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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6:42 minutes

Problem 61

Textbook Question

Describe two ways to prepare anisole from benzene.

Verified step by step guidance

Step 1: **Preparation via Friedel-Crafts Alkylation and Williamson Ether Synthesis**: Start with benzene. Perform a Friedel-Crafts alkylation reaction by reacting benzene with methyl chloride (CH₃Cl) in the presence of a Lewis acid catalyst like AlCl₃. This will yield toluene (methylbenzene). Next, oxidize the methyl group of toluene to a phenol group using an oxidizing agent like KMnO₄. Finally, perform a Williamson Ether Synthesis by reacting phenol with methyl iodide (CH₃I) in the presence of a strong base like NaOH to form anisole (methoxybenzene).

Step 2: **Preparation via Phenol Methylation**: Start with benzene and perform a nitration reaction by reacting benzene with a mixture of concentrated HNO₃ and H₂SO₄ to form nitrobenzene. Reduce nitrobenzene to aniline (aminobenzene) using a reducing agent like Sn/HCl. Convert aniline to phenol by diazotization (using NaNO₂ and HCl at 0-5°C) followed by hydrolysis. Finally, methylate phenol by reacting it with dimethyl sulfate ((CH₃O)₂SO₂) or methyl iodide (CH₃I) in the presence of a base like NaOH to form anisole.

Step 3: **Key Reaction Mechanisms**: In the Friedel-Crafts alkylation, the Lewis acid catalyst (AlCl₃) generates a highly reactive electrophile (CH₃⁺) that reacts with benzene to form toluene. In the Williamson Ether Synthesis, the phenoxide ion (generated by deprotonating phenol with NaOH) acts as a nucleophile and attacks the methyl iodide (CH₃I) to form anisole.

Step 4: **Alternative Reagents and Conditions**: For the phenol methylation step, dimethyl sulfate ((CH₃O)₂SO₂) can also be used as a methylating agent instead of methyl iodide. Additionally, other oxidizing agents like CrO₃ or PCC can be used to oxidize toluene to phenol.

Step 5: **Safety and Environmental Considerations**: Ensure proper handling of reagents like AlCl₃, H₂SO₄, and dimethyl sulfate, as they are highly reactive and hazardous. Use appropriate safety equipment and dispose of waste according to environmental regulations.

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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. In the case of preparing anisole from benzene, EAS can occur through the introduction of a methoxy group (-OCH3) via the reaction of benzene with an electrophile such as methyl iodide in the presence of a strong base, which generates the necessary electrophile.

Friedel-Crafts Alkylation

Friedel-Crafts alkylation is a specific type of electrophilic aromatic substitution that involves the addition of an alkyl group to an aromatic ring. To prepare anisole, benzene can react with an alkyl halide (like methyl chloride) in the presence of a Lewis acid catalyst (such as AlCl3), which facilitates the formation of the alkyl cation that subsequently attaches to the benzene ring, forming an alkylated product that can be further converted to anisole.

Methoxy Group Introduction

The methoxy group (-OCH3) is a common functional group in organic chemistry that can be introduced into aromatic compounds through various methods. In the context of preparing anisole, the methoxy group can be introduced via the reaction of benzene with dimethyl sulfate or methyl iodide in the presence of a base, leading to the formation of anisole. Understanding the reactivity and stability of the methoxy group is crucial for predicting the outcomes of these reactions.

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