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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5:04 minutes

Problem 40c

Textbook Question

Show how each of the following compounds can be synthesized from benzene:
c. p-bromoanisole

Verified step by step guidance

Step 1: Begin with benzene as the starting material. Benzene is a simple aromatic compound that serves as the foundation for the synthesis.

Step 2: Introduce a bromine substituent to the benzene ring by performing an electrophilic aromatic substitution (EAS) reaction. Use bromine (Br₂) and a Lewis acid catalyst such as FeBr₃ to brominate benzene, forming bromobenzene. The reaction mechanism involves the formation of a bromonium ion intermediate.

Step 3: Protect the para position for the next substitution. To achieve the desired para orientation, introduce a methoxy group (-OCH₃) to the benzene ring. This can be done by reacting bromobenzene with sodium methoxide (NaOCH₃) in the presence of a suitable solvent like methanol. The methoxy group is an electron-donating group and directs further substitution to the para position.

Step 4: Ensure that the bromine and methoxy groups are in the correct para relationship. If the reaction conditions are controlled properly, the methoxy group will be introduced at the para position relative to the bromine substituent, yielding p-bromoanisole.

Step 5: Purify the product using techniques such as recrystallization or column chromatography to isolate p-bromoanisole. Confirm the structure of the compound using spectroscopic methods like NMR or IR to verify the presence of the bromine and methoxy groups in the para 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 synthesizing various aromatic compounds, including p-bromoanisole from benzene. Understanding the mechanism of EAS, including the role of catalysts and the stability of intermediates, is essential for predicting the outcomes of such reactions.

Bromination of Aromatic Compounds

Bromination is a specific type of electrophilic aromatic substitution where bromine is introduced into an aromatic compound. In the synthesis of p-bromoanisole, bromine can be added to the benzene ring after it has been activated by a methoxy group (from anisole). This step is critical as it determines the position of the bromine substitution, which in this case is para to the methoxy group due to its electron-donating properties.

Methoxy Group as a Director

The methoxy group (-OCH3) is an electron-donating substituent that influences the reactivity and orientation of electrophilic substitution on the aromatic ring. It directs incoming electrophiles to the ortho and para positions relative to itself. In the synthesis of p-bromoanisole, the methoxy group enhances the electron density of the benzene ring, facilitating the bromination at the para position, which is a key aspect of the synthesis process.