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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Problem 8

Textbook Question

In this attempt to convert the line angle drawing of d-erythrose (shown) to the Fischer projection (shown), by viewing it from a certain direction (shown), a mistake was made. What was the mistake?
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Verified step by step guidance

Identify the structure of d-erythrose in the line-angle drawing and understand its stereochemistry. d-Erythrose is a four-carbon aldose sugar with two chiral centers, and its stereochemistry is defined by the 'd-' configuration, which refers to the orientation of the hydroxyl group on the highest-numbered chiral carbon in the Fischer projection.

Review the process of converting a line-angle drawing to a Fischer projection. This involves orienting the molecule such that the carbon chain is vertical, with the most oxidized carbon (the aldehyde group) at the top. The horizontal bonds in the Fischer projection represent groups coming out of the plane toward the viewer, while vertical bonds represent groups going behind the plane.

Examine the direction from which the molecule was viewed to create the Fischer projection. A common mistake occurs when the molecule is viewed from the wrong perspective, leading to an incorrect assignment of the stereochemistry of the chiral centers.

Compare the stereochemistry of the chiral centers in the Fischer projection with the original line-angle drawing. Verify whether the hydroxyl groups on the second and third carbons are correctly positioned (right or left) in the Fischer projection based on the original stereochemistry.

Determine the specific mistake made. If the Fischer projection does not match the stereochemistry of the line-angle drawing, the error likely lies in the perspective used to view the molecule or in the incorrect assignment of the horizontal and vertical bonds in the Fischer projection.

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Key Concepts

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

Line-Angle Drawings

Line-angle drawings are a simplified way to represent organic molecules, where lines represent bonds and vertices represent carbon atoms. This method allows chemists to visualize complex structures without drawing every atom explicitly. Understanding how to interpret these drawings is crucial for converting them into other representations, such as Fischer projections.

Fischer Projections

Fischer projections are a two-dimensional representation of three-dimensional organic molecules, particularly useful for depicting carbohydrates and amino acids. In this format, vertical lines represent bonds going behind the plane of the page, while horizontal lines represent bonds coming out of the page. Correctly converting a line-angle drawing to a Fischer projection requires careful attention to the orientation of substituents around the chiral centers.

Stereochemistry

Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In the context of converting structures, it is essential to maintain the correct stereochemical configuration, especially for chiral centers. A mistake in stereochemistry can lead to incorrect representations and misinterpretations of the molecule's properties and reactivity.

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