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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6:45 minutes

Problem 53d

Textbook Question

For each of the following compounds, draw the possible geometric isomers and name each isomer:
d. 3-methyl-2,4-hexadiene

Verified step by step guidance

Step 1: Understand the structure of 3-methyl-2,4-hexadiene. The compound is a diene, meaning it contains two double bonds. The parent chain is hexadiene (a six-carbon chain with two double bonds), and there is a methyl group attached to the third carbon.

Step 2: Identify the positions of the double bonds. The double bonds are located at carbons 2 and 4. Each double bond can exhibit geometric (cis/trans or E/Z) isomerism because the carbons involved in the double bonds have different substituents.

Step 3: Analyze the substituents around each double bond. For the double bond at carbon 2, the substituents are: (a) a hydrogen atom and (b) the rest of the chain (C3-C6). For the double bond at carbon 4, the substituents are: (a) a hydrogen atom and (b) the rest of the chain (C5-C6).

Step 4: Draw all possible geometric isomers. For each double bond, determine whether the substituents are on the same side (cis or Z) or opposite sides (trans or E). Combine the configurations of both double bonds to generate all possible isomers. For example, you could have (Z,Z), (Z,E), (E,Z), and (E,E) configurations.

Step 5: Name each isomer using the E/Z nomenclature. Assign priorities to the substituents on each double bond using the Cahn-Ingold-Prelog priority rules. Based on the relative positions of the higher-priority groups, assign E (opposite sides) or Z (same side) to each double bond and name the compound accordingly (e.g., (2E,4Z)-3-methyl-2,4-hexadiene).

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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 occurs due to the restricted rotation around double bonds or ring structures, leading to different spatial arrangements of atoms. In alkenes, this is often classified into cis and trans isomers, where 'cis' indicates that substituents are on the same side of the double bond, while 'trans' indicates they are on opposite sides. Understanding this concept is crucial for identifying and drawing the correct isomers of compounds like 3-methyl-2,4-hexadiene.

Alkene Nomenclature

Alkene nomenclature follows specific rules set by the IUPAC system, which includes identifying the longest carbon chain containing the double bond and numbering it to give the lowest possible numbers to the double bond. For 3-methyl-2,4-hexadiene, the name indicates the presence of a double bond between the second and third carbons and another between the fourth and fifth carbons, along with a methyl group on the third carbon. This understanding is essential for accurately naming the geometric isomers.

Stereochemistry

Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the context of geometric isomers, it helps in understanding how different arrangements can lead to distinct physical and chemical properties. For 3-methyl-2,4-hexadiene, recognizing the stereochemical implications of the double bonds is vital for drawing and naming the correct isomers, as the arrangement of substituents can significantly influence the compound's characteristics.

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