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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Problem 39d

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)

Verified step by step guidance

Analyze the given compound: The structure is an aldehyde with a cyclopropyl group attached to a chain of three carbons. The aldehyde functional group is located at the terminal carbon.

Recall the general method for synthesizing aldehydes from alkynes: Terminal alkynes can undergo hydroboration-oxidation to yield aldehydes. This reaction involves the addition of a borane reagent followed by oxidation with hydrogen peroxide in a basic solution.

Determine the precursor alkyne: The precursor alkyne must have the same carbon skeleton as the target aldehyde. In this case, the alkyne should be a terminal alkyne with the cyclopropyl group attached to the same position as in the target molecule.

Outline the reaction conditions: Use a hydroboration reagent such as disiamylborane (Sia₂BH) or 9-BBN to ensure regioselective addition to the terminal carbon of the alkyne. Follow this step with oxidation using H₂O₂ and NaOH to convert the intermediate organoborane into the aldehyde.

Verify the feasibility: Since hydroboration-oxidation of terminal alkynes is a well-established method for synthesizing aldehydes in good yield (>50%), this approach is feasible for the given compound.

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Key Concepts

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

Alkynes and Their Reactivity

Alkynes are hydrocarbons containing at least one carbon-carbon triple bond. They are highly reactive due to the presence of this triple bond, which can undergo various reactions such as electrophilic addition, hydrogenation, and nucleophilic attack. Understanding the reactivity of alkynes is crucial for determining how they can be transformed into other functional groups, such as ketones and aldehydes.

Hydroboration-Oxidation

Hydroboration-oxidation is a two-step reaction process used to convert alkynes into aldehydes or ketones. In the first step, the alkyne reacts with diborane (B2H6) to form an organoborane intermediate, which is then oxidized with hydrogen peroxide (H2O2) in the presence of a base. This method is particularly useful for synthesizing aldehydes from terminal alkynes and ketones from internal alkynes.

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 is essential for predicting the outcome of reactions involving alkynes, especially when determining the regioselectivity of the product formed during the synthesis of ketones and aldehydes from alkynes.

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Related Practice

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

Textbook Question

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

(c)

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

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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)

Key Concepts

Alkynes and Their Reactivity

Hydroboration-Oxidation

Markovnikov's Rule

Watch next

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)