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

Alcohol Nomenclature

Organic Chemistry

12. Alcohols, Ethers, Epoxides and Thiols

Alcohol Nomenclature

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4:39 minutes

Problem 19a,b

Textbook Question

Propose mechanisms to show the interchange of protons between ethanol molecules under
(a) acid catalysis.
(b) base catalysis.

Verified step by step guidance

Under acid catalysis: Begin by recognizing that the catalyst is an acid, which donates a proton (H⁺). The first step involves the protonation of one ethanol molecule (CH₃CH₂OH) by the acid, forming a positively charged oxonium ion (CH₃CH₂OH₂⁺).

Under acid catalysis: Next, another ethanol molecule acts as a nucleophile, using its lone pair of electrons on the oxygen atom to attack the oxonium ion. This results in the transfer of a proton from the oxonium ion to the second ethanol molecule, regenerating the neutral ethanol and forming a new oxonium ion.

Under base catalysis: Recognize that the catalyst is a base, which accepts a proton. The first step involves the deprotonation of one ethanol molecule (CH₃CH₂OH) by the base, forming an ethoxide ion (CH₃CH₂O⁻) and water (H₂O).

Under base catalysis: The ethoxide ion then acts as a strong base and abstracts a proton from another ethanol molecule, regenerating the neutral ethanol and forming a new ethoxide ion.

In both cases, the interchange of protons between ethanol molecules is facilitated by the catalyst (acid or base), which lowers the activation energy for the proton transfer and ensures the reaction proceeds efficiently.

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Key Concepts

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

Proton Transfer Mechanism

Proton transfer mechanisms involve the movement of protons (H⁺ ions) between molecules, which is fundamental in acid-base chemistry. In the context of ethanol, this process can be facilitated by either an acid or a base, leading to the formation of protonated or deprotonated species. Understanding this mechanism is crucial for analyzing how ethanol molecules interact under different catalytic conditions.

Acid Catalysis

Acid catalysis refers to the acceleration of a chemical reaction by the addition of an acid, which donates protons to the reactants. In the case of ethanol, an acid catalyst can protonate the hydroxyl group, enhancing the nucleophilicity of the ethanol molecule and facilitating proton transfer between ethanol molecules. This concept is essential for understanding how acids influence the reactivity of alcohols.

Base Catalysis

Base catalysis involves the use of a base to increase the rate of a reaction by accepting protons from the reactants. In the context of ethanol, a base can deprotonate the hydroxyl group, generating an alkoxide ion that can participate in proton transfer with other ethanol molecules. This concept is vital for comprehending how bases alter the behavior of alcohols in chemical reactions.

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