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

25. Condensation Chemistry

Conjugate Addition

Organic Chemistry

25. Condensation Chemistry

Conjugate Addition

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6:36 minutes

Problem 98b

Textbook Question

Propose a mechanism for each of the following reactions:
b.

Verified step by step guidance

Step 1: Analyze the starting material and reagent. The starting material is a ketone (a cyclic aromatic ketone), and the reagent is methanethiol (CH₃SH). This suggests a nucleophilic addition reaction involving the sulfur atom of CH₃SH.

Step 2: Protonation of the ketone oxygen. The reaction likely begins with the protonation of the carbonyl oxygen by an acid catalyst (if present), increasing the electrophilicity of the carbonyl carbon.

Step 3: Nucleophilic attack by CH₃SH. The sulfur atom in CH₃SH acts as a nucleophile and attacks the electrophilic carbonyl carbon, forming a tetrahedral intermediate.

Step 4: Proton transfer and rearrangement. A proton transfer occurs, leading to the formation of a hydroxyl group (-OH) on the former carbonyl carbon and the attachment of the CH₃S group to the adjacent carbon.

Step 5: Final product formation. The aromaticity of the ring is restored, resulting in the final product where the hydroxyl group (-OH) and the thioether group (-SCH₃) are attached to the aromatic ring system.

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Key Concepts

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

Conjugate Addition

Conjugate addition refers to the nucleophilic addition of a reagent to an α,β-unsaturated carbonyl compound. In this reaction, the nucleophile attacks the β-carbon, leading to the formation of a new bond while the double bond is shifted. This mechanism is crucial for understanding how nucleophiles like CH3SH can add to ketones or aldehydes, resulting in the formation of products with new functional groups.

Nucleophiles and Electrophiles

In organic chemistry, nucleophiles are species that donate an electron pair to form a chemical bond, while electrophiles are electron-deficient species that accept electron pairs. In the given reaction, CH3SH acts as a nucleophile due to the presence of the sulfur atom, which has a lone pair of electrons, allowing it to attack the electrophilic carbon of the ketone. Understanding the roles of nucleophiles and electrophiles is essential for predicting reaction mechanisms.

Reaction Mechanism

A reaction mechanism is a step-by-step description of the process by which reactants are converted into products. It outlines the sequence of bond-breaking and bond-forming events, including intermediates and transition states. Proposing a mechanism for the reaction shown involves identifying the nucleophilic attack, the formation of a tetrahedral intermediate, and the subsequent proton transfer, which leads to the final product. This understanding is vital for predicting the outcome of organic reactions.

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Propose a mechanism for each of the following reactions: b.

Key Concepts

Conjugate Addition

Nucleophiles and Electrophiles

Reaction Mechanism

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Propose a mechanism for each of the following reactions:
b.