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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6:31 minutes

Problem 7a

Textbook Question

Draw Fischer projections of the following molecules.
(a)

Verified step by step guidance

Step 1: Understand the Fischer projection. A Fischer projection is a 2D representation of a 3D molecule, where horizontal lines represent bonds projecting out of the plane (toward the viewer), and vertical lines represent bonds projecting behind the plane (away from the viewer). The carbon chain is typically arranged vertically, with the most oxidized carbon (e.g., aldehyde or ketone group) at the top.

Step 2: Identify the stereocenters in the molecule. Stereocenters are carbon atoms bonded to four different groups. Determine the configuration (R or S) of each stereocenter using the Cahn-Ingold-Prelog priority rules.

Step 3: Arrange the molecule in a way that aligns with the Fischer projection convention. Place the main carbon chain vertically, ensuring the highest-priority functional group (e.g., aldehyde or ketone) is at the top. Rotate the molecule if necessary to achieve this orientation.

Step 4: Assign the substituents to the horizontal and vertical positions. The horizontal substituents should represent groups projecting out of the plane (toward the viewer), while the vertical substituents represent groups projecting behind the plane (away from the viewer). Ensure the stereochemistry is preserved during this process.

Step 5: Draw the Fischer projection based on the arrangement from Step 4. Double-check the stereochemistry to ensure the configuration matches the original molecule. If there are multiple stereocenters, repeat the process for each one.

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Key Concepts

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

Fischer Projections

Fischer projections are a two-dimensional representation of three-dimensional organic molecules, particularly useful for depicting carbohydrates and amino acids. In these projections, vertical lines represent bonds that extend away from the viewer, while horizontal lines indicate bonds that come towards the viewer. This format helps in visualizing stereochemistry and understanding the spatial arrangement of substituents around chiral centers.

Chirality

Chirality refers to the property of a molecule that has non-superimposable mirror images, much like left and right hands. Molecules that possess chirality typically have one or more chiral centers, usually carbon atoms bonded to four different substituents. Understanding chirality is crucial for accurately drawing Fischer projections, as the orientation of substituents determines the molecule's stereoisomerism.

Stereoisomers

Stereoisomers are compounds that have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of their atoms. This category includes enantiomers, which are mirror images of each other, and diastereomers, which are not. Recognizing the types of stereoisomers is essential when drawing Fischer projections, as it influences the representation of the molecule's structure and its biological activity.

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