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:Sequence Groups

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

EAS:Sequence Groups

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4:40 minutes

Problem 20a

Textbook Question

Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:
a.

Verified step by step guidance

Step 1: Begin with Friedel–Crafts acylation to introduce the acyl group onto the benzene ring. Use benzene as the starting material and react it with isobutyryl chloride (CH3CH(CH3)COCl) in the presence of a Lewis acid catalyst such as AlCl3. This will yield isobutyl phenyl ketone (Ph-C=O-CH2CH(CH3)2).

Step 2: Perform a Clemmensen reduction to convert the ketone group into a methylene group. React the isobutyl phenyl ketone with zinc amalgam (Zn(Hg)) and concentrated hydrochloric acid (HCl). This will reduce the carbonyl group to a CH2 group, forming isobutylbenzene.

Step 3: Verify the structure of the final product, isobutylbenzene, to ensure the correct substitution pattern on the benzene ring. The structure should have a benzene ring attached to a CH2 group, which is further connected to CH(CH3)2.

Step 4: If using Gatterman–Koch synthesis, note that this method is typically used for introducing a formyl group (-CHO) onto the benzene ring. It is not directly applicable for synthesizing isobutylbenzene but could be used in a different synthetic route if needed.

Step 5: Ensure all reagents and conditions are appropriate for each step, and confirm the reaction mechanisms align with the desired transformations. Friedel–Crafts acylation and Clemmensen reduction are the most direct methods for this synthesis.

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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 that introduces an acyl group into an aromatic ring. This reaction typically uses an acyl chloride and a Lewis acid catalyst, such as AlCl3, to form a ketone. The resulting acylated aromatic compound can serve as a precursor for further transformations, making it essential for synthesizing complex organic molecules.

Clemmensen Reduction

The Clemmensen reduction is a chemical reaction that reduces carbonyl groups (ketones or aldehydes) to alkanes using zinc amalgam and hydrochloric acid. This method is particularly useful for converting acylated aromatic compounds into their corresponding alkylated derivatives, allowing for the removal of the carbonyl functionality while preserving the aromatic system.

Gatterman–Koch Synthesis

The Gatterman–Koch synthesis is a method for synthesizing aromatic aldehydes from aromatic compounds using carbon monoxide and hydrochloric acid in the presence of a Lewis acid catalyst. This reaction is significant for introducing carbonyl functionalities into aromatic systems, which can then be further manipulated in organic synthesis, such as in the preparation of ketones or other derivatives.

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