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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5:18 minutes

Problem 11

Textbook Question

Propose a mechanism for the reaction of benzyl acetate with methylamine. Label the attacking nucleophile and the leaving group, and draw the transition state in which the leaving group leaves.

Verified step by step guidance

Step 1: Identify the functional groups in benzyl acetate. Benzyl acetate is an ester, which contains a carbonyl group (C=O) bonded to an oxygen atom. Methylamine (CH3NH2) is an amine and acts as a nucleophile due to the lone pair of electrons on the nitrogen atom.

Step 2: Recognize the nucleophilic attack. Methylamine (CH3NH2) will act as the attacking nucleophile, targeting the electrophilic carbon of the carbonyl group in benzyl acetate. The lone pair on the nitrogen of methylamine will attack the carbonyl carbon, forming a tetrahedral intermediate.

Step 3: Label the leaving group. In this reaction, the leaving group is the acetate ion (CH3COO−), which is formed when the bond between the carbonyl carbon and the oxygen of the ester breaks during the reaction.

Step 4: Draw the transition state. The transition state involves partial bonds between the nucleophile (methylamine) and the carbonyl carbon, as well as partial bonds between the carbonyl carbon and the leaving group (acetate ion). This state represents the point of highest energy during the reaction.

Step 5: Complete the mechanism. After the transition state, the tetrahedral intermediate collapses, expelling the acetate ion as the leaving group and forming the final product, which is benzyl methylamide. Ensure to show all curved arrows indicating electron movement throughout the mechanism.

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Key Concepts

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

Nucleophilic Substitution Mechanism

Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile attacks an electrophile, resulting in the replacement of a leaving group. In the case of benzyl acetate reacting with methylamine, methylamine acts as the nucleophile, attacking the carbon atom bonded to the acetate group. Understanding this mechanism is crucial for predicting the outcome of the reaction and the stability of intermediates.

Leaving Groups

A leaving group is an atom or group that can depart from the parent molecule during a chemical reaction, taking with it the electrons that were shared with the parent. In the reaction of benzyl acetate, the acetate group (-OAc) serves as the leaving group. The ability of a leaving group to stabilize the negative charge after departure is key to the reaction's feasibility and rate.

Transition State

The transition state is a high-energy, unstable arrangement of atoms that occurs during a chemical reaction, representing the point at which reactants are transformed into products. In the context of the reaction between benzyl acetate and methylamine, drawing the transition state involves illustrating the moment when the nucleophile is forming a bond with the carbon atom while the leaving group is departing. This concept is essential for understanding the energy profile and kinetics of the reaction.

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