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

26. Amines

Amines by Reduction

Organic Chemistry

26. Amines

Amines by Reduction

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5:38 minutes

Problem 30e

Textbook Question

Show how you would accomplish the following synthetic conversions.
(e) (R)-2-bromobutane → (S)-butan-2-amine

Verified step by step guidance

Identify the starting material and the target product. The starting material is (R)-2-bromobutane, and the target product is (S)-butan-2-amine. This conversion involves replacing the bromine atom with an amine group (-NH₂) while inverting the stereochemistry from (R) to (S).

Perform a nucleophilic substitution reaction (SN2) to replace the bromine atom with an azide group (-N₃). Use sodium azide (NaN₃) as the nucleophile. The SN2 mechanism will invert the stereochemistry, converting the (R)-2-bromobutane to (S)-2-azidobutane.

Reduce the azide group (-N₃) to an amine group (-NH₂). This can be achieved using a reducing agent such as lithium aluminum hydride (LiAlH₄) or catalytic hydrogenation (H₂ with a metal catalyst like Pd/C). The reduction does not affect the stereochemistry, so the (S)-configuration is retained.

Verify the stereochemistry of the product. The reduction step does not alter the stereochemistry, so the final product will be (S)-butan-2-amine.

Summarize the synthetic route: (R)-2-bromobutane → (S)-2-azidobutane (via SN2 with NaN₃) → (S)-butan-2-amine (via reduction with LiAlH₄ or H₂/Pd).

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Key Concepts

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

Stereochemistry

Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In this question, understanding the difference between (R) and (S) configurations is crucial, as it determines the specific stereoisomer being synthesized. The conversion from (R)-2-bromobutane to (S)-butan-2-amine involves a change in stereochemistry, which can be achieved through specific reactions that manipulate the orientation of the substituents around the chiral center.

Nucleophilic Substitution Reactions

Nucleophilic substitution reactions are fundamental organic reactions where a nucleophile replaces a leaving group in a molecule. In this case, the bromine atom in (R)-2-bromobutane acts as a leaving group, and the amine group will act as the nucleophile. Understanding the mechanisms of these reactions, such as SN1 and SN2 pathways, is essential for predicting the outcome and stereochemical configuration of the product.

Inversion of Configuration

Inversion of configuration refers to the process where the stereochemistry at a chiral center is reversed during a chemical reaction. This is particularly relevant in the conversion of (R)-2-bromobutane to (S)-butan-2-amine, as the nucleophilic substitution will lead to an inversion at the chiral center. Recognizing how this inversion occurs, especially in SN2 reactions, is vital for achieving the desired stereoisomer in the synthesis.

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