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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4:43 minutes

Problem 65c

Textbook Question

Identify A through O:

Verified step by step guidance

Step 1: Analyze the starting material. The given compound is an alkene with a double bond between the second and third carbon atoms in a chain. The structure also includes a methyl group attached to the second carbon.

Step 2: Recognize the reaction type. The reagents R₂BH/THF followed by HO⁻, H₂O₂, and H₂O indicate a hydroboration-oxidation reaction. This reaction converts an alkene into an alcohol.

Step 3: Understand the regioselectivity of hydroboration. Hydroboration-oxidation follows anti-Markovnikov addition, meaning the hydroxyl group (-OH) will attach to the less substituted carbon of the double bond.

Step 4: Predict the intermediate. In the first step, the boron reagent (R₂BH) adds to the less substituted carbon of the double bond, forming an organoborane intermediate.

Step 5: Describe the final product. In the second step, oxidation with H₂O₂ and HO⁻ replaces the boron atom with a hydroxyl group (-OH), resulting in the formation of an alcohol at the less substituted carbon of the original double bond.

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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 into alcohols. The first step involves the addition of borane (BH3) to the alkene, forming an organoborane intermediate. In the second step, this intermediate is oxidized using hydrogen peroxide (H2O2) and hydroxide ions (OH-), resulting in the formation of an alcohol with anti-Markovnikov selectivity.

Anti-Markovnikov Addition

Anti-Markovnikov addition refers to the regioselectivity observed in certain reactions, where the less substituted carbon of an alkene receives the new substituent. In the context of hydroboration, this means that the boron atom attaches to the less substituted carbon, leading to the formation of an alcohol at that position after oxidation, which is contrary to the typical Markovnikov rule.

Reagents and Solvents

The choice of reagents and solvents is crucial in organic reactions. In hydroboration, R2BH (dialkylborane) is used as the boron source, and THF (tetrahydrofuran) serves as a solvent that stabilizes the reaction intermediates. The subsequent oxidation step employs HO-, H2O2, and H2O, which are essential for converting the organoborane into the corresponding alcohol, highlighting the importance of solvent and reagent compatibility in reaction mechanisms.

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Related Practice

Textbook Question

Suggest a reagent to carry out each of the following conversions to an alcohol.

(d)

Textbook Question

Predict the product(s) that would result when the following molecules are allowed to react under the following conditions: (i) 1. BH₃ 2. NaOH, H₂O₂ (ii) 1. Hg(OAc)₂ 2. NaBH₄ (iii) H₂SO₄ , H₂O (iv) 1. OsO₄ 2. NaHSO₃ (v) H₂O (vi) NaOH, H₂O . If there is no reaction, write 'no reaction.'

(d)

Textbook Question

Predict the product(s) that would result when the following molecules are allowed to react under the following conditions: (i) 1. BH₃ 2. NaOH, H₂O₂. If there is no reaction, write 'no reaction.'

(a)

Textbook Question

a. Show the reagents required to form the primary alcohol in each of the following reactions.

Textbook Question

Hydroboration, an electrophilic addition reaction like those studied in Section 21.4, only gives 1,2-addition to buta-1,3-diene, regardless of temperature. Why?

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.

(c)

Textbook Question

Would you expect the following to produce an equal or unequal mixture of stereoisomers?

(c)

Textbook Question

(b)

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