One of the more reactive species we will study in organic chemistry is the carbene (molecular formula of CH 2 ). The carbene can react as both a Lewis acid and a Lewis base. Explain these properties.

All right. Hi, everyone. So this question says that phenyl methylene is an example of a carbine with the molecular formula C seven H six. It can act as both a Luis acid and a Luis base. Why? And here we have four different answer choices labeled A through D. So first, let's go ahead and recall the Lewis acid based definition. A Lewis acid base reaction is classified by the exchange of a lone pair of electrons. So a Luis acid is a chemical compound that is going to accept the electron pair. On the other hand, the Lewis base is a species that donates the electron pair. And so by definition, right, a Luis acid must be electron deficient, meaning it has an incomplete outset whereas the lowest base must be electron rich, most commonly containing a lone pair of electrons. Now, carbs are a very interesting type of molecule because carbs contain neutral carbon atoms that have one lone pair of electrons and only two covalent bonds. So here, let's examine the octet of the carby. As mentioned previously, the car be only has two covalent bonds, one to the carbon of the benzene ring and the other to hydrogen, each bond contributes two electrons each, which means that there are four in total. And if we added the two from the lone pair, the carbon of the carb only has six valence electrons. And because it has only six valence electrons and not eight, this carbon has an incomplete octet, which means it is electron deficient. And so from this right, we know that the carbine can behave as a luis acid because it can attain another electron pair to complete the octet. Now, on the other hand, despite carbon being neutral, it still has a lone pair. And because it has a loan pair, it could donate this loan pair to create a bond with another atom. And so because it could donate its lone pair, it could also behave as a low base and there you have it. So our answer is going to be option a in the multiple choice, it can act as a le bas or rather as a Lewis acid and a Lewis base because it can gain an electron pair and donate a lone pair. So with that being said, thank you so very much for watching. And I hope you found this helpful.

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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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Problem 74

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.

Verified step by step guidance

Understand the concept of a carbene: A carbene is a reactive intermediate with the general formula R₂C, where R can be hydrogen or other substituents. It contains a carbon atom with only six valence electrons, making it electron-deficient and highly reactive.

Explain the Lewis acid behavior: A Lewis acid is a species that can accept a pair of electrons. The carbene has an empty p orbital due to its electron deficiency, which allows it to act as a Lewis acid by accepting electron pairs from nucleophiles.

Explain the Lewis base behavior: A Lewis base is a species that can donate a pair of electrons. The carbene also has a lone pair of electrons on the carbon atom, which can be donated to electrophiles, allowing it to act as a Lewis base.

Discuss the dual reactivity: The ability of the carbene to act as both a Lewis acid and a Lewis base arises from its unique electronic structure—having both an empty orbital and a lone pair of electrons. This dual reactivity makes carbenes versatile intermediates in organic reactions.

Provide examples of reactions: Carbenes can participate in reactions such as cyclopropanation (acting as a Lewis base) or insertion into bonds (acting as a Lewis acid). These reactions highlight the importance of understanding their dual nature in organic chemistry.

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Key Concepts

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

Carbene Structure and Reactivity

Carbenes are neutral species containing a carbon atom with only six valence electrons, making them highly reactive. They exist in two forms: singlet, where the two non-bonding electrons are paired, and triplet, where they are unpaired. This unique electronic configuration allows carbenes to participate in various chemical reactions, often acting as intermediates in organic synthesis.

Lewis Acids and Bases

According to Lewis theory, a Lewis acid is an electron pair acceptor, while a Lewis base is an electron pair donor. Carbenes can exhibit both behaviors due to their electron-deficient nature, allowing them to accept electron pairs from Lewis bases or donate their lone pair of electrons to Lewis acids. This duality is crucial for understanding their reactivity in organic reactions.

Reactivity of Carbenes in Organic Reactions

Carbenes participate in various organic reactions, such as insertion into C-H bonds, cyclopropanation, and addition to alkenes. Their ability to act as both Lewis acids and bases enables them to form new bonds and stabilize reaction intermediates. Understanding these reactivity patterns is essential for predicting the outcomes of reactions involving carbenes in organic synthesis.

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