1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 19m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 18m
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 Acids3h 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

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Hell-Volhard-Zelinski Reaction

Organic Chemistry

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Hell-Volhard-Zelinski Reaction

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2:23 minutes

Problem 17Bruice - 8th Edition

Textbook Question

Draw the products of the following reactions: b. pentanoic acid + PBr3 + Br2, followed by hydrolysis

Verified step by step guidance

Identify the starting material as pentanoic acid, a carboxylic acid with five carbon atoms.

Recognize that PBr3 is used to convert the carboxylic acid into an acyl bromide by replacing the OH group with a Br atom.

Understand that Br2 is used in the Hell-Volhard-Zelinsky (HVZ) reaction to brominate the alpha carbon of the acyl bromide.

Note that hydrolysis with water (H2O) will convert the acyl bromide back to a carboxylic acid, retaining the bromine at the alpha position.

Draw the final product, which is 2-bromopentanoic acid, with a bromine atom on the alpha carbon.

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Key Concepts

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

Reactivity of Carboxylic Acids

Carboxylic acids, like pentanoic acid, are organic compounds characterized by the presence of a carboxyl group (-COOH). They can undergo various reactions, including halogenation and conversion to acid derivatives. Understanding their reactivity is crucial for predicting the products formed when they react with reagents like PBr3 and Br2.

Role of PBr3 in Organic Synthesis

Phosphorus tribromide (PBr3) is commonly used to convert alcohols into alkyl bromides. In this reaction, PBr3 reacts with the hydroxyl group of pentanoic acid, facilitating the substitution of the -OH group with a bromine atom. This step is essential for generating a more reactive intermediate that can further react with bromine.

Hydrolysis of Alkyl Halides

Hydrolysis is a reaction where water is used to break chemical bonds, often resulting in the formation of alcohols from alkyl halides. In this case, after the bromination step, the addition of water leads to the conversion of the alkyl bromide back to an alcohol, completing the reaction sequence and yielding the final products.