Chapter 28, Problem 28.39P

Interpretation Introduction

(a)

Interpretation: The given compound is to be classified as identical to $A$ or its enantiomer.

Concept introduction: The stereochemistry of the compound is determined by prioritizing the groups attached to its stereogenic center. The groups are prioritized on the basis of atomic number of their atoms. The group that contain atom with higher atomic number is given higher priority. Complete the circle in decreasing order of priority from $1\to 2\to 3$. The configuration of the compound is R and S when circle rotates in clockwise and anticlockwise direction.

Answer to Problem 28.39P

The given compound is classified as identical to $A$ because the configuration of $A$ is same to the configuration of the given compound i.e. $R$.

Explanation of Solution

The structure of compound $A$ is,

Figure 1

In the compound $A$, ${\text{CHO, OH, CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ and $\text{H}$ substituents are attached to carbon atom. The atomic number of $\text{C, O}$ and $\text{H}$ is $\text{6, 8}$ and $1$ respectively. Thus, first priority is given to $\text{OH}$ substituent. There are two substituents i.e. ${\text{CHO, CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ connected to the stereogenic centre through the carbon atom. Now, the priority is given on the basis of atomic number of second atom which is attached to the carbon atom. The carbon of $\text{CHO}$ is connected to the oxygen atom and the atomic number of oxygen is $8$ while the another carbon atom of ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ is connected to the carbon atom and the atomic number of carbon is $6$. Thus, the second priority is given to $\text{CHO}$ substituent then third priority to ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ substituent. Complete the circle in decreasing order of priority from $1\to 2\to 3$ is shown below.

Figure 2

The circle rotates in the anticlockwise direction and its configuration will be $S$ but the lowest priority group should be away from the viewer i.e. lies on vertical lineas shown below.

Figure 3

Thus, the configuration will reverse. Therefore, the compound $A$ is labeled as $R$.

The given compound is,

Figure 4

In the given compound, ${\text{CHO, OH, CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ and $\text{H}$ substituents are attached to carbon atom. The atomic number of $\text{C, O}$ and $\text{H}$ is $\text{6, 8}$ and $1$ respectively. Thus, first priority is given to $\text{OH}$ substituent. There are two substituents i.e. ${\text{CHO, CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ are connected to the stereogenic centre through carbon atom. Now, the priority is given on the basis of atomic number of second atom which is attached to the carbon atom. The carbon of $\text{CHO}$ is to connected the oxygen atom and the atomic number of oxygen is $8$ while the another carbon atom of ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ is connected to the carbon atom and the atomic number of carbon is $6$. Thus, the second priority is given to $\text{CHO}$ substituent then third priority to ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ substituent. Complete the circle in decreasing order of priority from $1\to 2\to 3$ is shown below.

Figure 5

The circle rotates in the clockwise direction. Thus, the given compound is labeled as $R$.

Hence, the given compound is classified as identical to $A$ because the configuration of $A$ is same to the configuration of the given compound i.e. $R$.

Conclusion

The given compound is classified as identical to $A$ because the configuration of $A$ is same to the configuration of the given compound i.e. $R$.

Interpretation Introduction

(b)

Interpretation: The given compound is to be classified as identical to $A$ or its enantiomer.

Concept introduction: The stereochemistry of the compound is determined by prioritizing the groups attached to its stereogenic center. The groups are prioritized on the basis of atomic number of their atoms. The group that contain atom with higher atomic number is given higher priority. Complete the circle in decreasing order of priority from $1\to 2\to 3$. The configuration of the compound is R and S when circle rotates in clockwise and anticlockwise direction.

Answer to Problem 28.39P

The given compound is classified as identical to $A$ because the configuration of $A$ is same to the configuration of the given compound i.e. $R$.

Explanation of Solution

The compound $A$ is labeled as $R$.

The given compound is,

Figure 6

In the given compound, ${\text{CHO, OH, CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ and $\text{H}$ substituents are attached to carbon atom. The atomic number of $\text{C, O}$ and $\text{H}$ is $\text{6, 8}$ and $1$ respectively. Thus, first priority is given to $\text{OH}$ substituent. There are two substituents i.e. ${\text{CHO, CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ are connected to the stereogenic centre through carbon atom. Now, the priority is given on the basis of atomic number of second atom which is attached to the carbon atom. The carbon of $\text{CHO}$ is connected to the oxygen atom and the atomic number of oxygen is $8$ while the another carbon atom of ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ is connected to the carbon atom and the atomic number of carbon is $6$. Thus, the second priority is given to $\text{CHO}$ substituent then third priority to ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ substituent. Complete the circle in decreasing order of priority from $1\to 2\to 3$ is shown below.

Figure 7

The circle rotates in the anticlockwise direction hence its configuration will be $S$ but the lowest priority group should be away from the viewer as shown below.

Figure 8

Thus, the configuration will reverse. Therefore, the compound is labeled as $R$.

Hence, the given compound is classified as identical to $A$ because the configuration of $A$ is same to the configuration of the given compound i.e. $R$.

Conclusion

The given compound is classified as identical to $A$ because the configuration of $A$ is same to the configuration of the given compound i.e. $R$.

Interpretation Introduction

(c)

Interpretation: The given compound is to be classified as identical to $A$ or its enantiomer.

Concept introduction: The stereochemistry of the compound is determined by prioritizing the groups attached to its stereogenic center. The groups are prioritized on the basis of atomic number of their atoms. The group that contain atom with higher atomic number is given higher priority. Complete the circle in decreasing order of priority from $1\to 2\to 3$. The configuration of the compound is R and S when circle rotates in clockwise and anticlockwise direction.

Answer to Problem 28.39P

The given compound is classified as enantiomer to $A$ because the configuration of $A$ is different from the configuration of the given compound.

Explanation of Solution

The compound $A$ is labeled as $R$.

The given compound is,

Figure 9

In the given compound, ${\text{CHO, OH, CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ and $\text{H}$ substituents are attached to carbon atom. The atomic number of $\text{C, O}$ and $\text{H}$ is $\text{6, 8}$ and $1$ respectively. Thus, first priority is given to $\text{OH}$ substituent. There are two substituents i.e. ${\text{CHO, CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ are connected to the stereogenic centre through carbon atom. Now, the priority is given on the basis of atomic number of second atom which is attached to the carbon atom. The carbon of $\text{CHO}$ is connected to the oxygen atom and the atomic number of oxygen is $8$ while the another carbon atom of ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ is connected to the carbon atom and the atomic number of carbon is $6$. Thus, the second priority is given to $\text{CHO}$ substituent then third priority to ${\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$ substituent. Complete the circle in decreasing order of priority from $1\to 2\to 3$ is shown below.

Figure 10

The circle rotates in the clockwise direction hence its configuration will be $R$ but the lowest priority group should be away from the viewer as shown below.

Figure 11

Thus, the configuration will reverse. Therefore, the compound is labeled as $S$.

The given compound and $A$ are enantiomer as shown below.

Figure 12

Hence, the given compound is classified as enantiomer to $A$ because the configuration of $A$ is different from the configuration of the given compound.

Conclusion

The given compound is classified as enantiomer to $A$ because the configuration of $A$ is different from the configuration of the given compound.