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

R and S of Fischer Projections

Organic Chemistry

5. Chirality

R and S of Fischer Projections

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5:49 minutes

Problem 23a,b

Textbook Question

What is the configuration of each of the following?
a.
b.

Verified step by step guidance

Step 1: Identify the chiral center in each molecule. A chiral center is a carbon atom bonded to four different groups. In both molecules (a and b), the central carbon atom is the chiral center.

Step 2: Assign priorities to the substituents attached to the chiral center based on the Cahn-Ingold-Prelog (CIP) priority rules. The priority is determined by the atomic number of the atoms directly attached to the chiral center. For molecule (a), the groups are OH, CH3, H, and CH2OH. For molecule (b), the groups are OH, CH2CH3, H, and CH2OH.

Step 3: Orient the molecule so that the lowest priority group (H) is pointing away from you. This is typically done by imagining the molecule in a 3D perspective or using a model.

Step 4: Determine the order of the remaining three groups (1, 2, 3) in a clockwise or counterclockwise direction. If the order is clockwise, the configuration is R. If the order is counterclockwise, the configuration is S.

Step 5: Repeat the process for both molecules (a and b) to determine their respective configurations. Ensure you carefully follow the CIP rules and visualize the molecule in 3D to assign the correct configuration.

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Key Concepts

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

Chirality

Chirality refers to the geometric property of a molecule that makes it non-superimposable on its mirror image. A chiral molecule typically has a carbon atom bonded to four different substituents, leading to two distinct configurations known as enantiomers. Understanding chirality is crucial for determining the configuration of molecules in organic chemistry.

Fischer Projections

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

Stereocenters

Stereocenters, or chiral centers, are atoms in a molecule that have four different substituents attached, leading to different spatial arrangements. The configuration of these centers can be designated as R (rectus) or S (sinister) based on the Cahn-Ingold-Prelog priority rules. Identifying stereocenters is essential for determining the overall stereochemistry of a compound.