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

22. Carboxylic Acid Derivatives: NAS

Nucleophilic Acyl Substitution

Organic Chemistry

22. Carboxylic Acid Derivatives: NAS

Nucleophilic Acyl Substitution

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4:31 minutes

Problem 35

Textbook Question

Write the mechanism for the acid-catalyzed reaction of an amide with an alcohol to form an ester.

Verified step by step guidance

Step 1: Protonation of the amide oxygen. In the presence of an acid catalyst, the lone pair of electrons on the oxygen atom of the amide group interacts with a proton (H⁺), leading to the formation of a positively charged intermediate. This step increases the electrophilicity of the carbonyl carbon.

Step 2: Nucleophilic attack by the alcohol. The alcohol (R'-OH) acts as a nucleophile and attacks the electrophilic carbonyl carbon of the protonated amide, forming a tetrahedral intermediate. This step involves the breaking of the π-bond in the carbonyl group.

Step 3: Proton transfer within the intermediate. A proton transfer occurs within the tetrahedral intermediate to stabilize the structure. This step prepares the intermediate for the elimination of the leaving group.

Step 4: Elimination of the amine group. The nitrogen atom of the amide group is protonated, making it a better leaving group. The tetrahedral intermediate collapses, expelling the protonated amine (R-NH₃⁺) and reforming the carbonyl group.

Step 5: Deprotonation of the ester product. The ester product (R-COOR') is formed, and a final deprotonation step regenerates the acid catalyst (H⁺), completing the reaction mechanism.

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Key Concepts

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

Acid-Catalyzed Reactions

Acid-catalyzed reactions involve the use of an acid to increase the rate of a chemical reaction. In the context of organic chemistry, acids can protonate nucleophiles or electrophiles, enhancing their reactivity. This is particularly important in reactions involving functional groups like amides and alcohols, where the acid facilitates the formation of a more reactive intermediate.

Amide and Ester Functional Groups

Amides are organic compounds characterized by a carbonyl group (C=O) bonded to a nitrogen atom (N), while esters are formed from the reaction of an alcohol and a carboxylic acid, featuring a carbonyl group bonded to an alkoxy group (R-O). Understanding the structure and reactivity of these functional groups is crucial for predicting the outcome of their reactions, including the transformation of an amide into an ester.

Nucleophilic Acyl Substitution

Nucleophilic acyl substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks a carbonyl carbon, leading to the substitution of a leaving group. In the case of amides reacting with alcohols, the alcohol acts as the nucleophile, attacking the carbonyl carbon of the amide, which is facilitated by the acid catalyst. This mechanism is key to understanding how esters are formed from amides.

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Textbook Question

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