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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4:41 minutes

Problem 71

Textbook Question

Benzene underwent a Friedel–Crafts acylation followed by a Wolff–Kishner reduction. The product gave the following 1H NMR spectrum. What acyl chloride was used in the Friedel–Crafts acylation?
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Verified step by step guidance

Analyze the Friedel–Crafts acylation reaction: In this reaction, benzene reacts with an acyl chloride (RCOCl) in the presence of a Lewis acid catalyst (e.g., AlCl₃) to form an aromatic ketone. The acyl group (RCO-) is introduced onto the benzene ring.

Understand the Wolff–Kishner reduction: This reaction reduces a ketone (C=O) to a methylene group (-CH₂-) using hydrazine (N₂H₄) and a strong base (e.g., KOH) under heat. The ketone formed in the Friedel–Crafts acylation will be reduced to an alkyl group.

Interpret the 1H NMR spectrum: Examine the chemical shifts, splitting patterns, and integration values in the spectrum. These features will help identify the structure of the final product and, by extension, the acyl group introduced in the Friedel–Crafts acylation.

Work backward from the final product: Based on the NMR data, determine the structure of the alkyl group attached to the benzene ring after the Wolff–Kishner reduction. This alkyl group corresponds to the R group in the original acyl chloride (RCOCl).

Identify the acyl chloride: Use the structure of the alkyl group deduced from the NMR spectrum to determine the corresponding acyl chloride (RCOCl) that was used in the Friedel–Crafts acylation.

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Key Concepts

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

Friedel–Crafts Acylation

Friedel–Crafts acylation is an electrophilic aromatic substitution reaction where an acyl group is introduced into an aromatic ring using an acyl chloride and a Lewis acid catalyst. This reaction allows for the formation of ketones on the aromatic compound, which can significantly alter its reactivity and properties. Understanding the mechanism and the role of the catalyst is crucial for predicting the product structure.

Wolff–Kishner Reduction

The Wolff–Kishner reduction is a chemical reaction that reduces carbonyl compounds, such as ketones and aldehydes, to alkanes using hydrazine and a strong base, typically potassium hydroxide. This reaction is important in organic synthesis for removing functional groups while preserving the carbon skeleton. Recognizing how this reduction affects the structure of the product is essential for interpreting the final outcome of the reaction sequence.

1H NMR Spectroscopy

Proton nuclear magnetic resonance (1H NMR) spectroscopy is a powerful analytical technique used to determine the structure of organic compounds by analyzing the magnetic environment of hydrogen atoms in a molecule. The chemical shifts, splitting patterns, and integration of peaks provide insights into the molecular structure, including the presence of functional groups and the connectivity of atoms. Interpreting the 1H NMR spectrum is key to identifying the acyl chloride used in the acylation step.

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