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

Alkyne Hydration

Organic Chemistry

10. Addition Reactions

Alkyne Hydration

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1:34 minutes

Problem 37

Textbook Question

Draw the ketone(s) you would expect to form by reacting the following alkynes under the conditions of oxymercuration: (a) 6-methyloct-1-yne, (b) 1,10-dicyclohexyldec-5-yne, and (c) 5-phenylhex-2-yne.

Verified step by step guidance

Understand the reaction: Oxymercuration of alkynes involves the addition of water across the triple bond in the presence of mercuric sulfate (HgSO₄) and sulfuric acid (H₂SO₄), leading to the formation of ketones.

Identify the alkyne structure: For each alkyne, locate the triple bond and determine the carbon atoms involved. This will help in predicting the site of ketone formation.

Apply Markovnikov's rule: In oxymercuration, the addition of water follows Markovnikov's rule, where the hydroxyl group (OH) adds to the more substituted carbon atom of the triple bond, leading to the formation of an enol intermediate.

Tautomerization: The enol intermediate formed will undergo tautomerization, a process where the enol rearranges to form a more stable ketone. This involves the migration of a hydrogen atom and the shift of a double bond.

Draw the ketone structures: For each alkyne, draw the resulting ketone structure after tautomerization. Ensure that the ketone carbonyl group (C=O) is correctly positioned according to the Markovnikov addition.

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Key Concepts

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

Oxymercuration of Alkynes

Oxymercuration is a reaction that converts alkynes into ketones using mercuric sulfate (HgSO₄) and sulfuric acid (H₂SO₄) in the presence of water. The reaction proceeds via the formation of an enol intermediate, which tautomerizes to form a ketone. This process is regioselective, typically resulting in the Markovnikov addition of water across the triple bond.

Markovnikov's Rule

Markovnikov's Rule states that in the addition of HX to an unsymmetrical alkene or alkyne, the hydrogen atom will attach to the carbon with more hydrogen atoms, while the halide or other group will attach to the carbon with fewer hydrogen atoms. In the context of oxymercuration, this rule helps predict the major product by determining the position of the hydroxyl group before tautomerization to the ketone.

Tautomerization

Tautomerization is the chemical process where an enol (a compound with a hydroxyl group attached to a carbon-carbon double bond) rearranges to form a ketone or aldehyde. This is a crucial step in the oxymercuration of alkynes, where the initially formed enol intermediate rapidly converts to a more stable ketone, completing the transformation of the alkyne to the ketone product.

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Related Practice

Textbook Question

How can the following compounds be synthesized, starting with a hydrocarbon that has the same number of carbons as the desired product?

Multiple Choice

Predict the major, organic product for the following reaction.

Textbook Question

Only one alkyne forms an aldehyde when it undergoes the mercuric-ion-catalyzed addition of water. Identify the alkyne.

Textbook Question

Show how you would accomplish the following synthetic transformations. Show all intermediates.

h. hex-1-yne → hexan-2-one, CH₃COCH₂CH₂CH₂CH₃

Textbook Question

Show how you would synthesize octanal from each compound. You may use any necessary reagents.

(e) 1-bromohexane

Textbook Question

Show how you would synthesize octanal from each compound. You may use any necessary reagents.

Textbook Question

Hydration of alkynes (via oxymercuration) gives good yields of single compounds only with symmetrical or terminal alkynes. Show what the products would be from hydration of each compound.

b. hex-2-yne

Textbook Question

Hydration of alkynes (via oxymercuration) gives good yields of single compounds only with symmetrical or terminal alkynes. Show what the products would be from hydration of each compound.

a. hex-3-yne

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