Constitutional isomers are compounds that have the same molecular formula but differ in the way their atoms are connected. For the molecular formula C4H9Br, there are four distinct constitutional isomers. Below, I will describe each isomer along with diagrams:
1. 1-Bromobutane
This isomer features the bromine atom attached to the first carbon of a straight-chain butane.
2. 2-Bromobutane
In this structure, the bromine is attached to the second carbon of the butane chain.
3. 1-Bromo-2-methylpropane
This isomer has a bromine atom on the first carbon of a propane chain, with a methyl group attached to the second carbon.
4. 2-Bromo-2-methylpropane
Here, the bromine is bonded to the second carbon in a branched chain, where two methyl groups are attached to that same carbon.
These four isomers highlight the diversity in structural arrangement that can arise from the same molecular formula, showcasing the concept of constitutional isomerism.