Tautomers

– Keto tautomer – more stable

Keto enol tautomerism

• Examples

Geometrical isomerism

• Geometrical isomers

• Cis isomers

• Trans isomers

Optical isomerism

• Laevo isomer

• Dextro isomer

Summary

• Isomerism is the phenomenon in which two or more compounds
have the same molecular formula but different properties

• Structural isomers have same molecular formula but
different structural formula

• Stereo isomers have same molecular formula but atoms
occupy different positions in space

Leave a Comment