Textbook Question
Use the four compounds shown below to answer the following questions:
b. Why is o-fluorobenzoic acid the weakest of the ortho-halo-substituted benzoic acids?
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Ch. 18 - Reactions of Benzene and Substituted Benzenes
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 19, Problem 67a
a. Rank the following esters from most reactive to least reactive in the first slow step of a nucleophilic acyl substitution reaction (formation of the tetrahedral intermediate):
Verified step by step guidance1
Step 1: Understand the reactivity of esters in nucleophilic acyl substitution reactions. The first slow step involves the attack of a nucleophile on the carbonyl carbon, forming a tetrahedral intermediate. The reactivity depends on the electronic effects of substituents attached to the ester group.
Step 2: Analyze the substituents attached to the ester oxygen in each compound. Electron-withdrawing groups (EWGs) increase the electrophilicity of the carbonyl carbon, making it more reactive. Electron-donating groups (EDGs) decrease the electrophilicity, making the ester less reactive.
Step 3: Examine compound A. It has a chlorine atom attached to a benzene ring, which is an electron-withdrawing group. This increases the reactivity of the ester by stabilizing the partial positive charge on the carbonyl carbon.
Step 4: Examine compound B. It has a cyclohexyl group, which is an electron-donating group. This decreases the reactivity of the ester by reducing the electrophilicity of the carbonyl carbon.
Step 5: Compare compound C and D. Compound C has a benzene ring, which is less electron-withdrawing than the chlorinated benzene ring in compound D. Compound D has two chlorine atoms attached to the benzene ring, making it the most electron-withdrawing and therefore the most reactive ester in the series.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Nucleophilic Acyl Substitution
Nucleophilic acyl substitution is a fundamental reaction in organic chemistry where a nucleophile attacks the carbonyl carbon of an acyl compound, leading to the formation of a tetrahedral intermediate. This reaction is characterized by the replacement of a leaving group (often a carboxylic acid derivative) with a nucleophile. The reactivity of the acyl compound is influenced by the nature of the leaving group and the electronic effects of substituents on the carbonyl carbon.
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Nucleophiles and Electrophiles can react in Substitution Reactions.
Reactivity of Esters
The reactivity of esters in nucleophilic acyl substitution is determined by the stability of the leaving group and the electronic environment around the carbonyl. Electron-withdrawing groups, such as halogens, increase the electrophilicity of the carbonyl carbon, making the ester more reactive. Conversely, electron-donating groups can decrease reactivity by stabilizing the carbonyl, making it less susceptible to nucleophilic attack.
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Tetrahedral Intermediate
The tetrahedral intermediate is a key species formed during nucleophilic acyl substitution. It results from the nucleophile's attack on the carbonyl carbon, leading to a temporary four-coordinate structure. The stability of this intermediate is crucial for the reaction's progression; if it is stable, the reaction is more likely to proceed to completion, while an unstable intermediate may lead to a slower reaction or revert to starting materials.
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Related Practice
Textbook Question
A mixture of 0.10 mol benzene and 0.10 mol p-xylene was allowed to react with 0.10 mol nitronium ion until all the nitronium ion was gone. Two products were obtained: 0.002 mol of one and 0.098 mol of the other.
b. Why was more of one product obtained than of the other?
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Textbook Question
b. Rank the same esters from most reactive to least reactive in the second slow step of a nucleophilic acyl substitution reaction (collapse of the tetrahedral intermediate).
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Textbook Question
Use the four compounds shown below to answer the following questions:
a. Why are the ortho-halo-substituted benzoic acids stronger acids than benzoic acid?
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Textbook Question
Show how the following compounds can be synthesized from benzene:
h. p-nitro-N-methylaniline
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Textbook Question
Does m-xylene or p-xylene react more rapidly with Cl2 + FeCl3? Explain your answer.
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