Textbook Question
Draw 1,2,3,4,5,6-hexamethylcyclohexane with all the methyl groups
a. in axial positions.
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Ch.3 - Structure and Stereochemistry of Alkanes
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 3, Problem 22b
Draw 1,2,3,4,5,6-hexamethylcyclohexane with all the methyl groups
b. in equatorial positions.
Verified step by step guidance1
Start by drawing the basic structure of cyclohexane in its chair conformation. This is the most stable conformation of cyclohexane, where alternating carbon atoms are positioned above and below the plane of the ring.
Label the six carbon atoms in the cyclohexane ring (C1 through C6) to keep track of the positions where the substituents (methyl groups) will be added.
Recall that in the chair conformation, each carbon atom has two substituent positions: one axial (pointing straight up or down) and one equatorial (pointing outward and slightly angled). For this problem, all methyl groups need to be placed in equatorial positions.
Add a methyl group (-CH₃) to each carbon atom (C1 through C6) in the equatorial position. Ensure that the equatorial positions alternate directions around the ring to maintain the correct geometry of the chair conformation.
Double-check your drawing to confirm that all six methyl groups are in equatorial positions and that the chair conformation is correctly represented. This ensures the structure is accurate and adheres to the problem's requirements.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cyclohexane Conformation
Cyclohexane can adopt different conformations, primarily chair and boat forms. The chair conformation is the most stable due to minimized steric strain and torsional strain. Understanding these conformations is crucial for visualizing how substituents, like methyl groups, are positioned on the ring.
Recommended video:
Guided course
03:29
Understanding what a conformer is.
Equatorial vs. Axial Positions
In the chair conformation of cyclohexane, substituents can occupy either equatorial or axial positions. Equatorial positions extend outward from the ring, reducing steric hindrance, while axial positions point up or down, potentially causing 1,3-diaxial interactions. For stability, bulky groups prefer equatorial positions.
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Guided course
04:02Equatorial Preference
Substituent Effects on Stability
The placement of substituents on cyclohexane affects the overall stability of the molecule. In the case of 1,2,3,4,5,6-hexamethylcyclohexane, having all six methyl groups in equatorial positions minimizes steric interactions, leading to a more stable structure compared to having any in axial positions.
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2:02Directing Effects in Substituted Pyrroles, Furans, and Thiophenes Concept 1
Related Practice
Textbook Question
Draw the most stable conformation of
a. ethylcyclohexane.
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Textbook Question
Table 3-6 shows that the axial–equatorial energy difference for methyl, ethyl, and isopropyl groups increases gradually: 7.6, 7.9, and 8.8 kJ/mol (1.8, 1.9, and 2.1 kcal/mol). The tert-butyl group jumps to an energy difference of 23 kJ/mol (5.4 kcal/mol), over twice the value for the isopropyl group. Draw pictures of the axial conformations of isopropylcyclohexane and tert-butylcyclohexane, and explain why the tert-butyl substituent experiences such a large increase in axial energy over the isopropyl group.
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Textbook Question
trans-1,2-Dimethylcyclobutane is more stable than cis-1,2-dimethylcyclobutane, but cis-1,3-dimethylcyclobutane is more stable than trans-1,3-dimethylcyclobutane. Use drawings to explain these observations.
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Textbook Question
Draw a Newman projection, similar to Figure 3-25 down the C1—C6 bond in the equatorial conformation of methylcyclohexane. Show that the equatorial methyl group is also anti to C5. (Using your models will help.)
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Textbook Question
The cyclohexane chair shown in Figure 3-22 has the headrest to the right and the footrest to the left. Draw a cyclohexane chair with its axial and equatorial bonds, showing the headrest to the left and the footrest to the right.
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