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Ch.5 - Stereochemistry
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
All textbooksWade 9th EditionCh.5 - StereochemistryProblem 26f
Chapter 5, Problem 26f

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) Fischer projection showing asymmetric carbon atoms, labeled (R) and (S), with mirror planes and chiral/achiral designations.

Verified step by step guidance
1
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.
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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.
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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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Related Practice
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.

(e)

1060
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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.

(g)

(h)

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Textbook Question

For each of the compounds described by the following names,

1. draw a three-dimensional representation.

2. star (*) each chiral center.

3. draw any planes of symmetry.

4. draw any enantiomer.

5. draw any diastereomers.

6. label each structure you have drawn as chiral or achiral.

a. (S)-2-chlorobutane

b. (R)-1,1,2-trimethylcyclohexane

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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.

(a)

(b)

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1
rank
Textbook Question

For each of the compounds described by the following names,

1. draw a three-dimensional representation.

2. star (*) each chiral center.

3. draw any planes of symmetry.

4. draw any enantiomer.

5. draw any diastereomers.

6. label each structure you have drawn as chiral or achiral.

c. (2R,3S)-2,3-dibromohexane

d. (1R,2R)-1,2-dibromocyclohexane

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Textbook Question

The following four structures are naturally occurring optically active compounds. Star (*) the asymmetric carbon atoms in these structures.

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