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 eight-carbon alkene that would yield the specified compound after treatment with ozone followed by dimethyl sulfide is 2-octene. The treatment with ozone followed by dimethyl sulfide would lead to the cleavage of the double bond, forming two aldehyde groups.
Explanation:
- Ozonolysis of Alkenes:
When an alkene undergoes ozonolysis, the ozone molecule adds across the double bond, resulting in the formation of an unstable ozonide. This ozonide is then reduced, typically with a reducing agent such as dimethyl sulfide (DMS), to give two carbonyl compounds, which are generally aldehydes or ketones depending on the substitution pattern of the alkene. - The Structure of 2-Octene:
The compound given, which is derived from ozonolysis, has a specific structure: two aldehyde groups at the ends of the molecule. This implies that the starting alkene must have a structure where the double bond is positioned such that cleavage by ozone yields two aldehyde groups.
- In 2-octene, the double bond is located between the second and third carbons. This structure can be represented as CH₃-CH₂-CH=CH-CH₂-CH₂-CH₃ (with the double bond between the second and third carbons).
- Mechanism of the Reaction:
- When 2-octene undergoes ozonolysis, the double bond is cleaved, and the resulting ozonide intermediate will be reduced by dimethyl sulfide. This results in the formation of two aldehyde groups: one at the terminal carbon (carbon 1) and one at carbon 8 (the other end of the molecule).
- The cleavage yields octanal (an aldehyde with 8 carbons, one at each end of the cleaved alkene).
- No Other Products:
The ozonolysis of 2-octene will exclusively yield octanal and no other products. This is because ozonolysis only cleaves the double bond and produces aldehydes, and the structure of 2-octene ensures that cleavage will yield exactly two octanal molecules.
Thus, the eight-carbon alkene in question is 2-octene, and ozonolysis followed by dimethyl sulfide would yield two molecules of octanal.