Define the term ‘structural’ isomerism’. Explain why propane cannot exhibit this property. Draw the structure of possible isomers of butane, C4H10.
Structural isomerism : Molecules having same molecular formula but different structure are said to be structural isomers.
Propane has the chemical formula C3Hg and it is represented as CH3—CH2—CH3. In alkanes, isomerism arises when a particular compound can be represented in the form of both straight chain and branced chain. Also, the branching cannot be done from the first or the last carbon atom of the structure.
The structural formulae of propane shows that they do not have sufficient number of carbon atoms to exist in the form of branched isomer. Hence, they donot exhibit structural isomerism.