Chapter 5, Problem 5.47P

Label each stereogenic center as $R$ or $S$.

a. c. e. g.

b. d. f. h.

Interpretation Introduction

(a)

Interpretation: The stereogenic center in the given compound is to be labeled as $R$ or $S$.

Concept introduction: A carbon atom that has four nonequivalent atoms or groups attached to it is known as chiral carbon atom. Chiral carbon centers are also called as asymmetric or stereogenic centers.

The naming of chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chirality center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other.

Answer to Problem 5.47P

The stereogenic center has $S$ configuration.

Explanation of Solution

The $R$ or $S$ configuration can be assigned by following CIP rules as follows.

(1) Assign numbering to the groups which are bonded to the chiral carbon based on the molecular weight and electronegativity.

(2) If the sequence of the numbering follows clockwise direction, the chiral atom is assigned $R$ configuration.

(3) If the sequence of the numbering follows anticlockwise direction, the chiral atom is assigned $S$ configuration.

(4) If the rotation is clock-wise and the least priority group is above the plane, then the configuration is inverted to the obtained configuration from the above CIP rule which means $R$ configuration becomes $S$ and vice versa.

In the given compound, the increasing order of priority assigned to the groups attached to chiral center is,

$\text{H}<{\text{CH}}_{\text{3}}<{\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}<\text{I}$

Therefore, the groups in the given compound are numbered as shown below.

Figure 1

The rotation in the above compound is in anticlockwise direction. Hence, the stereogenic center has $S$ configuration.

Interpretation Introduction

(b)

Interpretation: The stereogenic center in the given compound is to be labeled as $R$ or $S$.

Concept introduction: A carbon atom that has four nonequivalent atoms or groups attached to it is known as chiral carbon atom. Chiral carbon centers are also called as asymmetric or stereogenic centers.

The naming of chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chirality center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other.

Answer to Problem 5.47P

The stereogenic center has $S$ configuration.

Explanation of Solution

In the given compound, the increasing order of priority assigned to the groups attached to chiral center is,

$\text{H}<{\text{CH}}_{\text{3}}<{\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}<{\text{NH}}_{\text{2}}$

Therefore, the groups in the given compound are numbered as shown below.

Figure 2

The rotation in the above compound is in clockwise direction and the least priority group is above the plane, then the configuration is inverted. Hence, the stereogenic center has $S$ configuration.

Interpretation Introduction

(c)

Interpretation: The stereogenic center in the given compound is to be labeled as $R$ or $S$.

Concept introduction: A carbon atom that has four nonequivalent atoms or groups attached to it is known as chiral carbon atom. Chiral carbon centers are also called as asymmetric or stereogenic centers.

The naming of chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chirality center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other.

Answer to Problem 5.47P

The stereogenic center has $R$ configuration.

Explanation of Solution

In the given compound, the increasing order of priority assigned to the groups attached to chiral center is,

$\text{H}<{\text{CH}}_{\text{2}}\text{I}<\text{Cl}<\text{Br}$

Therefore, the groups in the given compound are numbered as shown below.

Figure 3

The rotation in the above compound is in clockwise direction. Hence, the stereogenic center has $R$ configuration.

Interpretation Introduction

(d)

Interpretation: The stereogenic center in the given compound is to be labeled as $R$ or $S$.

Concept introduction: A carbon atom that has four nonequivalent atoms or groups attached to it is known as chiral carbon atom. Chiral carbon centers are also called as asymmetric or stereogenic centers.

The naming of chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chirality center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other.

Answer to Problem 5.47P

Both the stereogenic centers has $R$ configuration.

Explanation of Solution

In the given compound, two chiral centers are present.

Therefore, the groups in the given compound are numbered as shown below.

Figure 4

The rotation of first chiral center in the above compound is in clockwise direction and second chiral center shows anticlockwise rotation. In second chiral center, the least priority group is above the plane, and then the configuration is inverted. Hence, both the stereogenic centers has $R$ configuration.

Interpretation Introduction

(e)

Interpretation: The stereogenic center in the given compound is to be labeled as $R$ or $S$.

Concept introduction: A carbon atom that has four nonequivalent atoms or groups attached to it is known as chiral carbon atom. Chiral carbon centers are also called as asymmetric or stereogenic centers.

The naming of chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chirality center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other.

Answer to Problem 5.47P

The stereogenic center has $S$ configuration.

Explanation of Solution

The groups in the given compound are numbered as shown below.

Figure 5

The rotation in the above compound is in anticlockwise direction and the least priority group is below the plane. Hence, the stereogenic center has $S$ configuration.

Interpretation Introduction

(f)

Interpretation: The stereogenic center in the given compound is to be labeled as $R$ or $S$.

Concept introduction: A carbon atom that has four nonequivalent atoms or groups attached to it is known as chiral carbon atom. Chiral carbon centers are also called as asymmetric or stereogenic centers.

The naming of chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chirality center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other.

Answer to Problem 5.47P

Both the stereogenic centers has $S$ configuration.

Explanation of Solution

In the given compound, two chiral centers are present.

Therefore, the groups in the given compound are numbered as shown below.

Figure 6

The rotation of first chiral center in the above compound is in clockwise direction and second chiral center shows anticlockwise rotation. In first chiral center, the highest priority group is below the plane, and then the configuration is inverted to $S$ configuration. Hence, both the stereogenic centers has $S$ configuration.

Interpretation Introduction

(g)

Interpretation: The stereogenic center in the given compound is to be labeled as $R$ or $S$.

Concept introduction: A carbon atom that has four nonequivalent atoms or groups attached to it is known as chiral carbon atom. Chiral carbon centers are also called as asymmetric or stereogenic centers.

The naming of chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chirality center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other.

Answer to Problem 5.47P

Both the stereogenic centers has $S$ configuration.

Explanation of Solution

In the given compound, two chiral centers are present.

Therefore, the groups in the given compound are numbered as shown below.

Figure 7

The rotation of first chiral center in the above compound is in clockwise direction and second chiral center shows anticlockwise rotation. In first chiral center, the highest priority group is below the plane, and then the configuration is inverted to $S$ configuration. Hence, both the stereogenic centers has $S$ configuration.

Interpretation Introduction

(h)

Interpretation: The stereogenic center in the given compound is to be labeled as $R$ or $S$.

Concept introduction: A carbon atom that has four nonequivalent atoms or groups attached to it is known as chiral carbon atom. Chiral carbon centers are also called as asymmetric or stereogenic centers.

The naming of chiral center and geometric isomers are based on Cahn-Ingold-Prelog priority rules. If the priority assigned to each group attached to the chirality center in a molecule is in a clockwise direction, then it is the R-stereoisomer, and if this is counter-clockwise, then it is the S-stereoisomer. R and S-stereoisomer are mirror images of each other.

Answer to Problem 5.47P

The configurations of three stereogenic centers are $R$, $S$ and $S$.

Explanation of Solution

In the given compound, three chiral centers are present.

Therefore, the groups in the given compound are numbered as shown below.

Figure 8

The rotation of first chiral center in the above compound is in clockwise direction. Thus, it has $R$ configuration. Second chiral center shows anticlockwise rotation and possess $S$ configuration. In third chiral center, the highest priority group is below the plane, and then the configuration is inverted from $R$ to $S$ configuration. Hence, the configurations of three stereogenic centers are $R$, $S$ and $S$.

Conclusion

(a) The stereogenic center has $S$ configuration.

(b) The stereogenic center has $S$ configuration.

(c) The stereogenic center has $R$ configuration.

(d) Both the stereogenic centers has $R$ configuration.

(e) Both the stereogenic centers has $S$ configuration.

(f) Both the stereogenic centers has $S$ configuration.

(g) Both the stereogenic centers has $S$ configuration.

(h) The configurations of three stereogenic centers are $R$, $S$ and $S$.