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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3:29 minutes

Problem 35d

Textbook Question

Provide the expected product for the reaction of each of the following alkenes with (i) HBr and (ii) HBr, H₂O₂.
(d)

Verified step by step guidance

Identify the structure of the alkene in part (d). Alkenes are hydrocarbons with a carbon-carbon double bond, which is the site of reactivity in these reactions.

For the reaction with HBr (hydrobromic acid), apply Markovnikov's rule. This rule states that in the addition of HX to an alkene, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached, and the halide (Br) will attach to the carbon with fewer hydrogen atoms.

Write the mechanism for the reaction with HBr. The double bond will attack the hydrogen in HBr, forming a carbocation intermediate on the more substituted carbon. The bromide ion will then attack the carbocation, resulting in the Markovnikov product.

For the reaction with HBr and H₂O₂ (hydrogen peroxide), apply anti-Markovnikov's rule. In the presence of peroxides, the addition of HBr to alkenes proceeds via a radical mechanism, where the bromine atom attaches to the less substituted carbon.

Write the mechanism for the reaction with HBr and H₂O₂. Initiation begins with the formation of radicals from H₂O₂. The alkene reacts with the bromine radical, forming a new radical on the less substituted carbon. This radical then reacts with HBr, completing the anti-Markovnikov addition.

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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 (where X is a halogen) to an alkene, the hydrogen atom will attach to the carbon with more hydrogen substituents, while the halogen will attach to the carbon with fewer hydrogen substituents. This rule helps predict the major product in electrophilic addition reactions.

Anti-Markovnikov Addition

Anti-Markovnikov addition occurs when HBr is added to an alkene in the presence of peroxides (H₂O₂). The reaction proceeds via a radical mechanism, leading to the bromine atom attaching to the less substituted carbon atom, opposite to Markovnikov's Rule. This results in the formation of the anti-Markovnikov product.

Radical Mechanism

A radical mechanism involves the formation of free radicals, which are highly reactive species with unpaired electrons. In the presence of peroxides, the addition of HBr to alkenes follows a radical pathway, initiating with the homolytic cleavage of the peroxide bond, leading to the generation of bromine radicals that drive the anti-Markovnikov addition.

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Related Practice

Textbook Question

Predict the major products of the following reactions, and propose mechanisms to support your predictions.

(b)

HINT: Remember to write out complete structures, including all bonds and charges, when writing a mechanism or determining the course of a reaction.

Textbook Question

Show how you would accomplish the following synthetic conversions.

(a) but−1−ene → 1−bromobutane

(b) but−1−ene → 2−bromobutane

Textbook Question

Provide the expected product for the reaction of each of the following alkenes with (i) HBr and (ii) HBr, H₂O₂

(b)

Textbook Question

Provide the expected product for the reaction of each of the following alkenes with (i) HBr and (ii) HBr, H₂O₂

(c)

Textbook Question

Which reagent system (HBr or HBr, H₂O₂) would you use to carry out the following transformations?

(a)

Textbook Question

Which reagent system (HBr or HBr, H₂O₂) would you use to carry out the following transformations?

(b)

Textbook Question

Provide an arrow-pushing mechanism that rationalizes the formation of each of the products you predicted in Assessment 8.35 (ii). Make sure your mechanism accounts for all products formed, including stereoisomers and regioisomers, where applicable.

Textbook Question

Propose a mechanism for the reaction of pent-1-yne with HBr in the presence of peroxides. Show why anti-Markovnikov orientation results.

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Provide the expected product for the reaction of each of the following alkenes with (i) HBr and (ii) HBr, H2O2.(d)

Key Concepts

Markovnikov's Rule

Anti-Markovnikov Addition

Radical Mechanism

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Provide the expected product for the reaction of each of the following alkenes with (i) HBr and (ii) HBr, H₂O₂.
(d)