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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4:11 minutes

Problem 47a

Textbook Question

The two most general amine syntheses are the reductive amination of carbonyl compounds and the reduction of amides. Show how these techniques can be used to accomplish the following syntheses.
(a) benzoic acid → benzylamine

Verified step by step guidance

Step 1: Convert benzoic acid to benzaldehyde. This can be achieved by reducing the carboxylic acid group (-COOH) to an aldehyde (-CHO). A common reagent for this transformation is DIBAL-H (diisobutylaluminum hydride) under controlled conditions.

Step 2: Perform reductive amination on benzaldehyde. In this step, react benzaldehyde with ammonia (NH₃) to form an imine intermediate. This reaction typically requires acidic conditions to facilitate the formation of the imine.

Step 3: Reduce the imine intermediate to benzylamine. Use a reducing agent such as sodium cyanoborohydride (NaBH₃CN) or hydrogen gas (H₂) with a metal catalyst (e.g., Pd/C) to convert the imine to the amine group (-NH₂).

Step 4: Purify the benzylamine product. After the reaction is complete, isolate and purify the benzylamine using techniques such as distillation or recrystallization, depending on the physical properties of the product.

Step 5: Verify the structure of benzylamine. Use spectroscopic methods such as NMR (nuclear magnetic resonance) or IR (infrared spectroscopy) to confirm the successful synthesis of benzylamine from benzoic acid.

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Key Concepts

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

Reductive Amination

Reductive amination is a chemical reaction that involves the conversion of a carbonyl compound, such as an aldehyde or ketone, into an amine. This process typically involves the formation of an imine or enamine intermediate, which is then reduced to yield the corresponding amine. In the context of the question, this technique can be applied to convert benzoic acid into benzylamine by first forming an intermediate and then reducing it.

Reduction of Amides

The reduction of amides is a method used to convert amides into amines. This reaction typically involves the use of reducing agents such as lithium aluminum hydride (LiAlH4) or borane (BH3). In the case of the synthesis from benzoic acid to benzylamine, the carboxylic acid can be converted to an amide first, which can then be reduced to yield the desired amine product.

Functional Group Transformation

Functional group transformation refers to the process of converting one functional group into another through chemical reactions. In organic synthesis, this is crucial for modifying molecules to achieve desired properties or structures. The transformation of benzoic acid (a carboxylic acid) to benzylamine (an amine) involves multiple steps, including the conversion to an amide and subsequent reduction, showcasing the importance of understanding functional groups in organic chemistry.

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Related Practice

Textbook Question

Show how m-toluidine can be converted to the following compounds, using any necessary reagents.

(b)

Textbook Question

Show how you would accomplish the following synthetic conversions.

(d) pentanoic acid → hexan-1-amine

Textbook Question

Show how you would accomplish the following synthetic conversions.

(e) (R)-2-bromobutane → (S)-butan-2-amine

Textbook Question

Show how you can synthesize the following tertiary amine three different ways, each using a different secondary amine and adding the final substituent by (b) acylation–reduction (3 ways).

Textbook Question

Reduction of two different carboxylic acid derivatives with LiAlH₄ would give the amine shown. Identify these carboxylic acid derivatives.

Textbook Question

Predict the product of the following reaction sequences.

(b)

Textbook Question

Give the expected products of lithium aluminum hydride reduction of the following compounds (followed by hydrolysis).

(a) butyronitrile

(b) N-cyclohexylacetamide

Textbook Question

Predict the products of the following reactions.

(e)