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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5:29 minutes

Problem 8c,d

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

Verified step by step guidance

Step 1: Understand geometric isomerism. Geometric isomerism occurs due to restricted rotation around a double bond, leading to different spatial arrangements of substituents. The E-Z system is used to describe these arrangements based on the priority of groups attached to the double bond.

Step 2: Analyze compound c, 3-bromo-2-methylhex-3-ene. Identify the double bond at the 3rd position. Check if the substituents on each carbon of the double bond are different, which is necessary for geometric isomerism.

Step 3: For compound c, assign priorities to the substituents on each carbon of the double bond using Cahn-Ingold-Prelog rules. The higher atomic number gets higher priority. Draw the possible isomers based on these priorities and label them as E or Z.

Step 4: Analyze compound d, penta-1,3-diene. Note that it has two double bonds. Check each double bond for different substituents on each carbon to determine if geometric isomerism is possible.

Step 5: For compound d, if geometric isomerism is possible, assign priorities to the substituents on each carbon of the double bonds using Cahn-Ingold-Prelog rules. Draw the possible isomers and label them using the E-Z system.

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Key Concepts

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

Geometric Isomerism

Geometric isomerism, also known as cis-trans isomerism, occurs due to restricted rotation around a double bond, leading to different spatial arrangements of substituents. In alkenes, this isomerism is possible when each carbon of the double bond has two different groups attached, allowing for distinct configurations.

E-Z Nomenclature

The E-Z system is a method for naming geometric isomers based on the priority of substituents attached to the double-bonded carbons. 'E' (from German 'entgegen') indicates opposite sides, while 'Z' (from German 'zusammen') indicates the same side. Priorities are determined using Cahn-Ingold-Prelog rules, considering atomic number and connectivity.

Double Bond Position and Substituents

The position of the double bond and the nature of substituents are crucial for determining geometric isomerism. In 3-bromo-2-methylhex-3-ene, the double bond at position 3 with different groups allows for isomerism. In penta-1,3-diene, the presence of two double bonds requires analysis of each for potential isomerism, considering substituent arrangement.

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Related Practice

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

For the compound 1-ethyl-3-isopropylcyclopentane,

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

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.

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)

Textbook Question

1. Determine which of the following compounds show cis-trans isomerism.

2. Draw and name the cis and trans (or Z and E) isomers of those that do.

e. 2,3-dimethylpent-2-ene