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Ch.8 - Reactions of Alkenes
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
All textbooksWade 9th EditionCh.8 - Reactions of AlkenesProblem 75
Chapter 8, Problem 75

Ozonolysis can be applied selectively to different types of carbon–carbon double bonds. The compound shown below contains two vinyl ether double bonds, which are electron-rich because of the electron-donating alkoxy groups. Ozone reacts more quickly with electron-rich double bonds and more slowly with hindered double bonds. At −78 °C, this compound quickly adds two equivalents of ozone. Immediate reduction of the ozonide gives a good yield of a single product. Show the expected ozonolyis product, and label the functional groups produced, some of which are not typical from ozonolysis of simple alkenes.
Chemical structure of a compound with two vinyl ether double bonds, showing ozonolysis reaction conditions and expected product.

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Step 1: Analyze the structure of the compound provided. The molecule contains two vinyl ether double bonds, which are electron-rich due to the electron-donating alkoxy groups (-OCH3). These double bonds are more reactive toward ozone compared to hindered or less electron-rich double bonds.
Step 2: Understand the reaction conditions. Ozonolysis involves the addition of ozone (O3) to the double bonds at low temperatures (-78 °C). The reaction proceeds by forming an ozonide intermediate, which is then reduced using dimethyl sulfide ((CH3)2S) to yield the final products.
Step 3: Predict the cleavage of the double bonds. Ozone cleaves the carbon-carbon double bonds, resulting in the formation of carbonyl-containing products. For vinyl ethers, ozonolysis typically produces aldehydes or ketones, along with other functional groups depending on the substituents.
Step 4: Identify the products formed. Each double bond in the molecule will be cleaved, and the electron-donating alkoxy groups will influence the type of carbonyl compounds formed. The expected products will include aldehydes and/or ketones, and the functional groups should be labeled accordingly.
Step 5: Summarize the functional groups in the product. After ozonolysis and reduction, the molecule will yield a single product containing multiple carbonyl groups (aldehydes and/or ketones). These functional groups are characteristic of ozonolysis reactions, but the presence of alkoxy groups may lead to atypical products compared to simple alkenes.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ozonolysis

Ozonolysis is a reaction involving the cleavage of carbon-carbon double bonds (alkenes) using ozone (O3). This reaction typically results in the formation of ozonides, which can be further reduced to yield carbonyl compounds such as aldehydes or ketones. The reaction is particularly useful for transforming alkenes into more functionalized products, and the selectivity of ozonolysis can vary based on the electronic and steric properties of the double bonds involved.
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Electron-Rich Double Bonds

Electron-rich double bonds, such as those found in vinyl ethers, are more reactive towards ozone due to the presence of electron-donating groups. These groups enhance the nucleophilicity of the double bond, facilitating a faster reaction with ozone compared to electron-poor or hindered double bonds. Understanding the reactivity of different double bonds is crucial for predicting the products of ozonolysis and the overall reaction mechanism.
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Functional Group Transformation

Ozonolysis often leads to the formation of functional groups that are not typically associated with simple alkenes. In this reaction, the cleavage of the double bond can produce carbonyl compounds, such as aldehydes and ketones, as well as other functional groups depending on the substituents present. Recognizing these transformations is essential for accurately predicting the final products of ozonolysis and understanding the implications for further chemical reactivity.
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