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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3:14 minutes

Problem 7b

Textbook Question

Draw Fischer projections of the following molecules.
(b)

Verified step by step guidance

Understand the Fischer projection: A Fischer projection is a two-dimensional representation of a molecule where the vertical lines represent bonds going away from the viewer (into the plane), and the horizontal lines represent bonds coming toward the viewer (out of the plane). The carbon chain is arranged vertically, with the most oxidized carbon (e.g., a carbonyl group) at the top.

Identify the stereocenters in the molecule: Look for carbons that are bonded to four different groups. These are the chiral centers that will determine the stereochemistry of the Fischer projection.

Assign the configuration (R or S) to each stereocenter: Use the Cahn-Ingold-Prelog priority rules to assign priorities to the groups attached to each stereocenter. Then, determine the configuration based on the arrangement of these groups.

Draw the Fischer projection: Place the most oxidized carbon (e.g., aldehyde or ketone group) at the top of the vertical line. Arrange the substituents on the horizontal and vertical lines according to the stereochemistry determined in the previous step. Ensure that the horizontal substituents are coming out of the plane and the vertical substituents are going into the plane.

Double-check the stereochemistry: Verify that the Fischer projection correctly represents the stereochemistry of the molecule by mentally converting it back to a three-dimensional structure and confirming the configurations of the stereocenters.

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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 it determines the orientation of the substituents in the projection.

Stereochemistry

Stereochemistry is the study of the spatial arrangement of atoms in molecules and how this arrangement affects their chemical properties and reactions. It encompasses concepts such as enantiomers, diastereomers, and geometric isomers. In the context of Fischer projections, stereochemistry is vital for correctly representing the 3D orientation of substituents around chiral centers, which influences the molecule's behavior in biological systems.

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