Structure 3.2.6
Structural Isomers
Molecules with the same molecular formula but different connectivities (structural formulas).
Chirality (Optical Isomerism)
Non-Superimposable Mirror Images
Like your left and right hands. They contain the exact same atoms connected to the same central carbon, but arranged differently in 3D space.
Types of Structural Isomerism
1. Chain Isomerism
The carbon skeleton is arranged differently (branching).
Pentane
vs
2-methylbutane
vs
2-methylbutane
2. Positional Isomerism
The functional group stays the same but moves to a different carbon.
Pentan-1-ol
vs
Pentan-2-ol
vs
Pentan-2-ol
3. Functional Group Isomerism
The atoms are rearranged to form a different family of compound.
Ethanol (Alcohol)
vs
Methoxymethane (Ether)
vs
Methoxymethane (Ether)
Common Functional Group Isomer Pairs
- Alcohols ā Ethers (e.g., )
- Aldehydes ā Ketones (e.g., )
- Carboxylic Acids ā Esters (e.g., )
- Alkenes ā Cycloalkanes (e.g., )