Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

10. Addition Reactions

Ozonolysis

Organic Chemistry

10. Addition Reactions

Ozonolysis

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3:32 minutes

Problem 64c

Textbook Question

What reagents are needed to carry out the following syntheses?

Verified step by step guidance

Step 1: Analyze the first transformation (i). The starting material is an epoxide, and the product is an alkene. This suggests that the reaction involves the opening of the epoxide ring followed by elimination. A common reagent for this transformation is a strong base, such as sodium ethoxide (NaOEt), which can facilitate the elimination process.

Step 2: For the first transformation (i), the epoxide ring is opened under basic conditions, and the elimination occurs to form the double bond in the cyclopentyl group. Ensure the base is strong enough to deprotonate the intermediate and drive the elimination reaction.

Step 3: Analyze the second transformation (ii). The starting material is an alkene, and the product is a ketone. This suggests an oxidation reaction. A common reagent for this transformation is ozone (O₃) followed by a reductive workup, such as dimethyl sulfide (DMS) or zinc (Zn) with acetic acid.

Step 4: For the second transformation (ii), the alkene undergoes ozonolysis. The double bond is cleaved, and the resulting fragments are oxidized to form a ketone. Ensure the reductive workup is performed to avoid overoxidation.

Step 5: Verify the reagents and conditions for both transformations. For (i), use a strong base like NaOEt to open the epoxide and eliminate to form the alkene. For (ii), use ozone (O₃) followed by a reductive workup (e.g., DMS or Zn/AcOH) to cleave the alkene and form the ketone.

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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 alkenes or alkynes using ozone (O3) to form carbonyl compounds, such as aldehydes and ketones. The process typically occurs in two steps: first, the alkene reacts with ozone to form a molozonide, which rearranges to form ozonide. The ozonide is then reduced, often using reagents like zinc and acetic acid or dimethyl sulfide, to yield the final carbonyl products.

Reagents for Ozonolysis

The reagents commonly used in ozonolysis include ozone (O3) for the initial reaction and a reducing agent such as zinc (Zn) in acetic acid or dimethyl sulfide (DMS) for the second step. These reagents facilitate the conversion of the ozonide intermediate into stable carbonyl compounds, allowing for the identification and synthesis of specific products from the original alkene.

Mechanism of Ozonolysis

The mechanism of ozonolysis involves the electrophilic attack of ozone on the double bond of an alkene, leading to the formation of a cyclic molozonide. This intermediate undergoes rearrangement to form a more stable ozonide, which is then cleaved by the reducing agent to yield carbonyl compounds. Understanding this mechanism is crucial for predicting the products of ozonolysis and for designing synthetic pathways in organic chemistry.

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