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:Retrosynthesis

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

EAS:Retrosynthesis

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2:52 minutes

Problem 31d

Textbook Question

Show how the following compounds can be synthesized from benzene:
d. m-methylnitrobenzene

Verified step by step guidance

Step 1: Begin with benzene as the starting material. Benzene is a simple aromatic compound with a planar, cyclic structure and alternating double bonds, making it highly stable and reactive in electrophilic aromatic substitution reactions.

Step 2: Introduce a nitro group (-NO₂) to the benzene ring through a nitration reaction. This is achieved by treating benzene with a mixture of concentrated sulfuric acid (H₂SO₄) and concentrated nitric acid (HNO₃). The reaction generates the nitronium ion (NO₂⁺), which acts as the electrophile. The product is nitrobenzene.

Step 3: Introduce a methyl group (-CH₃) to the meta position relative to the nitro group. Since the nitro group is a meta-directing group due to its electron-withdrawing nature, a Friedel-Crafts alkylation reaction can be used. Treat nitrobenzene with methyl chloride (CH₃Cl) in the presence of a Lewis acid catalyst, such as aluminum chloride (AlCl₃). This will result in the formation of m-methylnitrobenzene.

Step 4: Carefully control the reaction conditions to avoid over-alkylation or side reactions. Ensure that the methyl group is added only once and that the meta position is favored due to the directing effects of the nitro group.

Step 5: Purify the product, m-methylnitrobenzene, using appropriate techniques such as recrystallization or distillation to ensure the desired compound is isolated in high purity.

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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 synthesizing various substituted aromatic compounds, including nitro and alkyl derivatives. Understanding EAS mechanisms, such as the role of the electrophile and the stability of the intermediates, is essential for predicting the products formed from benzene.

Nitration of Aromatic Compounds

Nitration is a specific type of electrophilic aromatic substitution where a nitro group (-NO2) is introduced into an aromatic ring. This reaction typically involves the use of a nitrating mixture, such as concentrated nitric acid and sulfuric acid, to generate the nitronium ion (NO2+), the active electrophile. Recognizing the conditions and regioselectivity of nitration is vital for synthesizing compounds like m-methylnitrobenzene from benzene.

Regioselectivity in Substitution Reactions

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the case of m-methylnitrobenzene synthesis, understanding how the existing methyl group influences the position where the nitro group is added is crucial. The methyl group is an ortho/para-directing group, but due to steric hindrance, the nitro group will preferentially attach at the meta position in this specific synthesis.

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