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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5:43 minutes

Problem 18a

Textbook Question

For the compound 1-ethyl-3-isopropylcyclopentane,

(a) draw two different cis and two different trans isomers.

Verified step by step guidance

Step 1: Understand the structure of the compound. The base structure is cyclopentane, a five-membered ring. The substituents are 1-ethyl and 3-isopropyl groups. The numbering starts at the ethyl group, ensuring the substituents are at positions 1 and 3.

Step 2: Recall the concept of cis and trans isomers. Cis isomers have both substituents on the same side of the ring plane, while trans isomers have substituents on opposite sides of the ring plane.

Step 3: Draw the first cis isomer. Place the ethyl group at position 1 and the isopropyl group at position 3, both pointing above the plane of the cyclopentane ring.

Step 4: Draw the second cis isomer. Place the ethyl group at position 1 and the isopropyl group at position 3, both pointing below the plane of the cyclopentane ring.

Step 5: Draw the two trans isomers. For the first trans isomer, place the ethyl group above the plane at position 1 and the isopropyl group below the plane at position 3. For the second trans isomer, reverse the positions: place the ethyl group below the plane at position 1 and the isopropyl group above the plane at position 3.

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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 compounds with restricted rotation around a double bond or a ring structure. In cis isomers, substituents are on the same side of the double bond or ring, while in trans isomers, they are on opposite sides. This spatial arrangement can significantly affect the physical and chemical properties of the compounds.

Cycloalkanes

Cycloalkanes are saturated hydrocarbons that contain carbon atoms arranged in a ring structure. The presence of rings introduces unique steric interactions and can lead to different isomeric forms, such as cis and trans isomers. Understanding the structure of cycloalkanes is essential for visualizing and drawing their isomers accurately.

Substituent Positioning

In organic chemistry, the positioning of substituents on a cycloalkane affects the compound's isomerism. For 1-ethyl-3-isopropylcyclopentane, the ethyl and isopropyl groups can be arranged in different orientations, leading to distinct cis and trans isomers. Recognizing how substituents interact within the ring is crucial for drawing and identifying these isomers.

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Related Practice

Textbook Question

Name the following:

Textbook Question

Draw the condensed structure for each of the following:

a. (Z)-1,3,5-tribromo-2-pentene

b. (Z)-3-methyl-2-heptene

c. (E)-1,2-dibromo-3-isopropyl-2-hexene

Textbook Question

Identify the following substituted cycloalkanes as cis or trans.

(a)

Textbook Question

Identify the following substituted cycloalkanes as cis or trans.

(c)

Textbook Question

Draw and name all stereoisomers of 3-chlorohepta-2,4-diene

b. using the E-Z nomenclature.

Textbook Question

Some of the following examples can show geometric isomerism, and some cannot. For the ones that can, draw all the geometric isomers, and assign complete names using the E-Z system.

c. 3-bromo-2-methylhex-3-ene

d. penta-1,3-diene

Textbook Question

Some of the following examples can show geometric isomerism, and some cannot. For the ones that can, draw all the geometric isomers, and assign complete names using the E-Z system.

a. 3-bromo-2-chloropent-2-ene

b. 3-ethylhexa-2,4-diene

Textbook Question

Label each structure as Z, E, or neither.

(a)

(b)

(c)

(d)

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