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

Hydroboration

Organic Chemistry

10. Addition Reactions

Hydroboration

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3:39 minutes

Problem 55d

Textbook Question

Suggest an alkene to undergo hydroboration–oxidation (1. BH₃ 2. NaOH, H₂O₂) to give exclusively the alcohols shown. Pay close attention to the relative (but not absolute) stereochemical outcome.
(d)

Verified step by step guidance

Identify the alcohol product(s) formed after hydroboration–oxidation. Hydroboration–oxidation of an alkene results in an anti-Markovnikov addition of water, where the hydroxyl group (-OH) attaches to the less substituted carbon of the double bond.

Analyze the stereochemistry of the alcohol product(s). Hydroboration–oxidation proceeds with syn addition, meaning that the hydrogen (H) and hydroxyl group (-OH) are added to the same face of the alkene. This stereochemical outcome must be considered when proposing the starting alkene.

Propose a potential alkene structure. The starting alkene should have a double bond positioned such that the anti-Markovnikov addition of water leads to the observed alcohol product(s) with the correct stereochemistry.

Verify the stereochemical relationship between the proposed alkene and the alcohol product(s). Ensure that the syn addition mechanism of hydroboration–oxidation aligns with the relative stereochemistry of the alcohol product(s).

Confirm that the proposed alkene is consistent with the reaction conditions and the exclusive formation of the given alcohol product(s). If necessary, adjust the structure of the alkene to ensure it matches the observed outcome.

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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 that converts alkenes into alcohols. In the first step, borane (BH₃) adds across the double bond of the alkene, resulting in a trialkylborane intermediate. The second step involves oxidation with hydrogen peroxide (H₂O₂) in a basic solution, which replaces the boron atom with a hydroxyl group, yielding an alcohol. This reaction is notable for its syn-addition mechanism, leading to specific stereochemical outcomes.

Stereochemistry

Stereochemistry refers to the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the context of hydroboration-oxidation, the reaction proceeds with syn-addition, meaning that the boron and hydrogen atoms add to the same side of the double bond. This results in a specific stereochemical configuration of the resulting alcohol, which is crucial for predicting the product's properties and reactivity.

Regioselectivity

Regioselectivity is the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In hydroboration-oxidation, the boron atom adds to the less substituted carbon of the alkene, leading to the formation of the more stable, less sterically hindered alcohol. Understanding regioselectivity is essential for predicting the outcome of the reaction and ensuring the desired alcohol is produced.

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