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

11. Radical Reactions

Anti Markovnikov Addition of Br

Organic Chemistry

11. Radical Reactions

Anti Markovnikov Addition of Br

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3:12 minutes

Problem 14c,d

Textbook Question

What is the major product of the reaction of 2-methyl-2-butene with each of the following reagents?
c. HBr + peroxide
d. HCl + peroxide

Verified step by step guidance

Identify the type of reaction: The reaction involves an alkene (2-methyl-2-butene) reacting with hydrogen halides (HBr and HCl) in the presence of peroxides. The presence of peroxides indicates that the reaction will proceed via a free radical mechanism, specifically the anti-Markovnikov addition of the halogen.

Understand the anti-Markovnikov rule: In the presence of peroxides, the addition of HBr to an alkene follows the anti-Markovnikov rule. This means the bromine atom will add to the less substituted carbon of the double bond, while the hydrogen atom will add to the more substituted carbon. This occurs due to the formation of a bromine radical during the reaction.

Analyze the reaction with HBr + peroxide: For 2-methyl-2-butene, the double bond is between the second and third carbons. The less substituted carbon is the terminal carbon (C1), so the bromine atom will attach to C1, and the hydrogen atom will attach to the more substituted carbon (C2). This results in the formation of the anti-Markovnikov product.

Analyze the reaction with HCl + peroxide: Unlike HBr, HCl does not undergo a free radical mechanism in the presence of peroxides. This is because the bond dissociation energy of HCl is higher than that of HBr, making it less favorable to form a chlorine radical. Therefore, the reaction will proceed via the standard Markovnikov addition mechanism, where the hydrogen atom adds to the less substituted carbon (C1), and the chlorine atom adds to the more substituted carbon (C2).

Summarize the products: For HBr + peroxide, the major product is the anti-Markovnikov addition product, where bromine is attached to the less substituted carbon. For HCl + peroxide, the major product is the Markovnikov addition product, where chlorine is attached to the more substituted carbon.

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Key Concepts

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

Markovnikov's Rule

Markovnikov's Rule states that in the addition of HX to an alkene, the hydrogen atom (H) will attach to the carbon with the greater number of hydrogen atoms already attached, while the halide (X) will attach to the carbon with fewer hydrogen atoms. This rule helps predict the major product of electrophilic addition reactions involving alkenes.

Anti-Markovnikov Addition

Anti-Markovnikov addition occurs when the addition of HX to an alkene results in the halide attaching to the more substituted carbon, contrary to Markovnikov's Rule. This is often facilitated by the presence of peroxides, which lead to the formation of free radicals and favor the formation of the less stable radical intermediate.

Free Radical Mechanism

The free radical mechanism involves the formation of free radicals during a chemical reaction, which are highly reactive species with unpaired electrons. In the context of alkene reactions with HBr or HCl in the presence of peroxides, this mechanism leads to the anti-Markovnikov product due to the stability of the radical intermediates formed during the reaction.

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(b)

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(d)

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