HISTORY:
During early days of development of organic chemistry, the
chemists frequently encountered two or more compounds that had same molecular
formula yet different physical/chemical properties.
It was later realize that the difference in their properties
of compound was due to their difference in their structure.
Isomerism:
Such
compounds which posses the same molecular formula but different structures are
known as isomers and this phenomenon is known as isomerism.
1= Constitutional
Isomerism
2= Stereoisomerism
- Chain
Isomerism
- Position
Isomerism
- Functional
Isomerism
- Metamerism
Isomerism
- Tautomerism
Constitutional
Isomerism or structural isomers is shown by the compounds that have the
same molecular formula but different connectivity.
i.e sequence in which the atoms are bonded to each other in
a molecule.
Chain Isomerism:
Those with Same molecular formula but differ in order in which the carbons are bonded to other is called chain isomers and this phenomena is known as Chain isomerism.
Position
Isomerism:
Same molecular
formula but differ in the position of functional group is said to be position isomers and this phenomenon is called position isomerism
Functional Isomerism:
Same molecular formula but different functional group.
CH3CH2OH
CH3-O-CH3
Ethylalcohol
Dimethyl Ether
Metamerism:
Unequal distribution of carbon atoms on either side of
functional group.
CH3CH2-O-CH2CH3
CH3-O-CH2CH2CH3
Diethylether
Methylpropyl ether
H H
CH3CH2-N-CH2CH3
CH3CH2CH2-N-CH3
Diethylamine
Methyl ropyl amine
Tautomerism:
Type of functional isomerism in which the isomers are in
dynamic equilibrium with each other.. Most coomonly they are also called as Keto or Enol form
keto= ketone group
enol= alcohol group
Example: