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 :
The structure of an eight-carbon alkene that would yield a single product upon ozonolysis followed by dimethyl sulfide (DMS) must be carefully chosen based on symmetry and cleavage patterns. Ozonolysis of alkenes involves the cleavage of the double bond and formation of carbonyl-containing compounds (aldehydes or ketones).
Step 1: Understanding Ozonolysis
Ozonolysis consists of:
- Ozone (O₃) addition to the alkene, forming an unstable molozonide.
- Rearrangement into a more stable ozonide.
- Reductive workup with dimethyl sulfide (DMS), breaking the ozonide into aldehydes and/or ketones.
Step 2: Identifying the Product
Since the question states that only one compound forms, the alkene must be symmetrical and positioned such that both halves produce identical fragments.
Step 3: Choosing the Alkene
The most likely candidate is 4-octene, with a double bond at carbon 4: CH₃-CH₂-CH=CH-CH₂-CH₂-CH₃\text{CH₃-CH₂-CH=CH-CH₂-CH₂-CH₃}
Step 4: Predicting the Ozonolysis Product
Splitting 4-octene at C4=C5 will give two molecules of butanal (butyraldehyde, CH₃CH₂CH₂CHO).
Step 5: Confirmation
If any other alkene is chosen (such as 3-octene or 2-octene), it would yield two different carbonyl compounds, violating the problem’s requirement of yielding only one product.
Conclusion
The correct answer is 4-octene, as it cleaves into only butanal in ozonolysis with DMS.