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

35. Transition Metals

Heck Reaction

Organic Chemistry

35. Transition Metals

Heck Reaction

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2:29 minutes

Problem 42a

Textbook Question

Which of the following compounds cannot be prepared by a Heck reaction?

Verified step by step guidance

Step 1: Understand the Heck reaction. The Heck reaction is a palladium-catalyzed coupling reaction between an aryl or vinyl halide and an alkene, resulting in the formation of a substituted alkene. The reaction typically requires a halide (such as bromide or iodide) and an alkene with a terminal double bond.

Step 2: Analyze compound A. Compound A contains two conjugated double bonds. This structure can be formed via a Heck reaction because it involves the coupling of a halide with a terminal alkene, leading to conjugation.

Step 3: Analyze compound B. Compound B contains a double bond in the middle of the chain, not at the terminal position. The Heck reaction generally requires a terminal alkene for the coupling process, so this compound cannot be prepared by a Heck reaction.

Step 4: Analyze compound C. Compound C contains a double bond adjacent to a carbonyl group. This structure can be formed via a Heck reaction because the carbonyl group can stabilize the intermediate formed during the reaction, making it feasible.

Step 5: Conclude that compound B cannot be prepared by a Heck reaction due to the lack of a terminal double bond, which is a key requirement for this reaction.

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Key Concepts

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

Heck Reaction

The Heck reaction is a palladium-catalyzed coupling reaction between an aryl or vinyl halide and an alkene, resulting in the formation of substituted alkenes. This reaction is significant in organic synthesis for constructing complex molecules and is particularly useful for forming carbon-carbon bonds. Understanding the mechanism and the types of substrates that can participate is crucial for predicting the products formed.

Substrate Compatibility

In the context of the Heck reaction, substrate compatibility refers to the ability of specific reactants to undergo the reaction successfully. Factors such as sterics, electronics, and the presence of functional groups influence whether a compound can be synthesized via this method. Recognizing which substrates are suitable helps in determining the feasibility of preparing a desired compound.

Functional Group Tolerance

Functional group tolerance in organic reactions indicates how well different functional groups can coexist in a reaction without interfering with the desired transformation. In the Heck reaction, certain functional groups may be incompatible, leading to side reactions or failure to produce the desired product. Understanding this concept is essential for predicting which compounds can be synthesized and which cannot.

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