Isomerism
- Isomerism is a consequence of the directional nature of the covalent bond.
- This results in atoms arranged in different positions are spatial arrangements leading to isomers.
- Isomers are compounds, which have the same molecular formula but different structure or spatial arrangement (configuration).
Classification
Structural Isomersim (Constitutional isomerism)
Functional isomers have the same molecular formula but different functional group. Both H3C-O-CH3 and CH3CH2OH have the smae moleuclar formula C2H6O but different functional group, one is an ether and the other is an alcohol. Similarly acetone and propanaldehyde (CH3COCH3 and CH3CH2CHO) are a pair of functional isomers.
Positional isomers have the same molecular formula but differ in the position of attachment of the functional group or substitutent. 1-Chloropropane and 2-Chloroproane (CH3CH2CH2Cl and CH3CHClCH3 ) are a pair of positional isomers so are 2-Butene and 1-Butene.
Chain isomers have the same molecular formula but different chain length. Pentane and 2-Methyl butane is such a pair, the former has five carbon atoms in a single chain while the later has four cabons in a single chain and the fifth is attached as a branch.
