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.

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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 solve this problem, we must determine the structure of the original alkene that, upon ozonolysis followed by reduction with dimethyl sulfide (DMS), produces only one specific compound — typically a single carbonyl compound (like an aldehyde or ketone). Since the product is not specified in the question, let’s assume we are to find a general case where ozonolysis of a specific eight-carbon alkene produces a single product and no mixture.

Correct Answer (Structure):

The correct eight-carbon alkene is:

4-octene (symmetrical, trans or cis)

Structure of 4-octene:

CH3-CH2-CH=CH-CH=CH-CH2-CH3  ❌ (not this; this is a diene)

CH3-CH2-CH2-CH=CH-CH2-CH2-CH3  ✅ (this is 4-octene)
       |
   This is symmetrical

Explanation (300+ words):

Ozonolysis is a chemical reaction where an alkene is cleaved at the carbon-carbon double bond (C=C) using ozone (O₃). When followed by reduction (commonly with dimethyl sulfide, DMS), it produces aldehydes and/or ketones, depending on the groups attached to the double bond.

In this question, we’re told that ozonolysis yields only one compound. This implies the original alkene must be symmetrical — because symmetrical alkenes give identical cleavage products on both sides of the double bond.

Let’s examine 4-octene:

Structure of 4-octene:

CH3–CH2–CH2–CH=CH–CH2–CH2–CH3
       (double bond between C4 and C5)

Upon ozonolysis and reduction:

  • The double bond between carbon 4 and carbon 5 is broken.
  • Each side becomes a carbonyl compound (specifically, butanal or butanone, depending on the substitution pattern).

Because 4-octene is symmetrical, both sides of the double bond are identical:

  • Left side: CH3–CH2–CH2– (C4)
  • Right side: –CH2–CH2–CH3 (C5)

This results in the formation of two identical molecules of the same aldehyde or ketone. There’s no mixture, only one compound is formed.

In contrast, if you used 1-octene, 2-octene, or 3-octene, the two sides of the double bond would be asymmetrical, leading to the formation of two different products upon ozonolysis, violating the condition of the question.

Conclusion:

✅ The correct structure is 4-octene:
CH₃–CH₂–CH₂–CH=CH–CH₂–CH₂–CH₃

It is the only eight-carbon alkene that is symmetrical, and upon ozonolysis with dimethyl sulfide, yields one and only one product — satisfying the conditions of the question.

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