Textbook Question
Draw a structure for each of the following:
c. a β-keto ester
2
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Ch. 17 - Reactions at the Alpha-Carbon
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
Chapter 18, Problem 49b
Draw the products of the following reactions: b. pentanoic acid + PBr3 + Br2, followed by hydrolysis
Verified step by step guidance1
Step 1: Recognize the starting material, pentanoic acid, which is a carboxylic acid with five carbon atoms. The reaction involves PBr3 and Br2, followed by hydrolysis.
Step 2: Understand the role of PBr3 and Br2. PBr3 converts the carboxylic acid group (-COOH) into an acyl bromide (-COBr). This step activates the molecule for further reaction.
Step 3: The acyl bromide reacts with Br2 in the presence of PBr3, leading to alpha-bromination. This occurs at the alpha-carbon (the carbon adjacent to the carbonyl group) due to its increased reactivity.
Step 4: After alpha-bromination, hydrolysis (reaction with water) converts the acyl bromide back into a carboxylic acid. The bromine atom remains attached to the alpha-carbon.
Step 5: The final product is alpha-bromopentanoic acid, where the bromine atom is attached to the alpha-carbon of the pentanoic acid structure.
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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 halides. Understanding their reactivity is crucial for predicting the products when they react with reagents like PBr3 and Br2.
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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 the subsequent bromination of the resulting compound.
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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. After the initial reaction with PBr3 and Br2, hydrolysis of the resulting alkyl bromide will yield a bromo-substituted carboxylic acid. This step is critical for determining the final products of the reaction sequence.
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Related Practice
Textbook Question
Draw a structure for each of the following: d. the enol tautomer of cyclopentanone
4
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Textbook Question
Draw the products of the following reactions:
c. acetone + LDA/THF: (1) slow addition of ethyl acetate; (2) HCl
1
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Textbook Question
Draw the products of the following reactions: e. diethyl malonate: (1) sodium ethoxide; (2) isobutyl bromide; (3) HCl, H2O + heat
5
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Textbook Question
The 1H NMR chemical shifts of nitromethane, dinitromethane, and trinitromethane are at δ6.10, δ4.33, and δ7.52. Match each chemical shift with the compound. Explain how chemical shift correlates with pKa.
5
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Textbook Question
Draw the products of the following reactions:
a. diethyl heptanedioate: (1) sodium ethoxide; (2) HCl
1
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