Textbook Question
Why is anisole nitrated more rapidly than thioanisole under the same conditions?
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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 62
Which of the following compounds reacts with HBr more rapidly?
Verified step by step guidance1
Step 1: Analyze the chemical structures provided. Both compounds contain a benzene ring with a substituent group attached to the ring and a vinyl group (-CH=CH2) attached to the benzene ring. The first compound has a methyl group (-CH3) attached to the benzene ring, while the second compound has a methoxy group (-CH3O) attached to the benzene ring.
Step 2: Consider the reactivity of the vinyl group (-CH=CH2) with HBr. The reaction typically proceeds via electrophilic addition, where the π-electrons of the double bond attack the proton (H+) from HBr, forming a carbocation intermediate.
Step 3: Evaluate the stability of the carbocation intermediate formed during the reaction. The substituent groups on the benzene ring influence the carbocation stability through resonance and inductive effects. The methoxy group (-CH3O) is an electron-donating group via resonance, which stabilizes the carbocation more effectively than the methyl group (-CH3), which is only weakly electron-donating via inductive effects.
Step 4: Understand that the more stable the carbocation intermediate, the faster the reaction with HBr will proceed. Since the methoxy group stabilizes the carbocation more effectively, the compound with the methoxy group reacts more rapidly with HBr.
Step 5: Conclude that the compound with the methoxy group (-CH3O) attached to the benzene ring reacts with HBr more rapidly than the compound with the methyl group (-CH3) attached to the benzene ring.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Reactivity of Alkenes
The reactivity of alkenes with hydrogen halides like HBr is influenced by the stability of the carbocation intermediate formed during the reaction. More substituted alkenes tend to form more stable carbocations, leading to faster reactions. Understanding the structure of the alkenes in question is crucial for predicting which will react more rapidly.
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Alkene Metathesis Concept 1
Carbocation Stability
Carbocation stability is a key factor in determining the rate of reaction with HBr. Tertiary carbocations are more stable than secondary, which are more stable than primary. The stability is influenced by the inductive effect and hyperconjugation from adjacent alkyl groups, making it essential to analyze the structure of the compounds involved.
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05:58Determining Carbocation Stability
Markovnikov's Rule
Markovnikov's Rule states that when HX (like HBr) adds 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 major product of the reaction and is important for understanding the regioselectivity of the reaction, which can also influence the rate of reaction.
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03:54The 18 and 16 Electron Rule
Related Practice
Textbook Question
Describe two ways to prepare anisole from benzene.
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Textbook Question
Show two pairs of reagents that would each result in formation of the following compound:
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Textbook Question
Show how the following compounds can be synthesized from benzene:
g. p-dideuteriobenzene
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Textbook Question
An aromatic hydrocarbon with a molecular formula of C13H20 has an 1H NMR spectrum with a signal at ~7 ppm that integrates to 5H. It also has two singlets; one of the singlets has 1.5 times the area of the second. What is the structure of the aromatic hydrocarbon?
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Textbook Question
Show how the following compounds can be synthesized from benzene:
a. N,N,N-trimethylanilinium iodide
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