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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Problem 20a

Textbook Question

Order the following sets of substituents via their priority using the CIP rules. (R = position of attachment to the asymmetric center.)
(a)

Verified step by step guidance

Step 1: Understand the CIP (Cahn-Ingold-Prelog) priority rules. These rules are used to assign priorities to substituents attached to a chiral center based on atomic number, isotopic mass, and connectivity. The substituent with the highest atomic number directly attached to the chiral center gets the highest priority.

Step 2: Analyze the substituents provided: R-N (amine group), R-OH (hydroxyl group), R-NH2 (amino group), and R-Br (bromo group). Focus on the atom directly attached to the chiral center (R).

Step 3: Compare the atomic numbers of the atoms directly attached to the chiral center: Nitrogen (N, atomic number 7), Oxygen (O, atomic number 8), Bromine (Br, atomic number 35). Bromine has the highest atomic number, followed by Oxygen, then Nitrogen.

Step 4: For substituents with the same atom directly attached (e.g., R-N and R-NH2), consider the connectivity and the number of bonds to other atoms. R-N has a nitrogen atom bonded to two other groups, while R-NH2 has a nitrogen atom bonded to one hydrogen and one group. R-N will have higher priority than R-NH2.

Step 5: Order the substituents based on priority: R-Br > R-OH > R-N > R-NH2. This ranking follows the CIP rules considering atomic number and connectivity.

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Key Concepts

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

CIP Rules

The Cahn-Ingold-Prelog (CIP) rules are a set of guidelines used to assign priority to substituents attached to a chiral center in organic molecules. These rules prioritize substituents based on atomic number, with higher atomic numbers receiving higher priority. If two substituents have the same atom, the priority is determined by the next atoms in the substituent chain, continuing until a difference is found.

Chirality

Chirality refers to the geometric property of a molecule that makes it non-superimposable on its mirror image, much like left and right hands. Molecules that possess chirality typically have a carbon atom bonded to four different substituents, creating an asymmetric center. Understanding chirality is crucial for determining the stereochemistry of compounds and their interactions in biological systems.

Substituent Priority

Substituent priority is the ranking of different groups attached to a chiral center based on the CIP rules. This ranking is essential for determining the configuration of the chiral center, which can be designated as either R (rectus) or S (sinister) based on the arrangement of the substituents. Correctly identifying the priority of substituents is vital for accurately describing the stereochemistry of organic compounds.

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Related Practice

Textbook Question

Draw the structure that corresponds to the compound names shown.

(b) (5R,6E)-5-bromooct-6-en-1-yne

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Given the following IUPAC names, draw the corresponding structures.

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Draw the structures that correspond to the following names.

(b) (3Z,8S)-8-ethyl-3-methylundec-3-en-6-yne

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Textbook Question

By comparing them to the models you created in Section 6.3.2, label the following chiral centers as R or S.

(j)

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Textbook Question

Of the following pairs, identify the higher priority substituent according to the CIP rules. (R = position of attachment to the asymmetric center.)

(a)

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Textbook Question

Prioritize the substituents at each chiral center and then, by comparing them to the models you created in Section 6.3.2, label the absolute configuration as R or S.

(a)

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Textbook Question

Prioritize the substituents at each chiral center and then, by each of the two methods discussed in Section 6.3.2.4, determine the absolute configuration. [Do not use your models, except to check your answers.]

(c)

(d)