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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6:00 minutes

Problem 81

Textbook Question

Describe how naphthalene can be prepared from the given starting material.

Verified step by step guidance

Step 1: Analyze the starting material. The given compound is phenylpropionyl chloride, which contains a benzene ring attached to a three-carbon chain ending in an acyl chloride functional group (C=O-Cl). This structure suggests that the reaction will involve cyclization and aromatic stabilization.

Step 2: Recognize the target molecule. Naphthalene is a polycyclic aromatic hydrocarbon consisting of two fused benzene rings. The synthesis will require forming a second aromatic ring through cyclization and elimination reactions.

Step 3: Propose the reaction mechanism. The synthesis of naphthalene from phenylpropionyl chloride typically involves a Friedel-Crafts acylation reaction followed by cyclization. A Lewis acid catalyst, such as AlCl₃, is used to activate the acyl chloride group, facilitating the formation of an electrophilic intermediate.

Step 4: Describe the cyclization process. After the acylation step, the intermediate undergoes intramolecular cyclization. This step involves the formation of a new carbon-carbon bond between the benzene ring and the terminal carbon of the three-carbon chain, leading to the formation of a second aromatic ring.

Step 5: Finalize the reaction. The cyclized intermediate undergoes dehydrogenation to form naphthalene. This step ensures the aromaticity of both rings in the final product. Common reagents for dehydrogenation include Pd/C or other catalysts under high-temperature conditions.

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Key Concepts

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

Naphthalene Structure and Properties

Naphthalene is a polycyclic aromatic hydrocarbon consisting of two fused benzene rings. Its structure contributes to its stability and unique properties, such as its volatility and ability to undergo electrophilic substitution reactions. Understanding its molecular structure is essential for predicting its reactivity and the types of reactions that can be used to synthesize it.

Electrophilic Aromatic Substitution (EAS)

Electrophilic aromatic substitution is a fundamental reaction mechanism in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. This process is crucial for synthesizing compounds like naphthalene from simpler aromatic precursors. Familiarity with EAS helps in understanding how to manipulate starting materials to achieve desired products.

Synthetic Pathways for Naphthalene

There are several synthetic pathways to prepare naphthalene, including the fusion of two benzene rings or the cyclization of certain precursors. Common methods include the reduction of 1,4-dihalobenzenes or the dehydrogenation of alkylnaphthalenes. Knowing these pathways allows chemists to choose the most efficient route based on the available starting materials.

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