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 Configuration

Organic Chemistry

5. Chirality

R and S Configuration

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6:41 minutes

Problem 6i

Textbook Question

Star (*) each asymmetric carbon atom in the following examples, and determine whether it has the (R) or (S) configuration.
(i)

Verified step by step guidance

Step 1: Identify all asymmetric carbon atoms in the molecule. An asymmetric carbon atom is a carbon atom bonded to four different groups. In the given structure, the central carbon atom is bonded to CHO, CH(CH3)2, CH=CH2, and (CH3O)2CH, making it asymmetric.

Step 2: Assign priorities to the four substituents attached to the asymmetric carbon based on the Cahn-Ingold-Prelog priority rules. The priority is determined by the atomic number of the atoms directly attached to the carbon. If two substituents have the same atomic number, consider the atoms further along the chain.

Step 3: Orient the molecule so that the lowest priority group (usually hydrogen or the group with the lowest atomic number) is pointing away from you. In this case, determine the spatial arrangement of the groups around the asymmetric carbon.

Step 4: Trace a path from the highest priority group to the second highest, then to the third highest. If the path is clockwise, the configuration is (R). If the path is counterclockwise, the configuration is (S).

Step 5: Confirm the configuration by double-checking the priority assignments and the spatial arrangement of the groups. Label the asymmetric carbon with its configuration (R) or (S).

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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 contains at least one asymmetric carbon atom, which is bonded to four different substituents. This property is crucial in organic chemistry as it affects the molecule's interactions and biological activity.

R and S Configuration

The R and S configuration system is used to describe the spatial arrangement of substituents around a chiral center. To assign R (rectus) or S (sinister) configuration, the substituents are ranked based on atomic number, and the orientation is determined by viewing the molecule with the lowest priority substituent pointing away. This system is essential for understanding the stereochemistry of chiral compounds.

Cahn-Ingold-Prelog Priority Rules

The Cahn-Ingold-Prelog priority rules are a set of guidelines used to assign priority to substituents attached to a chiral center. According to these rules, higher atomic number atoms take precedence over lower ones, and if two atoms are the same, the next atoms in the chain are compared. This systematic approach is vital for accurately determining the R or S configuration of chiral centers.

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Star (*) each asymmetric carbon atom in the following examples, and determine whether it has the (R) or (S) configuration.

(a)

(b)

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