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

21. Aldehydes and Ketones: Nucleophilic Addition

Imine vs Enamine

Organic Chemistry

21. Aldehydes and Ketones: Nucleophilic Addition

Imine vs Enamine

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4:13 minutes

Problem 68b

Textbook Question

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

Verified step by step guidance

Step 1: Protonation of the epoxide ring - The reaction begins with the protonation of the oxygen atom in the epoxide ring by HCl. This step increases the electrophilicity of the epoxide, making it more susceptible to nucleophilic attack. The oxygen atom gains a positive charge, forming an oxonium ion.

Step 2: Nucleophilic attack by methanol (CH₃OH) - Methanol acts as a nucleophile and attacks one of the carbon atoms in the protonated epoxide ring. This attack occurs at the less sterically hindered carbon atom, leading to the opening of the epoxide ring.

Step 3: Formation of the intermediate - After the nucleophilic attack, a new bond is formed between the methanol oxygen and the carbon atom of the epoxide. The intermediate formed has a positively charged oxygen atom from the methanol group.

Step 4: Deprotonation of the intermediate - A base (possibly the chloride ion from HCl) removes the extra proton from the methanol group, neutralizing the positive charge and forming the final product.

Step 5: Final product - The reaction yields a methoxy-substituted cyclic ether, where the methanol group is attached to the carbon that was part of the epoxide ring.

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Key Concepts

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

Nucleophilic Addition

Nucleophilic addition is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophilic carbon atom, leading to the formation of a new bond. In this reaction, methanol (CH3OH) acts as the nucleophile, attacking the electrophilic carbon of the cyclic compound. This process is crucial for understanding how various functional groups can be introduced into organic molecules.

Protonation and Catalysis

Protonation is the addition of a proton (H+) to a molecule, which can enhance its electrophilicity. In this reaction, HCl serves as a catalyst, protonating the oxygen atom of the cyclic compound, making it more susceptible to nucleophilic attack. This step is essential for facilitating the reaction and is a common strategy in acid-catalyzed organic reactions.

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, providing insight into the intermediates and transition states involved. Understanding the mechanism of the nucleophilic addition in this reaction is vital for predicting the behavior of similar reactions and for designing synthetic pathways in organic chemistry.

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