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

Cis vs Trans

Organic Chemistry

4. Alkanes and Cycloalkanes

Cis vs Trans

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5:51 minutes

Problem 3a

Textbook Question

a. Which of the following compounds can exist as cis–trans isomers?

Verified step by step guidance

Step 1: Understand the concept of cis-trans isomerism. Cis-trans isomerism occurs in compounds with restricted rotation around a double bond, typically due to the presence of a π-bond. For cis-trans isomerism to exist, the two groups attached to each carbon of the double bond must be different.

Step 2: Analyze compound 1 (CH3CH=CHCH2CH2CH3). Check the groups attached to each carbon of the double bond. The first carbon has CH3 and H, and the second carbon has CH2CH2CH3 and H. Since both carbons have two different groups, this compound can exist as cis-trans isomers.

Step 3: Analyze compound 2 (CH3CH=CHCH3). Check the groups attached to each carbon of the double bond. The first carbon has CH3 and H, and the second carbon also has CH3 and H. Since the groups attached to the second carbon are identical, this compound cannot exist as cis-trans isomers.

Step 4: Analyze compound 3 (CH3CH2C(CH2CH3)=CHCH3). Check the groups attached to each carbon of the double bond. The first carbon has CH3CH2 and CH2CH3, and the second carbon has CH3 and H. Since both carbons have two different groups, this compound can exist as cis-trans isomers.

Step 5: Analyze compound 4 (CH3CH2CH=CH2). Check the groups attached to each carbon of the double bond. The first carbon has CH3CH2 and H, and the second carbon has H and H. Since the second carbon has identical groups, this compound cannot exist as cis-trans isomers.

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Key Concepts

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

Cis-Trans Isomerism

Cis-trans isomerism, also known as geometric isomerism, occurs in alkenes where the arrangement of substituents around a double bond can differ. In cis isomers, similar groups are on the same side of the double bond, while in trans isomers, they are on opposite sides. This difference in spatial arrangement can lead to distinct physical and chemical properties.

Alkenes and Double Bonds

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond (C=C). The presence of this double bond restricts rotation, allowing for the possibility of cis-trans isomerism. The ability to form isomers depends on having two different substituents on each carbon of the double bond.

Substituent Diversity

For a compound to exhibit cis-trans isomerism, each carbon atom involved in the double bond must have two different substituents. If both substituents on a carbon are the same, the compound cannot have cis-trans isomers. Evaluating the substituents on the double bond is crucial for determining the existence of these isomers.

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