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 Halogenation

Organic Chemistry

10. Addition Reactions

Alkyne Halogenation

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4:39 minutes

Problem 34d

Textbook Question

What reagents should be used to carry out the following syntheses?

Verified step by step guidance

Identify the starting material and the product. The starting material is an alkyne, and the product is an aldehyde.

Recognize that the transformation involves converting an alkyne to an aldehyde. This suggests a hydration reaction that stops at the aldehyde stage.

Consider the use of hydroboration-oxidation, which is a common method to convert terminal alkynes to aldehydes. This involves two main steps: hydroboration followed by oxidation.

For hydroboration, use a reagent like disiamylborane or 9-BBN (9-borabicyclo[3.3.1]nonane) to add across the triple bond in a syn addition manner.

For the oxidation step, use hydrogen peroxide (H₂O₂) in the presence of a base like sodium hydroxide (NaOH) to convert the boron intermediate into the aldehyde.

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Key Concepts

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

Hydroboration-Oxidation

Hydroboration-oxidation is a two-step reaction process used to convert alkenes or alkynes into alcohols. In the first step, an alkene or alkyne reacts with borane (BH3) to form an organoborane intermediate. The second step involves oxidation, typically using hydrogen peroxide (H2O2) in a basic solution, which converts the organoborane into an alcohol, resulting in anti-Markovnikov addition.

Reagents for Hydroboration

The primary reagents for hydroboration include borane (BH3) or its derivatives, such as diborane (B2H6), which can effectively add across the triple bond of an alkyne. These reagents are crucial for the initial step of the hydroboration process, allowing for the formation of the organoborane intermediate that will later be oxidized to yield the alcohol product.

Alkyne Reactivity

Alkynes are reactive compounds due to the presence of a carbon-carbon triple bond, which is more reactive than double or single bonds. This reactivity allows alkynes to undergo various addition reactions, including hydroboration. Understanding the reactivity of alkynes is essential for predicting the products of reactions and selecting appropriate reagents for synthesis.