Structural Isomerism
Hardchemistry
The total number of structural isomers possible for alcohols with the molecular formula C₄H₁₀O is:
Select the correct option:
Solution
Incorrect! Answer:
4
For molecular formula C₄H₁₀O restricted to alcohols (one –OH group on a C4 carbon skeleton), we enumerate systematically:
- Butan-1-ol: CH₃CH₂CH₂CH₂OH — primary, unbranched chain
- Butan-2-ol: CH₃CH₂CH(OH)CH₃ — secondary, unbranched chain
- 2-Methylpropan-1-ol: (CH₃)₂CHCH₂OH — primary, branched chain
- 2-Methylpropan-2-ol: (CH₃)₃COH — tertiary, branched chain No other arrangements are possible within a C4 skeleton with one –OH. Note that C₄H₁₀O ethers (e.g., diethyl ether, methyl propyl ether) are not alcohols and are excluded. Therefore, exactly 4 structural isomers exist as alcohols.
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About This Question
- Subject
- chemistry
- Chapter
- some basic principles of organic chemistry
- Topic
- structural isomerism
- Difficulty
- Hard
- Year
- 2025
Solution
Correct Answer:
4
For molecular formula C₄H₁₀O restricted to alcohols (one –OH group on a C4 carbon skeleton), we enumerate systematically:
- Butan-1-ol: CH₃CH₂CH₂CH₂OH — primary, unbranched chain
- Butan-2-ol: CH₃CH₂CH(OH)CH₃ — secondary, unbranched chain
- 2-Methylpropan-1-ol: (CH₃)₂CHCH₂OH — primary, branched chain
- 2-Methylpropan-2-ol: (CH₃)₃COH — tertiary, branched chain No other arrangements are possible within a C4 skeleton with one –OH. Note that C₄H₁₀O ethers (e.g., diethyl ether, methyl propyl ether) are not alcohols and are excluded. Therefore, exactly 4 structural isomers exist as alcohols.
This hard difficulty chemistry question is from the chapter some basic principles of organic chemistry, covering the topic of structural isomerism. It appeared in the 2025 exam.
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