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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3:39 minutes

Problem 15c

Textbook Question

Which alkyne should be used for the synthesis of each of the following ketones?
c.

Verified step by step guidance

Step 1: Analyze the target ketone structure. The given ketone has a methyl group (CH₃) attached to the carbonyl group (C=O), and the other side of the carbonyl group is bonded to a cyclohexyl group (a six-membered ring).

Step 2: Recall the general mechanism for synthesizing ketones from alkynes. Ketones can be synthesized via the hydration of alkynes using acid-catalyzed conditions (H₂SO₄, H₂O) and a mercury(II) sulfate catalyst (HgSO₄). This reaction follows Markovnikov's rule, where the OH group adds to the more substituted carbon of the triple bond.

Step 3: Determine the alkyne precursor. To form the given ketone, the alkyne must have a triple bond between the carbon that will become the carbonyl group and the carbon that will be bonded to the cyclohexyl group. The alkyne should be 1-cyclohexyl-1-propyne.

Step 4: Explain the hydration process. When 1-cyclohexyl-1-propyne undergoes hydration in the presence of H₂SO₄ and HgSO₄, the OH group adds to the more substituted carbon (the carbon bonded to the cyclohexyl group), and the triple bond is converted into a double bond, forming an enol intermediate. The enol tautomerizes to the ketone.

Step 5: Verify the structure. After hydration and tautomerization, the final product matches the target ketone structure, with the methyl group and cyclohexyl group attached to the carbonyl carbon.

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Key Concepts

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

Alkynes

Alkynes are hydrocarbons that contain at least one carbon-carbon triple bond. They are unsaturated compounds and can participate in various chemical reactions, including addition reactions. Understanding the structure and reactivity of alkynes is crucial for predicting the products of reactions involving them, especially in synthetic pathways.

Ketone Synthesis

Ketones are organic compounds characterized by a carbonyl group (C=O) flanked by two carbon atoms. The synthesis of ketones often involves the reaction of alkynes with specific reagents, such as water in the presence of a catalyst, to yield the desired ketone. Familiarity with the mechanisms of these reactions is essential for determining the appropriate alkyne for a given ketone.

Reagents and Reaction Conditions

The choice of reagents and reaction conditions significantly influences the outcome of organic reactions. For synthesizing ketones from alkynes, reagents like water, acids, or specific catalysts are often employed. Understanding how these factors affect the reaction pathway is vital for successfully identifying the correct alkyne for the synthesis of the desired ketone.

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Related Practice

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

Textbook Question

Predict the reagents or reactant(s) necessary to complete the following syntheses.

(c)

Textbook Question

For each of the following ketones/aldehydes, indicate whether it is possible to synthesize it from an alkyne as the only compound in good (> 50%) yield. If so, how would you do it?

(d)

Textbook Question

Which alkyne should be used for the synthesis of each of the following ketones?

Textbook Question

Show how each of the following compounds can be prepared using the given starting material, any needed inorganic reagents, and any organic compound that has no more than four carbons:

Textbook Question

What ketones are formed from the acid-catalyzed hydration of 3-heptyne?

Textbook Question

What are products of the following reactions?

Textbook Question

When pent-2-yne reacts with mercuric sulfate in dilute sulfuric acid, the product is a mixture of two ketones. Give the structures of these products, and use mechanisms to show how they are formed.

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Which alkyne should be used for the synthesis of each of the following ketones?c.

Key Concepts

Alkynes

Ketone Synthesis

Reagents and Reaction Conditions

Watch next

Which alkyne should be used for the synthesis of each of the following ketones?
c.