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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5:38 minutes

Problem 7c,d

Textbook Question

In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).
(c)
(d) 1-bromo-2-methylbutane

Verified step by step guidance

Step 1: Identify the chiral center in alanine (c). The chiral center is the carbon atom bonded to four different groups: NH₂, CH₃, H, and COOH.

Step 2: Assign priorities to the substituents around the chiral center in alanine based on the Cahn-Ingold-Prelog priority rules. The highest priority is given to the group with the atom of highest atomic number directly attached to the chiral center.

Step 3: Orient the molecule so that the lowest priority group (H) is pointing away from you. Then, determine the order of the remaining groups (1 → 2 → 3) and decide if the rotation is clockwise (R) or counterclockwise (S).

Step 4: For 1-bromo-2-methylbutane (d), identify the chiral center, which is the carbon atom bonded to four different groups: Br, CH₃, H, and CH₂CH₃.

Step 5: Repeat the process of assigning priorities, orienting the molecule, and determining the configuration (R or S) for 1-bromo-2-methylbutane using the Cahn-Ingold-Prelog rules.

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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. Molecules that possess chirality typically have one or more asymmetric carbon atoms, which are carbon atoms bonded to four different substituents. This property is crucial in organic chemistry as it affects the behavior of molecules in biological systems, influencing how they interact with enzymes and receptors.

R and S Nomenclature

The R and S nomenclature system is used to assign configurations to chiral centers in molecules. The Cahn-Ingold-Prelog priority rules are applied to determine the order of substituents attached to the chiral carbon. If the priority of the substituents decreases in a clockwise direction, the configuration is designated as (R); if it decreases counterclockwise, it is designated as (S). This system is essential for accurately describing the stereochemistry of chiral compounds.

Asymmetric Carbon Atom

An asymmetric carbon atom, also known as a chiral center, is a carbon atom that is bonded to four different groups or atoms. The presence of an asymmetric carbon is what gives rise to enantiomers, which are pairs of molecules that are mirror images of each other. Identifying and designating these carbon atoms is fundamental in understanding the stereochemistry of organic compounds, particularly in the context of biological activity and drug design.

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Related Practice

Textbook Question

Draw structures for the following:

a. (S)-1-bromo-1-chlorobutane

b. (2R,3R)-2,3-dichloropentane

c. an achiral stereoisomer of 1,2-dimethylcyclohexane

Textbook Question

In Problem 5-3 , you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).e. Chlorocyclohexane f. Cis-1,2-dichlorocyclobutane

Textbook Question

3,4-Dimethylpent-1-ene has the formula CH₂=CH—CH(CH₃)—CH(CH₃)₂. When pure (R)-3,4-dimethylpent-1-ene is treated with hydrogen over a platinum catalyst, the product is (S)-2,3-dimethylpentane.

a. Draw the equation for this reaction. Show the stereochemistry of the reactant and the product.

b. Has the chiral center retained its configuration during this hydrogenation, or has it been inverted?

Textbook Question

In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).

(e) chlorocyclohexane

(f) cis-1,2-dichlorocyclobutane

Textbook Question

In Problem 5-3, you drew the enantiomers for a number of chiral compounds. Now go back and designate each asymmetric carbon atom as either (R) or (S).

(a)

(b)

Textbook Question

c. The reactant is named (R), but the product is named (S). Does this name change imply a change in the spatial arrangement of the groups around the chiral center? So why does the name switch from (R) to (S)?

Textbook Question

Naproxen is a commercially available anti-inflammatory sold under the name Aleve.

(a) Assign the absolute configuration as R or S.

Textbook Question

Given the following IUPAC names, draw the corresponding structures.

(a) (R)-3-isopropyl-6-methylnon-1-ene

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