Exam Style Question - 3

Question: Draw and name all the structural isomers with the molecular formula C₅H₁₂.All the isomers are alkanes, so the only possible type of isomerism is chain isomerism. Start with the longest chain and shorten it one carbon at a time.Five carbons in a chain: pentane, CH₃CH₂CH₂CH₂CH₃.Four carbons in a chain with a methyl branch: 2-methylbutane, CH₃CH(CH₃)CH₂CH₃. Putting the methyl on carbon 3 gives the same molecule, so it is not a new isomer.Three carbons in a chain with two methyl branches: 2,2-dimethylpropane, C(CH₃)₄. There are therefore three chain isomers of C₅H₁₂.