Draw the structure of an eight-carbon alkene that would yield the following compound (and no others) after treatment with ozone followed by dimethyl sulfide.
The Correct Answer and Explanation is:
To provide the correct structure and explanation, we need to:
- Analyze the ozonolysis product given.
- Reconstruct the alkene that would yield only this compound.
- Explain how ozonolysis works and why this particular structure is correct.
🔬 Understanding Ozonolysis:
Ozonolysis is a cleavage reaction where an alkene reacts with ozone (O₃), breaking the C=C double bond and forming carbonyl compounds (aldehydes or ketones). In a reductive workup using dimethyl sulfide (DMS), the ozonide intermediate is reduced to give ketones and/or aldehydes.
If the product of ozonolysis is only one compound, it means the original alkene was symmetrical and gave identical fragments upon cleavage.
🎯 Given Compound (Product of Ozonolysis):
Let’s assume the given ozonolysis product is only:
2 molecules of butanal (CH₃CH₂CH₂CHO)
Each has 4 carbon atoms, so the total carbon number is 8 → the original alkene has 8 carbon atoms.
✅ Correct Alkene:
To get 2 butanal molecules, the alkene must be:
3-octene
Structure of 3-octene:
CH3–CH2–CH=CH–CH2–CH2–CH3
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(double bond between C3 and C4)
This is a symmetrical internal alkene.
Upon ozonolysis:
- Cleavage occurs at the double bond between C3 and C4.
- Both sides form butanal (CH₃CH₂CH₂CHO).
🧠 Why This Is Correct:
- Symmetry: 3-octene is symmetric, so it produces only one ozonolysis product.
- Carbon count: 4 + 4 = 8 → matches the original molecule’s carbon count.
- Product match: Butanal is the aldehyde expected from cleavage between two methylene groups.
Other alkenes (like 1-octene or 4-octene) would yield different combinations of aldehydes and/or ketones.
✅ Final Answer:
The correct alkene is 3-octene.
Structure:
CH3–CH2–CH=CH–CH2–CH2–CH3
