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

16. Conjugated Systems

Conjugated Hydrohalogenation (1,2 vs 1,4 addition)

Organic Chemistry

16. Conjugated Systems

Conjugated Hydrohalogenation (1,2 vs 1,4 addition)

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7:40 minutes

Problem 37b

Textbook Question

What are the major 1,2- and 1,4-addition products of the following reaction? Indicate the kinetic and the thermodynamic products.
b.

Verified step by step guidance

Step 1: Analyze the structure provided in the image. The molecule is a conjugated diene, specifically cyclopentadiene, which has two double bonds in conjugation. This makes it suitable for electrophilic addition reactions.

Step 2: Understand the reaction mechanism. In electrophilic addition reactions to conjugated dienes, the electrophile (e.g., H⁺) adds to one of the double bonds, forming a carbocation intermediate. The carbocation can then undergo resonance to form two different intermediates.

Step 3: Identify the possible products. The 1,2-addition product forms when the electrophile adds to one double bond and the nucleophile adds to the adjacent carbon. The 1,4-addition product forms when the electrophile adds to one double bond and the nucleophile adds to the carbon at the other end of the conjugated system.

Step 4: Distinguish between kinetic and thermodynamic control. The kinetic product is formed faster and typically involves the more stable carbocation intermediate. The thermodynamic product is more stable overall and forms under conditions that allow the reaction to reach equilibrium.

Step 5: Predict the major products. The 1,2-addition product is usually the kinetic product because it forms faster due to proximity of the nucleophile to the carbocation. The 1,4-addition product is typically the thermodynamic product because it results in a more substituted and stable double bond.

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Key Concepts

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

1,2- and 1,4-Addition Reactions

1,2- and 1,4-addition reactions refer to the ways in which reagents can add to conjugated systems, such as alkenes. In 1,2-addition, the reagent adds to the first and second carbon atoms of the double bond, while in 1,4-addition, it adds to the first and fourth carbon atoms. These pathways lead to different products, which can have distinct stability and reactivity.

Kinetic vs. Thermodynamic Products

Kinetic and thermodynamic products arise from different reaction conditions and pathways. Kinetic products are formed faster and are typically less stable, while thermodynamic products are more stable and form more slowly. Understanding the conditions that favor one over the other, such as temperature and reaction time, is crucial for predicting the outcome of addition reactions.

Conjugated Systems

Conjugated systems consist of alternating single and double bonds, allowing for delocalization of electrons. This delocalization stabilizes the molecule and influences its reactivity. In the context of addition reactions, the presence of conjugation can affect the regioselectivity and the stability of the resulting products, making it essential to consider when analyzing reaction outcomes.

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Related Practice

Textbook Question

Draw the major products obtained from the reaction of one equivalent of HBr with the following compounds. For each reaction, indicate the kinetic product and the thermodynamic product.

Textbook Question

What are the products of the following reactions, assuming that one equivalent of each reagent is used in each reaction? Disregard stereoisomers.

Textbook Question

Draw the products obtained from the reaction of one equivalent of HBr with one equivalent of 1,3,5-hexatriene.

a. Which product(s) will predominate if the reaction is under kinetic control?

b. Which product(s) will predominate if the reaction is under thermodynamic control?

Textbook Question

a. How could each of the following compounds be prepared from a hydrocarbon in a single step?

b. What other organic compound would be obtained from each synthesis?

Textbook Question

What are the major 1,2- and 1,4-addition products of the following reaction? Indicate the kinetic and the thermodynamic products.

Textbook Question

What are the products of the following reactions, assuming that one equivalent of each reagent is used in each reaction?

Textbook Question

A student wanted to know whether the greater proximity of the nucleophile to the C-2 carbon in the transition state is what causes the 1,2-addition product to be formed faster when 1,3-butadiene reacts with HCl. Therefore, she decided to investigate the reaction of 2-methyl-1,3-cyclohexadiene with HCl. Her friend told her that she should use 1-methyl-1,3-cyclohexadiene instead. Should she follow her friend's advice?

Textbook Question

The experiment shown next and discussed in Section 8.13 shows that the proximity of the chloride ion to C-2 in the transition state causes the 1,2-addition product to form more rapidly than the 1,4-addition product.

a. Why was it important for the investigators to know that the preceding reaction was being carried out under kinetic control?

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What are the major 1,2- and 1,4-addition products of the following reaction? Indicate the kinetic and the thermodynamic products. b.

Key Concepts

1,2- and 1,4-Addition Reactions

Kinetic vs. Thermodynamic Products

Conjugated Systems

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What are the major 1,2- and 1,4-addition products of the following reaction? Indicate the kinetic and the thermodynamic products.
b.