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

Halohydrin

Organic Chemistry

10. Addition Reactions

Halohydrin

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8:59 minutes

Problem 79

Textbook Question

Which stereoisomer of 3-hexene forms (3S,4S)-4-bromo-3-hexanol and (3R,4R)-4-bromo-3-hexanol when it reacts with Br₂ and H₂O?

Verified step by step guidance

Identify the structure of 3-hexene. It is a six-carbon alkene with a double bond between carbons 3 and 4. The stereoisomers of 3-hexene are the cis (Z) and trans (E) forms. These differ in the spatial arrangement of the substituents around the double bond.

Understand the reaction mechanism. When 3-hexene reacts with Br2 and H2O, it undergoes a halohydrin formation reaction. In this reaction, the bromine molecule (Br2) adds across the double bond, and water acts as a nucleophile to form a bromohydrin.

Analyze the stereochemical outcome. The addition of Br2 to the double bond occurs via an anti-addition mechanism, meaning the bromine and hydroxyl groups will add to opposite faces of the double bond. This anti-addition leads to the formation of enantiomers.

Determine which stereoisomer of 3-hexene leads to the specified products. The (3S,4S)-4-bromo-3-hexanol and (3R,4R)-4-bromo-3-hexanol are enantiomers, which means they are formed from the cis (Z) isomer of 3-hexene. The cis isomer allows for the anti-addition to produce these specific stereochemical configurations.

Conclude that the cis (Z) stereoisomer of 3-hexene is the one that forms (3S,4S)-4-bromo-3-hexanol and (3R,4R)-4-bromo-3-hexanol when it reacts with Br2 and H2O.

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Key Concepts

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

Stereoisomerism

Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. This can lead to different physical and chemical properties. In the case of alkenes like 3-hexene, stereoisomers can exist as cis or trans forms, which are crucial for determining the outcome of reactions involving stereospecificity.

Electrophilic Addition Reactions

Electrophilic addition reactions are a type of reaction where an electrophile reacts with a nucleophile, typically involving alkenes. In the context of 3-hexene reacting with Br2 and H2O, the double bond acts as a nucleophile, attacking the electrophilic bromine, leading to the formation of bromohydrins. Understanding this mechanism is essential for predicting the stereochemical outcomes of the reaction.

Stereochemistry of Reaction Products

Stereochemistry involves the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the reaction of 3-hexene with Br2 and H2O, the stereochemistry of the resulting products, (3S,4S)-4-bromo-3-hexanol and (3R,4R)-4-bromo-3-hexanol, is determined by the mechanism of the addition reaction and the configuration of the starting alkene. This concept is vital for predicting which stereoisomer will be formed.

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