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

Diazo Replacement Reactions

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

Diazo Replacement Reactions

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0:59 minutes

Problem 25f

Textbook Question

Show how you would convert aniline to the following compounds.
(f) benzonitrile

Verified step by step guidance

Step 1: Begin with aniline (C₆H₅NH₂) as the starting material. Aniline contains an amino group (-NH₂) attached to a benzene ring.

Step 2: Protect the amino group by converting it into a diazonium salt. This is achieved by reacting aniline with sodium nitrite (NaNO₂) and hydrochloric acid (HCl) at 0–5°C. The reaction forms benzene diazonium chloride (C₆H₅N₂⁺Cl⁻). The reaction can be represented as: C₆H₅NH₂ + NaNO₂ + 2HCl → C₆H₅N₂⁺Cl⁻ + 2H₂O.

Step 3: Perform a Sandmeyer reaction to replace the diazonium group (-N₂⁺) with a cyano group (-CN). This is done by treating the benzene diazonium chloride with copper(I) cyanide (CuCN) in the presence of potassium cyanide (KCN). The reaction produces benzonitrile (C₆H₅CN) as the product.

Step 4: Isolate and purify the benzonitrile product. This can be done using standard organic purification techniques such as distillation or recrystallization, depending on the physical properties of the product.

Step 5: Verify the structure of the product using spectroscopic techniques such as IR spectroscopy (look for the characteristic C≡N stretching vibration around 2200–2250 cm⁻¹) and NMR spectroscopy to confirm the successful conversion of aniline to benzonitrile.

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Key Concepts

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

Aniline Structure and Reactivity

Aniline is an aromatic amine with the formula C6H5NH2. Its amino group (-NH2) is a strong activating group for electrophilic aromatic substitution reactions, making the benzene ring more reactive towards electrophiles. Understanding the structure and reactivity of aniline is crucial for determining the appropriate reaction pathways to convert it into other compounds.

Nitration and Electrophilic Substitution

Nitration is a common electrophilic aromatic substitution reaction where a nitro group (-NO2) is introduced into an aromatic ring. This reaction typically involves the use of a nitrating mixture (concentrated HNO3 and H2SO4). In the context of converting aniline to benzonitrile, nitration can be a preliminary step to introduce a nitro group, which can then be further transformed into a nitrile group.

Conversion of Nitro Compounds to Nitriles

The conversion of nitro compounds to nitriles can be achieved through a reduction followed by dehydration. For example, nitroaniline can be reduced to an amine and then treated with a dehydrating agent, such as phosphorus oxychloride (POCl3), to form the corresponding nitrile. This transformation is essential for completing the conversion of aniline to benzonitrile.

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