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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3:06 minutes

Problem 63a

Textbook Question

Predict the product of the following benzylic bromination reactions.
(a)

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Identify the benzylic position in the given molecule. The benzylic position is the carbon atom directly attached to the benzene ring, which in this case is the carbon atom adjacent to the triple bond.

Understand that benzylic bromination typically involves the substitution of a hydrogen atom at the benzylic position with a bromine atom. This is due to the stability of the benzylic radical formed during the reaction.

Consider the reagents typically used for benzylic bromination, such as N-bromosuccinimide (NBS) in the presence of light or heat, which facilitates the formation of bromine radicals.

Predict the product by replacing the hydrogen atom at the benzylic position with a bromine atom. This involves breaking the C-H bond and forming a new C-Br bond at the benzylic position.

Ensure that the stereochemistry of the molecule is maintained, as benzylic bromination does not typically affect the stereochemistry of the rest of the molecule.

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Key Concepts

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

Benzylic Bromination

Benzylic bromination involves the selective substitution of a hydrogen atom at the benzylic position with a bromine atom, typically using N-bromosuccinimide (NBS) as the brominating agent. This reaction is favored due to the stability of the benzylic radical formed during the process, which is stabilized by resonance with the aromatic ring.

Radical Stability

Radical stability is crucial in benzylic bromination, as the reaction proceeds through a radical intermediate. Benzylic radicals are particularly stable due to resonance stabilization, where the unpaired electron can delocalize over the aromatic ring, reducing the energy of the radical and making the reaction more favorable.

Resonance

Resonance in organic chemistry refers to the delocalization of electrons across adjacent atoms, which can stabilize intermediates like radicals. In benzylic bromination, the benzylic radical benefits from resonance with the aromatic ring, allowing the electron density to be spread over multiple atoms, thus stabilizing the radical and facilitating the reaction.

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

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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.

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

(d)

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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

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?

Multiple Choice

Which of the following does NOT explain why reactive intermediates at the benzylic position are relatively stable?

Multiple Choice

Which of the following reagents will prepare the given target from the given starting material?

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