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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5:00 minutes

Problem 84c,d

Textbook Question

What is the major product of the reaction of each of the following with HBr?
c.
d.

Verified step by step guidance

Step 1: Analyze the structure of the given compounds. Both structures contain alkenes, which are reactive towards HBr via electrophilic addition. The first structure has a branched alkene, while the second structure has a cyclopentane ring with an alkene side chain.

Step 2: Recall the mechanism of electrophilic addition of HBr to alkenes. The reaction proceeds via the formation of a carbocation intermediate. The regioselectivity follows Markovnikov's rule, where the hydrogen atom from HBr adds to the carbon of the double bond with more hydrogens, and the bromine adds to the carbon with fewer hydrogens.

Step 3: For the first structure, identify the double bond and determine the more substituted carbon. The carbocation will form on the more substituted carbon after the hydrogen adds to the less substituted carbon.

Step 4: For the second structure, focus on the alkene side chain. Apply Markovnikov's rule to determine the major product. The hydrogen will add to the terminal carbon of the double bond, forming a carbocation on the adjacent carbon, which is more stable due to hyperconjugation and inductive effects.

Step 5: Consider any possible rearrangements of the carbocation intermediates for both structures. If a more stable carbocation can form via hydride or alkyl shifts, the reaction may proceed through that pathway before bromine adds to the carbocation to form the final product.

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Key Concepts

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

Electrophilic Addition Reactions

Electrophilic addition reactions are a fundamental type of reaction in organic chemistry where an electrophile reacts with a nucleophile, typically involving alkenes or alkynes. In the presence of HBr, the double or triple bond of the hydrocarbon acts as a nucleophile, attacking the electrophilic hydrogen atom, leading to the formation of a more stable product. Understanding this mechanism is crucial for predicting the major product formed in such reactions.

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 the greater number of hydrogen atoms already attached. This rule helps predict the regioselectivity of the reaction, guiding chemists in determining which product will be the major one when HBr reacts with unsymmetrical alkenes.

Carbocation Stability

Carbocation stability is a key concept in organic chemistry that refers to the relative stability of positively charged carbon species. The stability of a carbocation increases with the number of alkyl groups attached to the positively charged carbon, as these groups can donate electron density through inductive effects and hyperconjugation. This concept is essential for predicting the pathway and major product of reactions involving HBr, as the formation of more stable carbocations often leads to the favored product.

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