Isomerism

         Compounds having same molecular formula but possessing different properties. This phenomenon is known as isomerism. There are two types of isomerisms.
                        ( i ) Structural isomerism.
                       ( ii ) Stereoisomerism.

Structural isomerism:
         Isomers which have the same molecular formula but differ in their structures. It is otherwise known as constitutional isomerism. It is opposed to stereoisomeris. Different types of structural isomers are given below.

• Position isomerism.
• Chain isomerism.
• Functional isomerism.

Position isomerism:

         In position isomerism a functional group or other substituents changes position on a parent ( main carbon chain ) structure. It is otherwise known as regioisomerism.

Example:

Chain isomerism:

        Chain isomers differ in the structure of their chain ( carbon skeleton ). It is otherwise known as skeletal isomerism.

Example:

But pentane  C₅H₁₂  has three isomers.

Functional isomerism:

           Isomers have the same molecular formula but different functional groups are known as functional isomerism.

Example:  C₃H₆O 

Example: C₂H₆O

 CH₃ – O – CH₃    diethyl ether.

Carbon-oxygen-carbon chain functionality is called Ether.

 CH₃ CH₂ – O – H Ethanol.

Carbon-oxygen-hydrogen functionality is called Alcohol.