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

11. Radical Reactions

Allylic Bromination

Organic Chemistry

11. Radical Reactions

Allylic Bromination

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5:48 minutes

Problem 31d

Textbook Question

What is the major product of the following reactions? Disregard stereoisomers:
d.

Verified step by step guidance

Step 1: Recognize the reagent and reaction conditions. NBS (N-Bromosuccinimide) in the presence of heat (Δ) and peroxide is used for allylic bromination. This reaction selectively replaces a hydrogen atom at the allylic position with a bromine atom.

Step 2: Identify the allylic positions in the given molecule. The molecule is a substituted cyclohexene with two methyl groups. The allylic positions are the carbon atoms adjacent to the double bond.

Step 3: Determine the most reactive allylic position. The allylic position with the most stable radical intermediate will be favored. In this case, the allylic position adjacent to the methyl group is more stable due to hyperconjugation and inductive effects.

Step 4: Predict the major product. Bromine will replace the hydrogen atom at the most reactive allylic position, resulting in the formation of an allylic bromide.

Step 5: Disregard stereoisomers as instructed. The major product will be the allylic bromide formed at the most stable allylic position, without considering stereochemistry.

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Key Concepts

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

Allylic Bromination

Allylic bromination is a reaction where bromine is introduced at the allylic position of an alkene or alkane. This process typically involves the use of N-bromosuccinimide (NBS) in the presence of a radical initiator, such as peroxide, under heat. The reaction proceeds via a radical mechanism, where the allylic hydrogen is abstracted, forming a resonance-stabilized radical that can then react with bromine.

Radical Mechanism

A radical mechanism involves the formation and reaction of free radicals, which are highly reactive species with unpaired electrons. In the context of allylic bromination, the reaction begins with the generation of radicals through the homolytic cleavage of the N–Br bond in NBS, followed by the abstraction of hydrogen from the allylic position. This mechanism is crucial for understanding how the product distribution is influenced by the stability of the resulting radicals.

Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In allylic bromination, the stability of the radical intermediates determines the major product. More stable radicals, such as those formed at more substituted allylic positions, are favored, leading to a specific major product in the reaction. Understanding regioselectivity is essential for predicting the outcome of the reaction.

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What is the major product of the following reactions? Disregard stereoisomers: d.

Key Concepts

Allylic Bromination

Radical Mechanism

Regioselectivity

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What is the major product of the following reactions? Disregard stereoisomers:
d.