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

Fischer Projection

Organic Chemistry

5. Chirality

Fischer Projection

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4:09 minutes

Problem 16c

Textbook Question

For each set of examples, make a model of the first structure, and indicate the relationship of each of the other structures to the first structure. Examples of relationships: same compound, enantiomer, structural isomer.
(c)

Verified step by step guidance

Step 1: Begin by analyzing the first structure, which is labeled as (R)-butan-2-ol. This structure has a chiral center at the second carbon atom, with the following substituents: a hydroxyl group (-OH), a methyl group (-CH3), an ethyl group (-CH2CH3), and a hydrogen atom (H). The (R) configuration indicates the absolute stereochemistry based on the Cahn-Ingold-Prelog priority rules.

Step 2: Compare the second structure to the first structure. Notice that the positions of the substituents around the chiral center are inverted. This inversion of substituents indicates that the second structure is the enantiomer of the first structure, specifically the (S)-butan-2-ol.

Step 3: Compare the third structure to the first structure. Observe that the hydroxyl group (-OH) and the hydrogen atom (H) have swapped positions, but the methyl group (-CH3) and ethyl group (-CH2CH3) remain in the same positions. This inversion of two substituents around the chiral center also results in the enantiomer of the first structure, which is again (S)-butan-2-ol.

Step 4: Compare the fourth structure to the first structure. Notice that the arrangement of substituents around the chiral center is identical to the first structure. This indicates that the fourth structure is the same compound as the first structure, (R)-butan-2-ol.

Step 5: Summarize the relationships: The second and third structures are enantiomers of the first structure, while the fourth structure is the same compound as the first structure.

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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 includes enantiomers, which are non-superimposable mirror images of each other, and diastereomers, which are not mirror images. Understanding stereoisomerism is crucial for analyzing the relationships between different structures, such as those shown in the provided image.

Structural Isomers

Structural isomers are compounds that have the same molecular formula but differ in the connectivity of their atoms. This can lead to different functional groups or arrangements, resulting in distinct chemical properties. In the context of the question, recognizing structural isomers is essential for identifying how the given structures relate to (R)-butan-2-ol, as they may share the same formula but differ in structure.

Chirality

Chirality is a property of a molecule that makes it non-superimposable on its mirror image, much like left and right hands. A chiral center, often a carbon atom bonded to four different groups, is responsible for this property. In the case of (R)-butan-2-ol, its chirality leads to the existence of enantiomers, which are critical for understanding the relationships depicted in the image, as they can exhibit different optical activities.

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Related Practice

Textbook Question

Draw Fischer projections of the following molecules.

(c)

Textbook Question

Convert the following perspective formulas to Fischer projections.

(c)

(d)

Textbook Question

Convert the following Fischer projections to perspective formulas

(c)

(d)

Textbook Question

(a) There is only one ketotriose, called dihydroxyacetone. Draw its structure.

(b) There is only one aldotriose, called glyceraldehyde. Draw the two enantiomers of glyceraldehyde.

Textbook Question

Which of the following compounds are chiral? Draw each compound in its most symmetric conformation, star (*) any asymmetric carbon atoms, and draw any mirror planes. Label any meso compounds. You may use Fischer projections if you prefer.

(e) (R,R)-2,3-dibromobutane

(f)

Textbook Question

Draw a Fischer projection for each compound. Remember that the cross represents an asymmetric carbon atom, and the carbon chain should be along the vertical, with the IUPAC numbering from top to bottom.

(e)

Textbook Question

a. Are d-erythrose and l-erythrose enantiomers or diastereomers?

b. Are l-erythrose and l-threose enantiomers or diastereomers?

Textbook Question

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

(e)

(f)

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