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

10. Addition Reactions

Hydrohalogenation

Organic Chemistry

10. Addition Reactions

Hydrohalogenation

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5:41 minutes

Problem 61k(iii)

Textbook Question

Predict the product(s) that would result when the alkenes shown here are allowed to react under the following conditions: (iii) HBr, H₂O₂
(k)

Verified step by step guidance

Identify the type of reaction: The reaction involves an alkene reacting with HBr in the presence of H₂O₂. This is a free radical addition reaction, which follows the anti-Markovnikov rule due to the presence of H₂O₂ (peroxide).

Understand the anti-Markovnikov rule: In the presence of peroxides, the bromine atom (Br) will add to the less substituted carbon of the double bond, while the hydrogen atom (H) will add to the more substituted carbon. This is the opposite of the Markovnikov rule.

Initiate the reaction mechanism: The reaction begins with the homolytic cleavage of the peroxide (H₂O₂) to generate free radicals. These radicals then initiate the formation of a bromine radical (Br•) from HBr.

Propagate the reaction: The bromine radical (Br•) reacts with the alkene, breaking the π bond and forming a new carbon-bromine bond at the less substituted carbon. This generates a carbon-centered radical on the more substituted carbon.

Complete the reaction: The carbon-centered radical reacts with another HBr molecule, abstracting a hydrogen atom (H•) to form the final product. The product will have the bromine atom attached to the less substituted carbon of the original double bond.

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Key Concepts

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

Electrophilic Addition

Electrophilic addition is a fundamental reaction mechanism in organic chemistry where an electrophile reacts with a nucleophile, typically involving alkenes. In the presence of HBr, the double bond of the alkene acts as a nucleophile, attacking the electrophilic hydrogen atom, leading to the formation of a carbocation intermediate. This process is crucial for predicting the products of reactions involving alkenes.

Anti-Markovnikov's Rule

Anti-Markovnikov's Rule states that in the addition of HX to alkenes, the hydrogen atom will add to the less substituted carbon atom of the double bond when a peroxide (like H₂O₂) is present. This contrasts with Markovnikov's rule, where the hydrogen adds to the more substituted carbon. Understanding this rule is essential for predicting the correct product distribution in reactions involving HBr and peroxides.

Radical Mechanism

The radical mechanism involves the formation of free radicals during a chemical reaction, which can lead to different product outcomes compared to ionic mechanisms. In the presence of H₂O₂, the reaction proceeds via a radical pathway, generating bromine radicals that add to the alkene. This mechanism is key to understanding how the presence of peroxides alters the typical electrophilic addition reactions of alkenes.

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