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

Equatorial Preference

Organic Chemistry

4. Alkanes and Cycloalkanes

Equatorial Preference

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3:58 minutes

Problem 68

Textbook Question

Which of the following conformers has the highest energy (is the least stable)?

Verified step by step guidance

Identify the different conformers presented in the image. Conformers are different spatial arrangements of a molecule that result from rotation around a single bond.

Understand that the energy of a conformer is influenced by steric strain, torsional strain, and angle strain. Steric strain occurs when atoms are forced too close to each other, torsional strain arises from eclipsing interactions, and angle strain is due to bond angles deviating from their ideal values.

Examine each conformer for steric interactions. Look for large groups that are close to each other, as these will increase steric strain and thus the energy of the conformer.

Check for torsional strain by identifying eclipsed conformations. Eclipsed conformations have higher energy compared to staggered conformations due to increased torsional strain.

Compare the identified strains in each conformer to determine which has the highest energy. The conformer with the most steric and torsional strain will be the least stable and thus have the highest energy.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Conformational Analysis

Conformational analysis is the study of the different spatial arrangements of atoms in a molecule that can be interconverted by rotation around single bonds. These arrangements, known as conformers, can have varying degrees of stability based on steric interactions and torsional strain. Understanding conformational analysis is essential for predicting the most stable conformer and identifying which conformer has the highest energy.

Steric Strain

Steric strain occurs when atoms are forced closer together than their natural bond lengths, leading to increased repulsion between electron clouds. In conformers, steric strain can significantly affect stability; conformers with bulky groups in close proximity tend to be less stable due to this strain. Recognizing the impact of steric strain helps in determining which conformer is the least stable.

Torsional Strain

Torsional strain arises from the eclipsing interactions between atoms or groups in a molecule when they are aligned in a way that maximizes repulsion. This strain is particularly relevant in conformers where bonds are rotated into eclipsed positions, leading to higher energy states. Understanding torsional strain is crucial for evaluating the stability of different conformers and identifying the one with the highest energy.

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