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

Diazo Replacement Reactions

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

Diazo Replacement Reactions

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2:07 minutes

Problem 25d,e

Textbook Question

Show how you would convert aniline to the following compounds.
(d) bromobenzene
(e) iodobenzene

Verified step by step guidance

Step 1: Begin with aniline (C₆H₅NH₂) as the starting material. The amino group (-NH₂) on the benzene ring is highly activating and ortho/para-directing, so it must first be converted into a less reactive group to prevent unwanted side reactions during halogenation.

Step 2: Protect the amino group by converting it into an acetamide group. This can be achieved by reacting aniline with acetic anhydride (CH₃CO)₂O to form acetanilide (C₆H₅NHCOCH₃). The acetamide group is less activating and still ortho/para-directing.

Step 3: Perform the halogenation reaction. For bromobenzene, treat acetanilide with bromine (Br₂) in the presence of a mild Lewis acid catalyst such as FeBr₃. This will result in bromination at the para position relative to the acetamide group, forming para-bromoacetanilide.

Step 4: For iodobenzene, treat acetanilide with iodine (I₂) in the presence of an oxidizing agent such as nitric acid (HNO₃) or potassium iodate (KIO₃). This will result in iodination at the para position relative to the acetamide group, forming para-iodoacetanilide.

Step 5: Finally, hydrolyze the acetamide group back to the amino group by treating the halogenated acetanilide with aqueous acid or base (e.g., HCl or NaOH). This will yield the desired halogenated benzene derivatives: bromobenzene (C₆H₅Br) and iodobenzene (C₆H₅I).

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Key Concepts

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

Electrophilic Aromatic Substitution

Electrophilic aromatic substitution (EAS) is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. Aniline, which contains an amino group (-NH2) that is a strong activating group, undergoes EAS readily. Understanding this mechanism is crucial for converting aniline to bromobenzene and iodobenzene, as it involves the introduction of halogens onto the aromatic ring.

Halogenation of Aromatic Compounds

Halogenation is a specific type of electrophilic aromatic substitution where halogens (like bromine or iodine) are introduced to an aromatic compound. In the case of converting aniline to bromobenzene or iodobenzene, the reaction typically requires a halogen source (Br2 or I2) and a catalyst (like FeBr3 or I2) to facilitate the substitution. The choice of halogen and conditions affects the reaction's selectivity and yield.

Deactivation of the Amino Group

While the amino group in aniline is a strong activating group for EAS, it can also lead to over-substitution or unwanted side reactions. To convert aniline to bromobenzene or iodobenzene, it may be necessary to temporarily deactivate the amino group, often by converting it to a less reactive form, such as an acetanilide. This step helps control the reaction conditions and ensures that only one halogen is introduced to the aromatic ring.

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