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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5:46 minutes

Problem 73

Textbook Question

Write the mechanism for the reaction of an amino acid with di-tert-butyl dicarbonate.

Verified step by step guidance

Identify the functional groups in the amino acid: The amino acid contains an amine group (-NH2) and a carboxylic acid group (-COOH). The reaction will involve the amine group reacting with di-tert-butyl dicarbonate (Boc2O).

Understand the role of di-tert-butyl dicarbonate: Boc2O is a reagent used to protect the amine group by converting it into a Boc-protected amine. This reaction prevents the amine group from participating in further reactions.

Initiate the reaction: The lone pair of electrons on the nitrogen atom in the amine group attacks one of the carbonyl carbons in Boc2O. This is a nucleophilic attack, as the nitrogen acts as a nucleophile and the carbonyl carbon is electrophilic.

Form the tetrahedral intermediate: The nucleophilic attack results in the formation of a tetrahedral intermediate. One of the tert-butyl carbonate groups is displaced as a leaving group during this step.

Complete the reaction: The intermediate collapses, leading to the formation of the Boc-protected amine. The final product is the amino acid with its amine group protected as an N-Boc derivative, and tert-butanol is released as a byproduct.

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Key Concepts

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

Amino Acid Structure

Amino acids are organic compounds that serve as the building blocks of proteins. They consist of a central carbon atom bonded to an amino group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and a variable R group that determines the specific properties of each amino acid. Understanding the structure of amino acids is crucial for analyzing their reactivity and interactions with other chemical species.

Protecting Groups in Organic Synthesis

Protecting groups are temporary modifications used in organic synthesis to prevent certain functional groups from reacting during a chemical reaction. In the case of di-tert-butyl dicarbonate (Boc2O), it acts as a protecting group for the amino group of an amino acid, allowing for selective reactions without interference from the amine. This concept is essential for controlling the reactivity of functional groups in complex organic transformations.

Mechanism of Nucleophilic Acyl Substitution

The reaction between an amino acid and di-tert-butyl dicarbonate involves nucleophilic acyl substitution, where the nucleophilic amino group attacks the electrophilic carbonyl carbon of the dicarbonate. This mechanism typically includes the formation of a tetrahedral intermediate, followed by the elimination of a leaving group. Understanding this mechanism is vital for predicting the outcome of the reaction and the stability of the resulting products.

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The reaction of a nitrile with an alcohol in the presence of a strong acid forms an N-substituted amide. This reaction, known as the Ritter reaction, does not work with primary alcohols.

a. Propose a mechanism for the Ritter reaction.

Textbook Question

The reaction of a nitrile with an alcohol in the presence of a strong acid forms an N-substituted amide. This reaction, known as the Ritter reaction, does not work with primary alcohols.

b. Why does the Ritter reaction not work with primary alcohols?

Textbook Question

The reaction of a nitrile with an alcohol in the presence of a strong acid forms an N-substituted amide. This reaction, known as the Ritter reaction, does not work with primary alcohols.

c. How does the Ritter reaction differ from the acid-catalyzed hydrolysis of a nitrile to form an amide?

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