Textbook Question
What is the major product formed when the following compounds undergo an E1 reaction?
c.
2
views
Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
Not the one you use?Change textbookSelect a different textbook
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
All textbooks
Bruice 8th EditionCh. 9 - Substitution and Elimination Reactions of Alkyl HalidesProblem 37
Bruice 8th EditionCh. 9 - Substitution and Elimination Reactions of Alkyl HalidesProblem 37Chapter 10, Problem 37
Which isomer reacts more rapidly in an E2 reaction: cis-1-bromo-4-tert-butylcyclohexane or trans-1-bromo-4-tert-butylcyclohexane? Explain your answer.
Verified step by step guidance1
Understand the E2 reaction mechanism: E2 reactions are bimolecular elimination reactions where a base removes a proton from the β-carbon, and the leaving group departs simultaneously, forming a double bond.
Consider the stereochemistry of the cyclohexane ring: In cyclohexane, substituents can be in axial or equatorial positions. For an E2 reaction, the leaving group and the hydrogen being abstracted must be antiperiplanar, meaning they should be on opposite sides of the ring.
Analyze the cis isomer: In cis-1-bromo-4-tert-butylcyclohexane, the bromine and tert-butyl group are on the same side of the cyclohexane ring. This configuration may not allow the bromine to be antiperiplanar to a hydrogen on the adjacent carbon, making the E2 reaction less favorable.
Analyze the trans isomer: In trans-1-bromo-4-tert-butylcyclohexane, the bromine and tert-butyl group are on opposite sides of the cyclohexane ring. This configuration allows the bromine to be antiperiplanar to a hydrogen on the adjacent carbon, facilitating the E2 reaction.
Conclude which isomer reacts more rapidly: The trans isomer is more likely to have the correct antiperiplanar arrangement for the E2 reaction, making it react more rapidly compared to the cis isomer.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
6mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
E2 Reaction Mechanism
The E2 (bimolecular elimination) reaction is a concerted process where a base abstracts a proton while a leaving group departs, resulting in the formation of a double bond. The reaction rate depends on the concentration of both the substrate and the base. In cyclohexane derivatives, the stereochemistry of substituents can significantly influence the accessibility of the hydrogen atoms that are eliminated.
Recommended video:
Guided course
09:36
Drawing the E2 Mechanism.
Stereochemistry and Chair Conformation
Cyclohexane can adopt different chair conformations, which affect the spatial arrangement of substituents. In the case of cis and trans isomers, the positioning of bulky groups like tert-butyl can hinder or facilitate the approach of the base during the E2 reaction. The more accessible the hydrogen atoms are for elimination, the faster the reaction will proceed.
Recommended video:
1:38Polymer Stereochemistry Concept 1
Steric Hindrance
Steric hindrance refers to the repulsion between bulky groups that can impede reactions. In the context of the isomers in question, the bulky tert-butyl group in trans-1-bromo-4-tert-butylcyclohexane is positioned equatorially, allowing for better access to axial hydrogens for elimination. In contrast, the cis isomer may have more steric strain, leading to slower reaction rates.
Recommended video:
Guided course
02:53Understanding steric effects.
Related Practice
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
2
views
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−
1
views
Textbook Question
Why do cis-1-bromo-2-ethylcyclohexane and trans-1-bromo-2-ethylcyclohexane form different major products when they undergo an E2 reaction?
1
views
Textbook Question
What is the major product formed when the following compounds undergo an E1 reaction?
b.
2
views
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−
1
views