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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2:17 minutes

Problem 26f

Textbook Question

For each structure,
1. star (*) any asymmetric carbon atoms.
2. label each asymmetric carbon as (R) or (S).
3. draw any internal mirror planes of symmetry.
4. label the structure as chiral or achiral.
5. label any meso structures.
(f)

Verified step by step guidance

Step 1: Identify all carbon atoms in the structure and determine if they are asymmetric. An asymmetric carbon is bonded to four different groups. In this structure, the two central carbon atoms are candidates for asymmetry. Analyze the groups attached to each carbon atom to confirm asymmetry.

Step 2: Assign the configuration (R or S) to each asymmetric carbon atom using the Cahn-Ingold-Prelog priority rules. Assign priorities to the substituents based on atomic number, and determine the stereochemistry by observing the arrangement of groups in 3D space. Use the right-hand rule to assign (R) or (S).

Step 3: Check for internal mirror planes of symmetry in the molecule. A mirror plane divides the molecule into two identical halves. Analyze the structure to see if such a plane exists.

Step 4: Determine if the molecule is chiral or achiral. A molecule is chiral if it lacks a plane of symmetry and cannot be superimposed on its mirror image. If a plane of symmetry exists, the molecule is achiral.

Step 5: Identify if the molecule is a meso compound. A meso compound is achiral despite having asymmetric carbons due to the presence of an internal plane of symmetry. Confirm if the molecule fits this definition.

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Key Concepts

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

Asymmetric Carbon Atoms

Asymmetric carbon atoms, also known as chiral centers, are carbon atoms that are bonded to four different substituents. This unique arrangement allows for the existence of two non-superimposable mirror images, known as enantiomers. Identifying these atoms is crucial for determining the chirality of a molecule, which influences its chemical behavior and interactions.

Cahn-Ingold-Prelog Priority Rules

The Cahn-Ingold-Prelog (CIP) priority rules are a systematic method for assigning the (R) or (S) configuration to chiral centers. According to these rules, substituents attached to the asymmetric carbon are ranked based on atomic number, with higher atomic numbers receiving higher priority. The configuration is determined by the orientation of the substituents when the lowest priority group is oriented away from the viewer.

Chirality and Meso Compounds

Chirality refers to the property of a molecule that is not superimposable on its mirror image, indicating that it has a distinct 'handedness.' Meso compounds, however, are a special case of chirality where a molecule contains multiple chiral centers but is overall achiral due to an internal plane of symmetry. Recognizing meso structures is essential for accurately labeling the chirality of complex molecules.

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