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

Previous problemNext problem

5:43 minutes

Problem 14

Textbook Question

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

Verified step by step guidance

Step 1: Understand the reaction type. The acid-catalyzed hydration of an alkyne involves the addition of water (H₂O) across the triple bond in the presence of an acid catalyst, typically H₂SO₄, and often with Hg²⁺ as a co-catalyst. This reaction follows Markovnikov's rule and results in the formation of a ketone via an enol intermediate.

Step 2: Identify the structure of 3-heptyne. 3-heptyne is a seven-carbon alkyne with the triple bond located between carbons 3 and 4. Its structure can be written as CH₃-CH₂-C≡C-CH₂-CH₂-CH₃.

Step 3: Apply Markovnikov's rule. When water adds to the triple bond, the hydroxyl group (-OH) will attach to the more substituted carbon (C4 in this case), while the hydrogen (H) will attach to the less substituted carbon (C3). This results in the formation of an enol intermediate.

Step 4: Understand tautomerization. The enol intermediate (a compound with a hydroxyl group directly bonded to a carbon-carbon double bond) is not stable under acidic conditions. It undergoes keto-enol tautomerization, where the double bond shifts, and the hydroxyl group is converted into a carbonyl group (C=O), forming a ketone.

Step 5: Determine the product. The ketone formed will have the carbonyl group (C=O) on the more substituted carbon (C4). The final product is 4-heptanone, which is the ketone derived from the hydration of 3-heptyne.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

Acid-Catalyzed Hydration

Acid-catalyzed hydration is a chemical reaction where an alkene or alkyne reacts with water in the presence of an acid catalyst, typically resulting in the formation of an alcohol. In the case of alkynes, this process involves the addition of water across the triple bond, leading to the formation of a carbonyl compound, such as a ketone, after rearrangement and tautomerization.

Alkyne Structure and Reactivity

Alkynes are hydrocarbons that contain at least one carbon-carbon triple bond. The structure of 3-heptyne, specifically, indicates that it has a triple bond between the third and fourth carbon atoms in a seven-carbon chain. This unique structure influences its reactivity, allowing it to undergo hydration to form ketones, depending on the position of the triple bond and the conditions of the reaction.

Tautomerization

Tautomerization is a chemical process where a compound exists in two interconvertible forms, typically involving the migration of a hydrogen atom and a shift in the position of a double bond. In the context of the hydration of 3-heptyne, the initial product is an enol, which quickly tautomerizes to form a more stable ketone. Understanding this process is crucial for predicting the final products of the reaction.

Watch next

Master Vinyl alcohols yield tautomers. with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

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

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 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.

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.

e. 3-methylcyclodecyne

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.

c. hex-1-yne

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap