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

EAS:Synergistic and Competitive Groups

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

EAS:Synergistic and Competitive Groups

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4:24 minutes

Problem 58a,b

Textbook Question

For each of the following compounds, indicate the ring carbon(s) that is/are nitrated when the compound is treated with HNO₃/H₂SO₄:
a.
b.

Verified step by step guidance

Step 1: Analyze the substituents on the benzene ring for each compound. Substituents influence the reactivity and regioselectivity of electrophilic aromatic substitution reactions, such as nitration. Electron-withdrawing groups (e.g., NO2, COOH) are deactivating and direct incoming groups to meta positions, while electron-donating groups (e.g., alkoxy groups) are activating and direct to ortho/para positions.

Step 2: For compound (a), the benzene ring has two substituents: a nitro group (-NO2) and a carboxylic acid group (-COOH). Both are electron-withdrawing and deactivating, directing incoming electrophiles to the meta positions relative to themselves. Identify the meta positions relative to each substituent and determine overlap.

Step 3: For compound (b), the benzene ring has two ester groups (-COOCH3). Ester groups are electron-withdrawing through resonance and inductive effects, but they are less deactivating compared to nitro groups. They direct incoming electrophiles to the meta positions relative to themselves. Identify the meta positions relative to each ester group and determine overlap.

Step 4: Consider steric hindrance in both compounds. In compound (a), the nitro and carboxylic acid groups may create steric hindrance at certain positions, potentially affecting the likelihood of nitration at those sites. Similarly, in compound (b), the ester groups may influence steric accessibility of the meta positions.

Step 5: Summarize the positions on the benzene ring for each compound that are most likely to undergo nitration based on the electronic and steric effects of the substituents. These positions are determined by the directing effects of the substituents and the overlap of meta positions.

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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. This process is crucial for understanding how substituents influence the reactivity of aromatic compounds. In the context of nitration, the electrophile is the nitronium ion (NO2+), generated from nitric acid and sulfuric acid, which attacks the electron-rich aromatic ring.

Directing Effects of Substituents

Substituents on an aromatic ring can either be electron-donating or electron-withdrawing, affecting the position where new substituents are added during EAS. Electron-donating groups (like -OH or -OCH3) direct incoming electrophiles to the ortho and para positions, while electron-withdrawing groups (like -NO2 or -CF3) direct them to the meta position. Understanding these directing effects is essential for predicting the outcome of nitration reactions.

Nitration Mechanism

The nitration mechanism involves the generation of the nitronium ion, which acts as the electrophile in the reaction. The mechanism proceeds through the formation of a sigma complex (arenium ion) after the electrophile attacks the aromatic ring, followed by deprotonation to restore aromaticity. Recognizing this mechanism helps in identifying which carbon atoms in the ring will be nitrated based on the existing substituents.

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