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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7:10 minutes

Problem 15a,b

Textbook Question

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

Verified step by step guidance

Step 1: Recognize that ketones can be synthesized from alkynes via hydration reactions. In the presence of water, an alkyne undergoes addition to form an enol intermediate, which tautomerizes into a ketone.

Step 2: Identify the structure of the ketone provided in part (a). The ketone has a methyl group on one side and another methyl group on the other side of the carbonyl group. This suggests that the alkyne used should have two methyl groups attached to the triple bond.

Step 3: For part (a), propose the alkyne structure that would lead to the given ketone. The alkyne should be symmetrical, such as 2-butyne (CH₃C≡CCH₃), because hydration of this alkyne will yield the desired ketone.

Step 4: Identify the structure of the ketone provided in part (b). The ketone has ethyl groups on both sides of the carbonyl group. This suggests that the alkyne used should have two ethyl groups attached to the triple bond.

Step 5: For part (b), propose the alkyne structure that would lead to the given ketone. The alkyne should be symmetrical, such as 3-hexyne (CH₃CH₂C≡CCH₂CH₃), because hydration of this alkyne will yield the desired ketone.

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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 and for their use in organic synthesis.

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 acid or base, to yield the desired ketone. Familiarity with the mechanisms of these reactions is essential for determining which alkyne to use for synthesizing a particular ketone.

Markovnikov's Rule

Markovnikov's Rule states that in the addition of HX to an alkene or alkyne, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This principle helps predict the regioselectivity of reactions involving alkynes, which is important when determining the correct alkyne to use for synthesizing specific ketones based on the structure of the desired product.

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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.

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

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?

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