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

Benzyne

Organic Chemistry

19. Reactions of Aromatics: EAS and Beyond

Benzyne

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2:40 minutes

Problem 44b

Textbook Question

Show how the following compounds can be prepared from the given starting material.
b.

Verified step by step guidance

Step 1: Begin with the starting material, pyridine. Pyridine is an aromatic heterocyclic compound with a nitrogen atom in the ring. The target molecule requires substitution at two positions: bromination at the 3-position and amination at the 4-position.

Step 2: Perform selective bromination of pyridine. Use a brominating agent such as Br2 in the presence of a catalyst like FeBr3 or AlBr3. This reaction introduces a bromine atom at the 3-position of pyridine due to the electronic effects of the nitrogen atom, which directs substitution to the meta position.

Step 3: Introduce the amino group at the 4-position. This can be achieved through nucleophilic substitution. First, convert the bromine atom at the 3-position into a leaving group by activating the pyridine ring. Then, use ammonia (NH3) or an amine source to replace the leaving group with an amino group at the 4-position.

Step 4: Ensure regioselectivity during the amination step. The nitrogen atom in pyridine influences the reactivity of the ring, and the reaction conditions must be carefully controlled to avoid substitution at undesired positions.

Step 5: Purify the final product using techniques such as recrystallization or chromatography to isolate 3-bromo-4-aminopyridine. Confirm the structure using spectroscopic methods like NMR or IR to ensure the correct substitution pattern.

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Key Concepts

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

Synthetic Pathways

Synthetic pathways refer to the series of chemical reactions that transform a starting material into a desired product. Understanding these pathways is crucial for predicting how specific compounds can be synthesized, as they involve various reaction mechanisms, reagents, and conditions that dictate the outcome of the synthesis.

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Identifying functional groups in both the starting material and the target compounds is essential for determining the appropriate reactions and reagents needed for synthesis.

Reaction Mechanisms

Reaction mechanisms describe the step-by-step sequence of events that occur during a chemical reaction. A solid understanding of these mechanisms allows chemists to predict the products of reactions, optimize conditions, and troubleshoot potential issues in the synthesis process.

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Related Practice

Textbook Question

What are the products of the following reactions?

Textbook Question

Propose a mechanism for the following reaction:

Textbook Question

One of the following compounds undergoes electrophilic aromatic substitution predominantly at C-3, and one undergoes electrophilic aromatic substitution predominantly at C-4. Which is which?

Textbook Question

b. At what position does pyridine-N-oxide undergo electrophilic aromatic substitution?

Textbook Question

Assume that H_a is the proton removed in the first step of the benzyne mechanism with p-chlorotoluene. Draw the benzyne intermediate and identify the two products that will result.

Textbook Question

Predict the product(s) of the following nucleophilic aromatic substitution reactions occurring by the benzyne mechanism.

(b)

Textbook Question

Addition by the benzyne mechanism is not usually regioselective. Explain the fact that the reaction shown is highly regioselective for the product shown.

Multiple Choice

Which is the major product for the following reaction?

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Show how the following compounds can be prepared from the given starting material.b.

Key Concepts

Synthetic Pathways

Functional Groups

Reaction Mechanisms

Watch next

Show how the following compounds can be prepared from the given starting material.
b.