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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Problem 24a

Textbook Question

Propose a mechanism for the coupling of acetic acid and aniline using DCC as a coupling agent.

Verified step by step guidance

Identify the role of DCC (dicyclohexylcarbodiimide) in the reaction: DCC is a coupling agent that activates the carboxylic acid group of acetic acid, making it more reactive toward nucleophilic attack by the amine group of aniline.

Step 1: Activation of acetic acid by DCC. The lone pair of electrons on the oxygen atom of the carboxylic acid group in acetic acid attacks the carbon atom of the carbodiimide group in DCC, forming an O-acylisourea intermediate. This intermediate is highly reactive and facilitates the coupling reaction.

Step 2: Nucleophilic attack by aniline. The lone pair of electrons on the nitrogen atom of aniline attacks the carbonyl carbon of the O-acylisourea intermediate, forming a tetrahedral intermediate.

Step 3: Collapse of the tetrahedral intermediate. The tetrahedral intermediate collapses, leading to the formation of the amide bond between acetic acid and aniline, and dicyclohexylurea (DCU) as a byproduct.

Step 4: Final product formation. The reaction results in the formation of acetanilide (an amide) as the final product, along with DCU, which can be removed by filtration due to its insolubility in many solvents.

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Key Concepts

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

Coupling Reactions

Coupling reactions involve the formation of a new bond between two molecules, typically involving a nucleophile and an electrophile. In this context, acetic acid acts as a carboxylic acid nucleophile, while aniline serves as an amine nucleophile. Understanding the nature of these reactants and their reactivity is crucial for proposing a mechanism.

DCC (Dicyclohexylcarbodiimide)

DCC is a commonly used coupling agent in organic synthesis that facilitates the formation of amide bonds between carboxylic acids and amines. It activates the carboxylic acid by converting it into a more reactive intermediate, allowing for the nucleophilic attack by the amine. Familiarity with DCC's role and mechanism is essential for understanding how it aids in the coupling of acetic acid and aniline.

Mechanism of Amide Formation

The mechanism of amide formation typically involves the nucleophilic attack of an amine on the activated carboxylic acid. In the presence of DCC, the carboxylic acid forms an O-acylurea intermediate, which is then attacked by the amine, leading to the formation of the amide bond and the release of dicyclohexylurea as a byproduct. Understanding this stepwise process is vital for accurately proposing the overall reaction mechanism.

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Related Practice

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.

Textbook Question

Show how you can synthesize the following compounds starting with benzene, toluene, and alcohols containing no more than four carbon atoms as your organic starting materials. Assume that para is the major product (and separable from ortho) in ortho, para mixtures.

(b) N-methylbutan-1-amine

Textbook Question

(a) pentan-1-amine

Textbook Question

Using any necessary reagents, show how you can accomplish the following multistep syntheses.

(c)

Multiple Choice

Predict the major, organic product for the following reaction.

Multiple Choice

Which of the following successfully synthesizes the given target?

Textbook Question

How can the following compounds be prepared from the given starting materials?