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

12. Alcohols, Ethers, Epoxides and Thiols

Making Ethers - Acid-Catalyzed Alkoxylation

Organic Chemistry

12. Alcohols, Ethers, Epoxides and Thiols

Making Ethers - Acid-Catalyzed Alkoxylation

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3:57 minutes

Problem 76a

Textbook Question

a. Propose a mechanism for the following reaction (show all curved arrows):

Verified step by step guidance

Step 1: Protonation of the alcohol group - The sulfuric acid (H₂SO₄) acts as a strong acid and donates a proton (H⁺) to the hydroxyl group (-OH) of ethanol, forming a protonated alcohol (CH₃CH₂OH₂⁺). This step increases the electrophilicity of the alcohol, making it a better leaving group.

Step 2: Formation of the carbocation - The protonated alcohol undergoes elimination of water (H₂O), leaving behind a carbocation intermediate. This carbocation is formed on the carbon attached to the hydroxyl group.

Step 3: Electrophilic addition of the alkene - The alkene (2-methyl-2-butene) acts as a nucleophile and attacks the carbocation, forming a new bond between the carbocation and one of the carbons in the double bond of the alkene. This step generates a new intermediate.

Step 4: Rearrangement and stabilization - If necessary, the intermediate may undergo rearrangement to form a more stable carbocation. This is common in reactions involving carbocations, as they tend to stabilize through hydride or alkyl shifts.

Step 5: Deprotonation to form the final product - A base (often the bisulfate ion, HSO₄⁻, from the sulfuric acid) removes a proton from the intermediate, leading to the formation of the ether product. The final product is an ether with the alkyl group from the alcohol and the alkene combined.

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Key Concepts

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

Acid-Catalyzed Reactions

Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In this context, sulfuric acid (H2SO4) acts as a catalyst, protonating the alcohol to enhance its electrophilicity. This step is crucial for facilitating the nucleophilic attack by the alkene, leading to ether formation.

Nucleophilic Attack

Nucleophilic attack is a fundamental concept in organic chemistry where a nucleophile, a species with a high electron density, attacks an electrophile, a species with a low electron density. In this reaction, the alkene acts as a nucleophile, attacking the protonated alcohol, which is now a better electrophile due to protonation, resulting in the formation of an ether.

Curved Arrows in Mechanisms

Curved arrows are used in organic chemistry to illustrate the movement of electrons during chemical reactions. They indicate the flow of electron pairs from nucleophiles to electrophiles or from bonds to atoms. Accurately depicting these arrows is essential for understanding the mechanism of the reaction, as they show how bonds are formed and broken throughout the process.

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Related Practice

Textbook Question

Show how each of the following compounds can be synthesized from an alkene:

Textbook Question

a. Draw the product or products that will be obtained from the reaction of cis-2-butene and trans-2-butene with each of the following reagents. If a product can exist as stereoisomers, show which stereoisomers are formed.

8. CH₃OH + H₂SO₄

b. With which reagents do the two alkenes react to form different products?

Textbook Question

How could the following compounds be prepared using an alkene as one of the starting materials?

Textbook Question

b. Which step is the rate-determining step?

Textbook Question

What is the major product of each of the following reactions?

Textbook Question

How could the following compound be prepared using an alkene as one of the starting materials?

Textbook Question

Propose a mechanism for the following reaction (remember to use curved arrows to show the movement of electrons from the nucleophile to the electrophile):

Textbook Question

c. What is the electrophile in the first step?

d. What is the nucleophile in the first step?

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