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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3:15 minutes

Problem 20f

Textbook Question

Show how you would use the Friedel–Crafts acylation, Clemmensen reduction, and/or Gatterman–Koch synthesis to prepare the following compounds:
f. 1-phenyl-2,2-dimethylpropane

Verified step by step guidance

Step 1: Begin with benzene as the starting material. To introduce the acyl group, use the Friedel–Crafts acylation reaction. React benzene with isobutyryl chloride (CH3C(O)CH(CH3)2) in the presence of a Lewis acid catalyst such as AlCl3. This will yield 1-phenyl-2-methylpropan-1-one (a ketone).

Step 2: The product from Step 1 contains a ketone group. To reduce the ketone to a methylene group (-CH2-), use the Clemmensen reduction. Treat the ketone with zinc amalgam (Zn(Hg)) and concentrated hydrochloric acid (HCl). This will convert the ketone into 1-phenyl-2,2-dimethylpropane.

Step 3: Verify the structure of the final product to ensure it matches 1-phenyl-2,2-dimethylpropane. The benzene ring should be attached to a carbon atom that is bonded to two methyl groups and one hydrogen atom.

Step 4: Consider any potential side reactions or limitations of the Friedel–Crafts acylation and Clemmensen reduction. For example, ensure that the starting materials and reagents are compatible and that the reaction conditions are controlled to avoid over-reduction or rearrangements.

Step 5: If needed, purify the final product using techniques such as distillation or recrystallization to isolate 1-phenyl-2,2-dimethylpropane in its pure form.

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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 aluminum chloride, to form a ketone. The acyl group enhances the reactivity of the aromatic ring, allowing for further functionalization, which is crucial for synthesizing complex organic molecules.

Clemmensen Reduction

The Clemmensen reduction is a chemical reaction that reduces carbonyl groups (aldehydes and ketones) to alkanes using zinc amalgam and hydrochloric acid. This method is particularly useful for converting acylated aromatic compounds into their corresponding alkylated derivatives, facilitating the synthesis of hydrocarbons like 1-phenyl-2,2-dimethylpropane from acylated precursors.

Gatterman–Koch Synthesis

The Gatterman–Koch synthesis is a method for synthesizing aromatic aldehydes through the formylation of aromatic compounds using carbon monoxide and hydrochloric acid in the presence of a Lewis acid catalyst. This reaction is significant for introducing functional groups into aromatic systems, which can be further manipulated to create complex structures, such as the desired alkane in the question.

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