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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3:18 minutes

Problem 19c

Textbook Question

Show how you would synthesize the following aromatic derivatives from benzene.
c. p-chlorotoluene

Verified step by step guidance

Step 1: Begin with benzene as the starting material. Benzene is an aromatic compound with a six-membered ring and alternating double bonds.

Step 2: Introduce a methyl group onto the benzene ring to form toluene. This can be achieved through a Friedel-Crafts alkylation reaction using methyl chloride (CH₃Cl) and a Lewis acid catalyst such as aluminum chloride (AlCl₃). The reaction proceeds via electrophilic aromatic substitution.

Step 3: Once toluene is formed, introduce a chlorine atom at the para position relative to the methyl group. This can be done through an electrophilic aromatic substitution reaction using chlorine gas (Cl₂) and a catalyst such as ferric chloride (FeCl₃). The methyl group is an electron-donating group, which directs the incoming chlorine to the para position due to its activating and ortho/para-directing effects.

Step 4: Carefully control the reaction conditions to ensure selective chlorination at the para position. This may involve using a stoichiometric amount of chlorine and monitoring the reaction to avoid over-chlorination.

Step 5: Purify the product, p-chlorotoluene, using techniques such as distillation or recrystallization to remove any unreacted starting materials or side products.

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Key Concepts

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

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. This process is crucial for synthesizing various aromatic compounds, including derivatives of benzene. The reaction typically involves the generation of a highly reactive electrophile, which then attacks the electron-rich aromatic system, leading to the formation of a substituted product.

Activating and Deactivating Groups

In the context of EAS, substituents on the aromatic ring can either activate or deactivate the ring towards further substitution. Activating groups, such as alkyl groups, increase the electron density of the ring, making it more reactive, while deactivating groups, like halogens, reduce reactivity. Understanding the influence of these groups is essential for predicting the position of new substituents in the synthesis of compounds like p-chlorotoluene.

Halogenation of Aromatic Compounds

Halogenation is a specific type of EAS where a halogen atom is introduced into an aromatic compound. In the case of synthesizing p-chlorotoluene, the process involves the chlorination of toluene, which is already an aromatic compound with a methyl group. The presence of the methyl group directs the incoming chlorine to the para position, resulting in the formation of p-chlorotoluene, demonstrating the regioselectivity of EAS reactions.

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