Textbook Question
What is the configuration of each of the asymmetric centers in the following compounds?
c.
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Ch. 4 - Isomers: The Arrangement of Atoms in Space
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 5, Problem 102a
Draw the two chair conformers for each of the stereoisomers of trans-1-tert-butyl-3-methylcyclohexane.
Verified step by step guidance1
Step 1: Begin by understanding the structure of cyclohexane and its chair conformations. Cyclohexane can adopt two chair conformations, which are interconvertible. In this problem, we are dealing with trans-1-tert-butyl-3-methylcyclohexane, meaning the substituents (tert-butyl and methyl groups) are on opposite sides of the ring (one axial and one equatorial).
Step 2: Identify the positions of the substituents on the cyclohexane ring. The tert-butyl group is at position 1, and the methyl group is at position 3. Since the molecule is trans, one substituent will be in the axial position, and the other will be in the equatorial position in each chair conformer.
Step 3: Draw the first chair conformer. Start by placing the cyclohexane ring in a chair conformation. Assign the tert-butyl group at position 1 to the axial position (upward) and the methyl group at position 3 to the equatorial position (downward). Ensure the substituents are on opposite sides of the ring to reflect the trans configuration.
Step 4: Draw the second chair conformer. Flip the chair conformation by interchanging axial and equatorial positions. In this conformer, the tert-butyl group at position 1 will now occupy the equatorial position (downward), and the methyl group at position 3 will occupy the axial position (upward). Again, confirm that the substituents remain trans to each other.
Step 5: Compare the stability of the two chair conformers. The tert-butyl group is bulky, and it prefers the equatorial position to minimize steric hindrance. Therefore, the conformer with the tert-butyl group in the equatorial position is likely to be more stable. This analysis helps in understanding the preferred conformation of the molecule.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Chair Conformation
Chair conformation is the most stable form of cyclohexane, characterized by a three-dimensional arrangement that minimizes steric strain and torsional strain. In this conformation, carbon atoms alternate between axial and equatorial positions, allowing for optimal spatial distribution of substituents. Understanding chair conformations is crucial for analyzing the stability and reactivity of cyclohexane derivatives.
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03:29
Understanding what a conformer is.
Stereoisomers
Stereoisomers are compounds that have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. In the case of trans-1-tert-butyl-3-methylcyclohexane, the term 'trans' indicates that the bulky tert-butyl and methyl groups are positioned on opposite sides of the cyclohexane ring. Recognizing stereoisomers is essential for predicting the physical and chemical properties of organic compounds.
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01:58Determining when molecules are stereoisomers.
Axial and Equatorial Positions
In cyclohexane chair conformations, substituents can occupy either axial or equatorial positions. Axial substituents are oriented parallel to the axis of the ring, while equatorial substituents extend outward from the ring, reducing steric hindrance. The preference for substituents to occupy equatorial positions is a key factor in determining the stability of different conformers, especially in substituted cyclohexanes.
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Related Practice
Textbook Question
A student decided that the configuration of the asymmetric centers in a sugar such as D-glucose could be determined rapidly by simply assigning the R configuration to an symmetric center with an OH group on the right and the S configuration to an symmetric center with an OH group on the left. Is he correct?
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Textbook Question
What is the configuration of each of the asymmetric centers in the following compounds?
a.
b.
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Textbook Question
What is the configuration of each of the asymmetric centers in the following compounds?
c.
d.
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Textbook Question
Tamiflu is used for the prevention and treatment of flu. What is the configuration of each of its asymmetric centers?
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Textbook Question
For each pair, indicate which conformer is more stable.
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