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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2:57 minutes

Problem 53a

Textbook Question

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

Verified step by step guidance

Step 1: Understand the structure of the compound. The given compound is 2-methyl-2,4-hexadiene. This means the parent chain is hexane (6 carbons), with two double bonds at positions 2 and 4, and a methyl group attached to carbon 2.

Step 2: Identify the possibility of geometric isomerism. Geometric isomerism (cis/trans or E/Z) occurs when there is restricted rotation around a double bond and different groups attached to the carbons of the double bond. Analyze the substituents on the carbons involved in the double bonds at positions 2 and 4.

Step 3: Draw the possible geometric isomers for the double bond at position 2. For the double bond at position 2, consider the groups attached to the carbons: Carbon 2 has a methyl group and a hydrogen, while Carbon 3 has a hydrogen and the rest of the chain. Draw both the cis (same side) and trans (opposite side) configurations.

Step 4: Draw the possible geometric isomers for the double bond at position 4. For the double bond at position 4, Carbon 4 has a hydrogen and the rest of the chain, while Carbon 5 has a hydrogen and a methyl group. Again, draw both the cis and trans configurations for this double bond.

Step 5: Combine the configurations. Since there are two double bonds, each with two possible configurations, there are four possible geometric isomers in total. Name each isomer using the E/Z nomenclature, which is based on the Cahn-Ingold-Prelog priority rules, to describe the configuration of each double bond.

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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 in compounds with restricted rotation around a double bond or a ring structure. In alkenes, this isomerism arises when two different substituents are attached to each carbon of the double bond, leading to distinct spatial arrangements. The 'cis' isomer has similar groups on the same side, while the 'trans' isomer has them on opposite sides, affecting the compound's physical and chemical properties.

Double Bonds and Hybridization

Double bonds consist of one sigma bond and one pi bond, resulting from the overlap of p orbitals. In alkenes, such as 2-methyl-2,4-hexadiene, the presence of double bonds influences the molecule's geometry and hybridization. The carbon atoms involved in the double bond are typically sp² hybridized, leading to a planar structure around the double bond, which is crucial for determining possible geometric isomers.

Naming Isomers

The IUPAC naming system provides a standardized method for naming organic compounds, including geometric isomers. For alkenes, the position of the double bond and the arrangement of substituents must be indicated in the name. In the case of 2-methyl-2,4-hexadiene, the name reflects the location of the double bonds and the presence of the methyl group, which is essential for accurately identifying and distinguishing between the geometric isomers.

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