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

Nucleophilic Aromatic Substitution

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

Nucleophilic Aromatic Substitution

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5:24 minutes

Problem 64b

Textbook Question

Show how the substituents containing the azo group (N=N) can facilitate both electrophilic and nucleophilic aromatic substitution.
(b)

Verified step by step guidance

Step 1: Understand the role of the azo group (N=N) in aromatic substitution. The azo group is an electron-withdrawing group due to the resonance and inductive effects of the nitrogen atoms. This influences the reactivity of the aromatic ring in both electrophilic and nucleophilic aromatic substitution reactions.

Step 2: For electrophilic aromatic substitution, the azo group deactivates the aromatic ring by withdrawing electron density. This makes the ring less reactive toward electrophiles. However, the azo group can direct substitution to specific positions (meta-directing) due to its electron-withdrawing nature.

Step 3: For nucleophilic aromatic substitution, the electron-withdrawing nature of the azo group increases the susceptibility of the aromatic ring to attack by nucleophiles. This is particularly effective when there are additional electron-withdrawing groups (e.g., fluorine) on the ring, which stabilize the intermediate formed during the substitution process.

Step 4: Analyze the reaction provided in the image. The fluorine atom on the aromatic ring is an electron-withdrawing group, and the azo group further enhances the ring's susceptibility to nucleophilic attack. The diethylamine (Et2NH) acts as a nucleophile, replacing the fluorine atom via nucleophilic aromatic substitution.

Step 5: The product shows the diethylamino group (Et2N) attached to the aromatic ring, indicating successful nucleophilic substitution. The azo group remains intact, and the tert-butyl carbamate group (O-t-Bu) is unaffected, serving as a protecting group for the azo functionality.

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Key Concepts

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

Azo Group

The azo group (N=N) is a functional group characterized by a nitrogen-nitrogen double bond. It is commonly found in azo compounds, which are often brightly colored and used in dyes. The presence of the azo group can significantly influence the reactivity of aromatic compounds, making them more susceptible to both electrophilic and nucleophilic substitution reactions due to the resonance stabilization it provides.

Electrophilic Aromatic Substitution (EAS)

Electrophilic aromatic substitution is a fundamental reaction in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. The presence of electron-donating groups, such as those attached to an azo group, can enhance the electron density of the aromatic system, making it more reactive towards electrophiles. This process is crucial for synthesizing various aromatic compounds and understanding the reactivity patterns of substituted aromatics.

Nucleophilic Aromatic Substitution (NAS)

Nucleophilic aromatic substitution occurs when a nucleophile attacks an aromatic ring, typically at a carbon atom that is bonded to a leaving group. The presence of electron-withdrawing groups, such as the azo group, can stabilize the negative charge developed during the reaction, facilitating the substitution process. This reaction is particularly important in the synthesis of complex organic molecules and in understanding the behavior of aromatic systems under different conditions.

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