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

3. Acids and Bases

Acids and Bases

Organic Chemistry

3. Acids and Bases

Acids and Bases

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2:19 minutes

Problem 5a

Textbook Question

Suggest an arrow-pushing mechanism that accounts for the formation of the following Lewis acid–Lewis base complexes. Label the Lewis acid and Lewis base in each.
(a)

Verified step by step guidance

Step 1: Identify the Lewis acid and Lewis base in the reaction. A Lewis acid is an electron pair acceptor, while a Lewis base is an electron pair donor. Look for species with an empty orbital (Lewis acid) and species with a lone pair of electrons (Lewis base).

Step 2: Draw the starting structures of the reactants. Represent the Lewis acid with its empty orbital and the Lewis base with its lone pair of electrons clearly visible.

Step 3: Use curved arrows to show the movement of electrons. The arrow should originate from the lone pair on the Lewis base and point toward the empty orbital of the Lewis acid, indicating the formation of a coordinate covalent bond.

Step 4: Draw the resulting Lewis acid–Lewis base complex. This should show the Lewis acid and Lewis base connected via the newly formed bond, with the lone pair of electrons now shared between the two species.

Step 5: Verify the mechanism by ensuring that all atoms obey the octet rule (if applicable) and that the electron movement is consistent with the properties of the Lewis acid and Lewis base.

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Key Concepts

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

Lewis Acids and Bases

Lewis acids are species that can accept an electron pair, while Lewis bases are species that can donate an electron pair. This definition expands beyond traditional Brønsted-Lowry acids and bases, allowing for a broader understanding of acid-base reactions. In the context of the question, identifying the Lewis acid and base is crucial for proposing an appropriate arrow-pushing mechanism.

Arrow-Pushing Mechanism

Arrow-pushing mechanisms are a way to illustrate the movement of electrons during chemical reactions. In these diagrams, arrows represent the flow of electron pairs, indicating how bonds are formed or broken. Understanding this mechanism is essential for visualizing how Lewis acids and bases interact to form complexes, as it helps clarify the electron transfer process.

Formation of Lewis Acid-Base Complexes

The formation of Lewis acid-base complexes involves the interaction between a Lewis acid and a Lewis base, resulting in a coordinate covalent bond. This process is characterized by the donation of an electron pair from the base to the acid. Recognizing the nature of these complexes is vital for predicting the stability and reactivity of the resulting species in organic chemistry.

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Related Practice

Textbook Question

Specify which in each pair is the harder Lewis base. Justify your choice beyond just looking at Table 20.2.

(b)

Textbook Question

Specify which in each pair is the harder Lewis acid. Justify your choice beyond just looking at Table 20.2.

(a) Al³⁺ vs. B³⁺

Textbook Question

Suggest an arrow-pushing mechanism for each of the following acid–base reactions.

(d) [an intramolecular reaction]

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

For each of the following reactions, identify the bonds that are broken and formed. Be sure to indicate whether the bond that is broken is a σ bond or a π bond.

(a)

Textbook Question

One of the more reactive species we will study in organic chemistry is the carbene (molecular formula of CH₂). The carbene can react as both a Lewis acid and a Lewis base. Explain these properties.

Textbook Question

Suggest an arrow-pushing mechanism that accounts for the formation of the following Lewis acid–Lewis base complexes. Label the Lewis acid and Lewis base in each.

(b)

Textbook Question

In comparison to CH₃⁺ in Assessment 2.82, the related molecule H₃O⁺ is not a Lewis acid at oxygen. Why?

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