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 22a

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)

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, connectivity, and bonding.

Step 2: Analyze the substituents in the given pair. The first substituent is a hydroxyl group (-OH) attached to a single-bonded carbon (R-CH(OH)). The second substituent is a hydroxyl group (-OH) attached to a double-bonded carbon (R-C(OH)=C).

Step 3: Compare the atomic numbers of the atoms directly attached to the asymmetric center. Both substituents have oxygen atoms directly attached, so the comparison moves to the next level of connectivity.

Step 4: Evaluate the connectivity of the carbon atoms bonded to the oxygen. In the first substituent, the carbon is single-bonded to other atoms, while in the second substituent, the carbon is double-bonded. Double bonds increase priority because they are treated as if the atom is bonded to two identical atoms.

Step 5: Conclude that the substituent with the double-bonded carbon (R-C(OH)=C) has higher priority according to the CIP rules, as the double bond increases the effective atomic connectivity.

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Key Concepts

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

CIP Rules (Cahn-Ingold-Prelog)

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 are based on the atomic number of the atoms directly attached to the chiral center; higher atomic numbers receive higher priority. If the first atoms are the same, the comparison continues to the next atoms in the substituent chain until a difference is found.

Chirality and Asymmetric Centers

Chirality refers to the property of a molecule that makes it non-superimposable on its mirror image, often due to the presence of an asymmetric center, typically a carbon atom bonded to four different substituents. The configuration of these substituents around the asymmetric center is crucial for determining the molecule's optical activity and its interactions in biological systems.

Substituent Priority

Substituent priority is determined by the CIP rules and is essential for distinguishing between different stereoisomers. In a pair of substituents, the one with the higher priority will influence the overall stereochemistry of the molecule. Understanding how to evaluate and compare substituents based on their atomic composition and connectivity is key to correctly applying the CIP rules in stereochemical analysis.

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