Textbook Question
Which reacts faster in an SN1 reaction?
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Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides
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
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Bruice 8th EditionCh. 9 - Substitution and Elimination Reactions of Alkyl HalidesProblem 39a
Bruice 8th EditionCh. 9 - Substitution and Elimination Reactions of Alkyl HalidesProblem 39aChapter 10, Problem 39a
Which reacts faster in an SN2 reaction?
Verified step by step guidance1
Step 1: Understand the SN2 reaction mechanism. SN2 reactions proceed via a single-step mechanism where the nucleophile attacks the electrophilic carbon and displaces the leaving group simultaneously. The rate of SN2 reactions is highly dependent on steric hindrance around the electrophilic carbon.
Step 2: Analyze the structure of CH3CH2CH2Br. The electrophilic carbon attached to the bromine atom is a primary carbon, meaning it is bonded to only one other carbon atom. Primary carbons experience minimal steric hindrance, making them favorable for SN2 reactions.
Step 3: Analyze the structure of CH3CH2CHCH3 (with Br attached). The electrophilic carbon attached to the bromine atom is a secondary carbon, meaning it is bonded to two other carbon atoms. Secondary carbons experience more steric hindrance compared to primary carbons, which slows down the SN2 reaction rate.
Step 4: Compare steric hindrance between the two molecules. CH3CH2CH2Br has less steric hindrance due to its primary carbon, while CH3CH2CHCH3 has more steric hindrance due to its secondary carbon. Therefore, CH3CH2CH2Br is expected to react faster in an SN2 reaction.
Step 5: Conclude that steric hindrance is the key factor in determining the rate of SN2 reactions. The molecule with the least steric hindrance (CH3CH2CH2Br) will react faster in an SN2 reaction compared to the molecule with more steric hindrance (CH3CH2CHCH3).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
SN2 Reaction Mechanism
The SN2 (substitution nucleophilic bimolecular) reaction is a type of nucleophilic substitution where the nucleophile attacks the electrophile simultaneously as the leaving group departs. This concerted mechanism results in a single transition state and is characterized by a backside attack, leading to inversion of configuration at the carbon center. The rate of the reaction depends on both the concentration of the nucleophile and the substrate.
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Nucleophilicity
Nucleophilicity refers to the strength of a nucleophile, which is determined by its ability to donate an electron pair to an electrophile. Factors influencing nucleophilicity include charge, electronegativity, and solvent effects. Stronger nucleophiles, such as alkoxides or amines, will react faster in SN2 reactions compared to weaker nucleophiles like water or alcohols.
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Steric Hindrance
Steric hindrance is the prevention of reactions due to the spatial arrangement of atoms within a molecule. In SN2 reactions, steric hindrance at the electrophilic carbon can significantly affect the reaction rate; primary substrates react faster than secondary, while tertiary substrates are typically too hindered to undergo SN2. Thus, understanding the structure of the substrate is crucial for predicting reaction outcomes.
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Related Practice
Textbook Question
You were told in [SECTION 7.11] that is best to use a methyl halide or a primary alkyl halide for the reaction of an acetylide ion with an alkyl halide. Explain why this is so.
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Textbook Question
Draw the substitution and elimination products for the following reactions, showing the configuration of each product:
c. 1-chloro-1-methylcyclohexane + CH3O−
d. 1-chloro-1-methylcyclohexane + CH3OH
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Textbook Question
Draw the substitution and elimination products for the following reactions, showing the configuration of each product:
b. cis-1-chloro-2-methylcyclohexane + CH3O−
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Textbook Question
Which reacts faster in an E1 reaction?
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Textbook Question
Draw the substitution and elimination products for the following reactions, showing the configuration of each product:
a. trans-1-chloro-2-methylcyclohexane + CH3O−
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