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:Friedel-Crafts Acylation Mechanism

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

EAS:Friedel-Crafts Acylation Mechanism

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5:30 minutes

Problem 50k,l

Textbook Question

Predict the major products formed when benzene reacts (just once) with the following reagents.
(k) carbon monoxide, HCl, and AlCl₃/CuCl
(l) CH₂(COCl)₂, AlCl₃

Verified step by step guidance

Step 1: Recognize the type of reaction involved. Both reactions involve electrophilic aromatic substitution (EAS), where benzene reacts with an electrophile to form a substituted benzene derivative.

Step 2: For reaction (k), identify the reagents: carbon monoxide (CO), HCl, and AlCl3/CuCl. This combination is used in the Gattermann-Koch reaction, which introduces a formyl group (-CHO) onto the benzene ring. The electrophile generated in this reaction is the formyl cation (HCO⁺).

Step 3: In the Gattermann-Koch reaction, the formyl cation (HCO⁺) is generated by the reaction of CO and HCl in the presence of AlCl3 and CuCl. This electrophile then reacts with benzene to form benzaldehyde (C6H5CHO) as the major product.

Step 4: For reaction (l), identify the reagents: CH2(COCl)2 and AlCl3. This combination is used in a Friedel-Crafts acylation reaction. The reagent CH2(COCl)2 is malonyl chloride, and in the presence of AlCl3, it generates an acylium ion (CH(CO)⁺) as the electrophile.

Step 5: In the Friedel-Crafts acylation reaction, the acylium ion (CH(CO)⁺) reacts with benzene to form a substituted benzene derivative. The major product is benzene with a CH(CO) group attached, specifically phenylacetyl chloride (C6H5CH(CO)Cl).

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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 mechanism in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring. This process is crucial for understanding how benzene and its derivatives react with various reagents, leading to the formation of substituted aromatic compounds. The stability of the aromatic system is maintained during the reaction, making EAS a key concept in predicting the products of reactions involving benzene.

Friedel-Crafts Acylation

Friedel-Crafts acylation is a specific type of electrophilic aromatic substitution that introduces an acyl group into an aromatic ring. This reaction typically involves the use of an acyl chloride and a Lewis acid catalyst, such as AlCl3, to generate the acylium ion, which acts as the electrophile. Understanding this mechanism is essential for predicting the products when benzene reacts with acylating agents like CH2(COCl)2.

Reactivity of Electrophiles

The reactivity of electrophiles is a critical concept in organic chemistry, as it determines how readily a given electrophile will react with an aromatic compound. Factors such as the electrophile's charge, size, and the presence of electron-withdrawing or donating groups influence its strength and ability to attack the electron-rich aromatic ring. In the context of the question, understanding the nature of the electrophiles generated from the reagents is vital for predicting the major products formed in the reactions.

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