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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3:01 minutes

Problem 65g

Textbook Question

Show how the following compounds can be synthesized from benzene:
g. p-dideuteriobenzene

Verified step by step guidance

Step 1: Begin with benzene (C₆H₆) as the starting material. Benzene is a simple aromatic compound with a six-membered ring and alternating double bonds.

Step 2: To introduce deuterium (D) into the benzene ring, perform a deuterium exchange reaction. Treat benzene with deuterium gas (D₂) in the presence of a catalyst such as a platinum or palladium catalyst. This will replace all the hydrogen atoms in benzene with deuterium, forming perdeuterobenzene (C₆D₆).

Step 3: To selectively introduce deuterium at the para positions, first perform a Friedel-Crafts alkylation or acylation to introduce a directing group. For example, react benzene with an alkyl halide (e.g., CH₃Cl) or an acyl halide (e.g., CH₃COCl) in the presence of a Lewis acid catalyst (e.g., AlCl₃). This will introduce a substituent (e.g., CH₃ or COCH₃) at one position on the benzene ring.

Step 4: Use the substituent introduced in Step 3 as a directing group to guide the placement of deuterium. Treat the substituted benzene with D₂O (deuterium oxide) and a strong acid or base to exchange the hydrogen atoms at the ortho and para positions relative to the substituent with deuterium atoms. This will result in selective deuterium incorporation at the para position.

Step 5: Finally, remove the directing group introduced in Step 3 to regenerate the benzene ring with deuterium atoms at the para positions. For example, if a methyl group was used, perform a demethylation reaction. The final product will be p-dideuteriobenzene (C₆H₄D₂).

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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 in organic chemistry where an electrophile replaces a hydrogen atom on an aromatic ring, such as benzene. This process is crucial for synthesizing various derivatives of benzene, including substituted benzene compounds. Understanding EAS mechanisms, including the role of catalysts and the stability of intermediates, is essential for predicting the outcomes of reactions involving benzene.

Deuteration

Deuteration is the process of replacing hydrogen atoms in a molecule with deuterium, a stable isotope of hydrogen. This is significant in organic synthesis, particularly when creating compounds like p-dideuteriobenzene, as it can alter the physical and chemical properties of the compound. Deuteration can be achieved through various methods, including the use of deuterated reagents in EAS reactions.

Regioselectivity

Regioselectivity refers to the preference of a chemical reaction to yield one structural isomer over others when multiple possibilities exist. In the context of synthesizing p-dideuteriobenzene from benzene, understanding regioselectivity is vital to ensure that deuterium is introduced at the correct positions on the aromatic ring. This concept is particularly important in EAS reactions, where the directing effects of substituents influence the outcome of the reaction.

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