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

5. Chirality

Constitutional Isomers vs. Stereoisomers

Organic Chemistry

5. Chirality

Constitutional Isomers vs. Stereoisomers

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1:49 minutes

Problem 66c

Textbook Question

How many stereoisomers are possible for the following alkenes?
(c)

Verified step by step guidance

Step 1: Identify the stereogenic centers in the molecule. A stereogenic center is an atom (usually carbon) bonded to four different groups. In the given structure, the carbon attached to the hydroxyl group (-OH) is a stereogenic center because it is bonded to four distinct groups.

Step 2: Determine the number of double bonds in the molecule that can exhibit cis-trans (E/Z) isomerism. Double bonds can show stereoisomerism if each carbon in the double bond is attached to two different groups. In the given structure, there are two double bonds that can exhibit E/Z isomerism.

Step 3: Calculate the total number of stereoisomers using the formula: Total stereoisomers = 2^n, where n is the number of stereogenic centers and stereoisomeric double bonds. In this case, there is 1 stereogenic center and 2 stereoisomeric double bonds, so n = 3.

Step 4: Apply the formula to calculate the total number of stereoisomers. Since n = 3, the total number of stereoisomers is 2^3 = 8.

Step 5: Verify the structure to ensure no additional stereogenic centers or stereoisomeric double bonds are overlooked. Confirm that the molecule has 1 stereogenic center and 2 stereoisomeric double bonds, leading to 8 possible stereoisomers.

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Key Concepts

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

Stereoisomerism

Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. This can lead to different physical and chemical properties. In alkenes, stereoisomers arise due to the restricted rotation around the double bond, resulting in cis and trans configurations.

Chirality

Chirality is a property of a molecule that makes it non-superimposable on its mirror image, often due to the presence of a chiral center, typically a carbon atom bonded to four different substituents. In the context of alkenes, if a double bond is attached to two different groups on each carbon, it can lead to the formation of enantiomers, which are a type of stereoisomer.

Counting Stereoisomers

The number of possible stereoisomers for a compound can be determined using the formula 2^n, where n is the number of chiral centers in the molecule. Additionally, for alkenes with restricted rotation, the presence of different substituents on the double bond can also contribute to the total count of stereoisomers, including both geometric (cis/trans) and optical isomers.

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Related Practice

Textbook Question

For the compound 1-ethyl-3-isopropylcyclopentane,

(b) What is the stereochemical relationship between the cis isomers?

Textbook Question

(a) Give the products expected when (+)@glyceraldehyde reacts with HCN.(b) What is the relationship between the products? How might they be separated?(c) Are the products optically active? Explain.

Textbook Question

(a) Give the products expected when (+)-glyceraldehyde reacts with HCN.

(b) What is the relationship between the products? How might they be separated?

Textbook Question

For the compound 1-ethyl-3-isopropylcyclopentane,

(d) LOOKING AHEAD What is the relationship between a cis isomer and a trans isomer?

Textbook Question

b. Draw the six stereoisomers of octa-2,4,6-triene. Explain why there are only six stereoisomers, rather than the eight we might expect for a compound with three stereogenic double bonds.

Textbook Question

Draw the six stereoisomers of octa-2,4,6-triene. Explain why there are only six stereoisomers, rather than the eight we might expect for a compound with three stereogenic double bonds.

Textbook Question

For each pair, give the relationship between the two compounds. Making models will be helpful.

(c)

(d)

Textbook Question

Which of the following pairs of compounds could be separated by recrystallization or distillation?b. and

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