Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

4. Alkanes and Cycloalkanes

Axial vs Equatorial

Organic Chemistry

4. Alkanes and Cycloalkanes

Axial vs Equatorial

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6:16 minutes

Problem 51c,d

Textbook Question

For each of the following disubstituted cyclohexanes, indicate whether the substituents in the two chair conformers are both equatorial in one chair conformer and both axial in the other or one equatorial and one axial in each of the chair conformers:
c. cis-1,3-
d. trans-1,3-

Verified step by step guidance

Step 1: Understand the problem. We are tasked with analyzing the chair conformations of disubstituted cyclohexanes (cis-1,3- and trans-1,3-) to determine the positions of the substituents (axial or equatorial) in each conformer.

Step 2: Recall the key concepts. In a cyclohexane chair conformation, substituents can occupy either axial (perpendicular to the ring plane) or equatorial (roughly parallel to the ring plane) positions. The relative positions of substituents (cis or trans) determine their placement in the chair conformers.

Step 3: Analyze the cis-1,3-disubstituted cyclohexane. For cis-1,3-, the two substituents are on the same side of the ring. In one chair conformer, one substituent will be axial, and the other will be equatorial. When the chair flips, the positions will switch, so the other substituent becomes axial, and the first becomes equatorial. Thus, in both conformers, one substituent is axial, and the other is equatorial.

Step 4: Analyze the trans-1,3-disubstituted cyclohexane. For trans-1,3-, the two substituents are on opposite sides of the ring. In one chair conformer, both substituents will occupy equatorial positions. When the chair flips, both substituents will occupy axial positions. Thus, in one conformer, both are equatorial, and in the other, both are axial.

Step 5: Summarize the findings. For cis-1,3-, the substituents are one axial and one equatorial in each conformer. For trans-1,3-, the substituents are both equatorial in one conformer and both axial in the other.

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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, allowing for minimized steric strain. In this conformation, carbon atoms are arranged in a staggered manner, which provides two types of positions for substituents: axial (pointing up or down) and equatorial (pointing outward). Understanding chair conformations is crucial for analyzing the spatial arrangement of substituents in disubstituted cyclohexanes.

Cis and Trans Isomerism

Cis and trans isomerism refers to the orientation of substituents around a ring or double bond. In cyclohexanes, 'cis' indicates that substituents are on the same side of the ring, while 'trans' indicates they are on opposite sides. This distinction affects the stability and conformational preferences of the molecule, influencing whether substituents can be both equatorial or axial in chair conformations.

Axial and Equatorial Positions

In cyclohexane chair conformations, substituents can occupy axial or equatorial positions, which significantly impacts steric interactions. Axial substituents are aligned parallel to the axis of the ring, leading to potential 1,3-diaxial interactions that increase steric strain. Conversely, equatorial substituents extend outward, reducing steric hindrance and generally leading to a more stable conformation. Understanding these positions is essential for predicting the stability of disubstituted cyclohexanes.

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