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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2:28 minutes

Problem 20

Textbook Question

What will be the product of the preceding reaction if HBr is used in place of Br₂?

Verified step by step guidance

Step 1: Identify the type of reaction taking place. When HBr is used, it typically undergoes an electrophilic addition reaction with alkenes or alkynes, or a substitution reaction with alcohols or other functional groups. Determine the functional group present in the starting material.

Step 2: Analyze the mechanism of the reaction. If the starting material contains a double bond (alkene), HBr will add across the double bond following Markovnikov's rule, where the hydrogen atom attaches to the carbon with more hydrogens, and the bromine atom attaches to the carbon with fewer hydrogens.

Step 3: Consider the possibility of carbocation rearrangement. If the intermediate carbocation formed during the reaction can rearrange to a more stable carbocation (e.g., tertiary carbocation), this rearrangement will occur before bromine attaches.

Step 4: Write the structure of the product. After the bromine atom attaches to the appropriate carbon, the final product will be a bromoalkane. Ensure the stereochemistry is considered if applicable.

Step 5: Verify the reaction conditions. Confirm that no other reagents or conditions (e.g., peroxides) are present, as these could alter the mechanism (e.g., anti-Markovnikov addition in the presence of peroxides).

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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 or alkynes. In this context, HBr acts as the electrophile, adding across the double bond of an alkene. This process results in the formation of a more stable product, often a bromoalkane, depending on the structure of the starting material.

Markovnikov's Rule

Markovnikov's Rule states that when HX (where X is a halogen) adds to an unsymmetrical alkene, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This rule helps predict the major product of the reaction when HBr is used, leading to the formation of the more stable carbocation intermediate and ultimately the more substituted alkyl halide.

Carbocation Stability

Carbocation stability is a key concept in organic chemistry that refers to the relative stability of positively charged carbon species. Carbocations are stabilized by alkyl groups through hyperconjugation and inductive effects. In the context of the reaction with HBr, the formation of a more stable carbocation intermediate influences the final product, as the reaction pathway will favor the formation of the more substituted and stable carbocation.

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