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

19. Reactions of Aromatics: EAS and Beyond

Side-Chain Halogenation

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

Side-Chain Halogenation

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4:05 minutes

Problem 58d

Textbook Question

Show the products you expect when each compound reacts with NBS with light shining on the reaction.
(d)

Verified step by step guidance

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

Step 2: Identify the benzylic position in the given compound. The structure contains a benzene ring attached to a propyl group. The benzylic position is the carbon atom directly attached to the benzene ring in the propyl chain.

Step 3: Determine the radical intermediate. Under light, the reaction proceeds via a radical mechanism. The benzylic hydrogen is abstracted to form a benzylic radical, which is stabilized due to resonance with the benzene ring.

Step 4: Add bromine to the benzylic radical. The bromine atom from NBS reacts with the benzylic radical to form the brominated product. The bromine is added at the benzylic position.

Step 5: Verify the product structure. The final product will have a bromine atom attached to the benzylic position, replacing one of the hydrogens. The rest of the molecule remains unchanged.

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Key Concepts

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

NBS (N-Bromosuccinimide)

NBS is a reagent commonly used in organic chemistry for bromination reactions, particularly in the presence of light. It generates bromine radicals under photolytic conditions, which can abstract hydrogen atoms from alkenes or alkanes, leading to the formation of brominated products. Understanding how NBS functions is crucial for predicting the products of reactions involving this compound.

Radical Mechanism

The radical mechanism involves the formation and reaction of free radicals, which are highly reactive species with unpaired electrons. In the context of NBS reactions, light initiates the homolytic cleavage of the N-Br bond, generating bromine radicals that can abstract hydrogen from the substrate. This mechanism is essential for understanding how products are formed in radical bromination reactions.

Substitution vs. Addition Reactions

In organic chemistry, substitution reactions involve replacing one atom or group in a molecule with another, while addition reactions involve adding atoms or groups to a molecule. When reacting with NBS, the process typically leads to substitution of hydrogen atoms with bromine, particularly at allylic positions. Recognizing the type of reaction occurring helps in predicting the structure of the final products.

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Related Practice

Textbook Question

Suggest reagents and reaction conditions that would result in synthesis of the following bromoalkanes.

(c)

Textbook Question

Predict the product of the following benzylic bromination reactions.

(c)

Textbook Question

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

Textbook Question

Show how you would convert (in one or two steps) 1-phenylpropane to the three products shown below. In each case, explain what unwanted reactions might produce undesirable impurities in the product.

Textbook Question

Predict the major products of treating the following compounds with hot, concentrated potassium permanganate, followed by acidification with dilute HCl.

(a) isopropylbenzene

(b) p-xylene

(c)

Textbook Question

Predict the product of the following benzylic bromination reactions.

(a)

Textbook Question

A radical reaction, as it progressed through its propagation steps, involved the following radical species. Suggest which products might form in all possible termination steps (six products are possible).

Multiple Choice

Which position in the following molecule is the benzylic position?

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Show the products you expect when each compound reacts with NBS with light shining on the reaction.(d)

Key Concepts

NBS (N-Bromosuccinimide)

Radical Mechanism

Substitution vs. Addition Reactions

Watch next

Show the products you expect when each compound reacts with NBS with light shining on the reaction.
(d)