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

1. A Review of General Chemistry

Resonance Structures

Organic Chemistry

1. A Review of General Chemistry

Resonance Structures

Previous problemNext problem

6:48 minutes

Problem 19

Textbook Question

Draw the important resonance contributors for both resonance-stabilized cations (in brackets) in the mechanism for acid-catalyzed hydrolysis of an amide.

Verified step by step guidance

Identify the structure of the amide and the acid catalyst. The amide has the general structure R-C(=O)-NR'R'', where the carbonyl group (C=O) and the nitrogen atom are key players in resonance. The acid catalyst (H⁺) will protonate the amide, initiating the reaction.

Protonate the carbonyl oxygen atom of the amide. This step increases the electrophilicity of the carbonyl carbon, making it more susceptible to nucleophilic attack. Represent this step by showing the resonance structure where the positive charge is delocalized onto the oxygen atom.

Draw the resonance structure where the lone pair of electrons on the nitrogen atom delocalizes into the carbonyl group. This creates a resonance-stabilized cation where the positive charge is now on the nitrogen atom. Use curved arrows to indicate the movement of electrons.

Show the resonance contributor where the nitrogen atom regains its lone pair, and the positive charge is delocalized back onto the oxygen atom. This demonstrates the delocalization of the positive charge between the oxygen and nitrogen atoms, stabilizing the intermediate.

Repeat the process for the second resonance-stabilized cation formed later in the mechanism. This occurs after the nucleophilic attack by water and subsequent proton transfers. Focus on the delocalization of the positive charge between the oxygen and nitrogen atoms in this intermediate as well.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

Resonance Structures

Resonance structures are different Lewis structures for the same molecule that depict the delocalization of electrons. They help illustrate how electrons can be distributed across various atoms, affecting the molecule's stability and reactivity. In the context of resonance-stabilized cations, these structures show how positive charge can be shared among multiple atoms, enhancing stability.

Cation Stability

Cation stability refers to the relative stability of positively charged species (cations) based on their electronic structure and surrounding environment. Factors influencing cation stability include the degree of alkyl substitution, resonance effects, and inductive effects. Resonance-stabilized cations are generally more stable due to the delocalization of the positive charge across multiple atoms.

Acid-Catalyzed Hydrolysis

Acid-catalyzed hydrolysis is a chemical reaction where an acid facilitates the breakdown of a compound, such as an amide, into its constituent parts, typically involving water. In this process, the acid donates a proton, enhancing the electrophilicity of the amide carbon, which can lead to the formation of resonance-stabilized cations during the reaction mechanism. Understanding this mechanism is crucial for predicting the behavior of the reactants.

Watch next

Master The rules you need for resonance: with a bite sized video explanation from Johnny

Start learning

Related Videos

Related Practice

Textbook Question

Another way the preceding might be presented is to say that the minor resonance structure(s) reveal the reactivity of a molecule. Show how the minor resonance structure(s) can help us understand that the following reactions occur with the regioselectivity shown.

(a)

(b)

(c)

Textbook Question

A carboxylic acid has two oxygen atoms, each with two nonbonding pairs of electrons.

(a) Draw the resonance forms of a carboxylic acid that is protonated on the hydroxy oxygen atom.

(b) Compare the resonance forms with those given previously for an acid protonated on the carbonyl oxygen atom.

Textbook Question

Draw the resonance contributors of the peptide bond in the less stable configuration.

Textbook Question

Draw all possible resonance structures for the reactive intermediates shown.

(b)

Textbook Question

Draw two important resonance structures involving the lone pair on oxygen for the molecule shown. Which carbons are most likely to act as nucleophiles?

Textbook Question

Draw two important resonance structures involving the C―O π bond for the molecule shown. To which carbons would you expect a nucleophile to add?

Textbook Question

Use resonance forms to show delocalization of the negative charge in the Ruhemann's purple anion.

Textbook Question

Draw all possible resonance structures for the reactive intermediates shown.

(c)

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap