Textbook Question
Draw the two chair conformers for each of the following and indicate which conformer is more stable:
d. cis-1,2-diethylcyclohexane
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Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure
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. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and StructureProblem 74f
Bruice 8th EditionCh. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and StructureProblem 74fChapter 4, Problem 74f
Draw the two chair conformers for each of the following and indicate which conformer is more stable:
f. cis-1-ethyl-4-isopropylcyclohexane
Verified step by step guidance1
Step 1: Understand the structure of cis-1-ethyl-4-isopropylcyclohexane. The 'cis' designation means that both substituents (ethyl and isopropyl groups) are on the same side of the cyclohexane ring. This will be important when placing the groups in the chair conformations.
Step 2: Draw the basic chair conformation of cyclohexane. Label the carbon atoms in the ring to help with substituent placement. For example, assign carbon-1 to the position where the ethyl group is attached and carbon-4 to the position where the isopropyl group is attached.
Step 3: Place the substituents on the chair conformation. Since the substituents are 'cis,' both groups must either be in axial positions or both in equatorial positions. Draw one conformer with both substituents in axial positions and another conformer with both substituents in equatorial positions.
Step 4: Evaluate the stability of each conformer. Recall that larger groups prefer the equatorial position due to reduced steric hindrance. Compare the steric interactions in the axial positions versus the equatorial positions for both the ethyl and isopropyl groups.
Step 5: Conclude which conformer is more stable. The conformer with both substituents in equatorial positions will generally be more stable because it minimizes steric hindrance between the bulky groups and the axial hydrogens on the ring.
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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 a three-dimensional representation of cyclohexane that minimizes steric strain and torsional strain. In this conformation, the carbon atoms are arranged in a staggered manner, allowing for more stable interactions between substituents. Understanding chair conformations is crucial for analyzing the stability of cyclohexane derivatives, as different substituents can occupy axial or equatorial positions, affecting overall stability.
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Understanding what a conformer is.
Cis and Trans Isomerism
Cis and trans isomerism refers to the spatial arrangement of substituents around a ring or double bond. In the context of cyclohexane, 'cis' indicates that substituents are on the same side of the ring, while 'trans' means they are on opposite sides. This arrangement significantly influences the steric interactions between substituents, which in turn affects the stability of the conformers, making it essential to identify the correct isomer when analyzing stability.
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Steric Hindrance
Steric hindrance is the repulsion between atoms that occurs when they are brought close together, often due to the size of substituents. In cyclohexane derivatives, larger groups prefer equatorial positions to minimize steric interactions with other substituents. Recognizing which conformer has less steric hindrance is key to determining which chair conformation is more stable, as lower steric strain typically correlates with greater stability.
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Related Practice
Textbook Question
Draw the two chair conformers for each of the following and indicate which conformer is more stable:
c. trans-1-ethyl-2-isopropylcyclohexane
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Textbook Question
Draw the two chair conformers for each of the following and indicate which conformer is more stable:
e. cis-1-ethyl-3-isopropylcyclohexane
670
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Textbook Question
Draw the conformer that is present in greatest concentration.
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Textbook Question
Draw a potential energy diagram for rotation about the C¬C bond of 1,2-dichloroethane through 360°, starting with the least stable conformer. The anti conformer is 1.2 kcal/mol more stable than a gauche conformer. A gauche conformer has two energy barriers, 5.2 kcal/mol and 9.3 kcal/mol.
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Textbook Question
Why are lower molecular weight alcohols more soluble in water than higher molecular weight alcohols?
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