Chapter 16, Problem 16.9P

Draw the structure consistent with each description.

a. $\left(2E,4E\right)-\text{octa}-2,4-\text{diene}$ in the $\text{s}-\text{trans}$ conformation

b. $\left(3E,5Z\right)-\text{nona}-3,5-\text{diene}$ in the $\text{s}-\text{trans}$ conformation

c. $\left(3Z,5Z\right)-4,5-\text{dimethyldeca}-3,5-\text{diene}$. Draw both the s-cis and s-trans conformations.

Interpretation Introduction

(a)

Interpretation: The structure corresponding to $\left(2E,4E\right)-\text{octa}-2,4-\text{diene}$ in the $\text{s}-\text{trans}$ conformation is to be drawn.

Concept introduction: The systematic naming of organic compound is given by IUPAC. The naming of organic compound is done such that the structure of organic compound is correctly interpreted from the name.

Rules for writing structural formula from IUPAC are:

1. First identify the word root for the given compound.

2. The suffix used in the compound like –ene.

3. Identify the position, location, and number of the substituent bonded to the carbon chain.

The prefix $E$ and $Z$ depends upon the location of the higher priority groups. When two higher priority groups are present on the opposite side then it is an $E$ isomer, whereas when two higher priority groups are present on the same side then it is $Z$ isomer.

Answer to Problem 16.9P

The structure corresponding to $\left(2E,4E\right)-\text{octa}-2,4-\text{diene}$ in the $\text{s}-\text{trans}$ conformation is shown as:

Explanation of Solution

The given name is $\left(2E,4E\right)-\text{octa}-2,4-\text{diene}$. The word root used in this is oct. It means structure contains eight carbon atoms. The hydrocarbons that are attached to the longest chain are called substituents and they are written as prefix in alphabetical order. The prefix used is $E$. Thus, it means that the two double bonds are present on the opposite side.

Thus, the correct structure of $\left(2E,4E\right)-\text{octa}-2,4-\text{diene}$ is shown below.

Figure 1

Conclusion

The structure corresponding to $\left(2E,4E\right)-\text{octa}-2,4-\text{diene}$ in the $\text{s}-\text{trans}$ conformation is shown in Figure 1.

Interpretation Introduction

(b)

Interpretation: The structure corresponding to $\left(3E,5Z\right)-\text{nona}-3,5-\text{diene}$ in the $\text{s}-\text{cis}$ conformation is to be drawn.

Concept introduction: The systematic naming of organic compound is given by IUPAC. The naming of organic compound is done such that the structure of organic compound is correctly interpreted from the name.

Rules for writing structural formula from IUPAC are:

1. First identify the word root for the given compound.

2. The suffix used in the compound like –ene.

3. Identify the position, location, and number of the substituent bonded to the carbon chain.

The prefix $E$ and $Z$ depends upon the location of the higher priority groups. When two higher priority groups are present on the opposite side then it is an $E$ or trans isomer, whereas when two higher priority groups are present on the same side then it is $Z$ or cis isomer.

Answer to Problem 16.9P

The structure corresponding to $\left(3E,5Z\right)-\text{nona}-3,5-\text{diene}$ in the $\text{s}-\text{trans}$ conformation is shown as:

Explanation of Solution

The given name is $\left(3E,5Z\right)-\text{nona}-3,5-\text{diene}$. The word root used in this is non. It means structure contains nine carbon atoms. The hydrocarbons that are attached to the longest chain are called substituents and they are written as prefix in alphabetical order. The prefix used are $E$ and $Z$. Thus, it means that the stereochemistry at one double bond is trans and at other is cis.

Thus, the correct structure of $\left(3E,5Z\right)-\text{nona}-3,5-\text{diene}$ is shown below.

Figure 2

Conclusion

The structure corresponding to $\left(3E,5Z\right)-\text{nona}-3,5-\text{diene}$ in the $\text{s}-\text{trans}$ conformation is shown in Figure 2.

Interpretation Introduction

(c)

Interpretation: The structure corresponding to $\text{s}-\text{trans}$ and $\text{s}-\text{cis}$ conformation of $\left(3Z,5Z\right)-4,5-\text{dimethyldeca}-3,5-\text{diene}$ is to be drawn.

Concept introduction: The systematic naming of organic compound is given by IUPAC. The naming of organic compound is done such that the structure of organic compound is correctly interpreted from the name.

Rules for writing structural formula from IUPAC are:

1. First identify the word root for the given compound.

2. The suffix used in the compound like –ene.

3. Identify the position, location, and number of the substituent bonded to the carbon chain.

The prefix $E$ and $Z$ depends upon the location of the higher priority groups. When two higher priority groups are present on the opposite side then it is an $E$ isomer, whereas when two higher priority groups are present on the same side then it is $Z$ isomer.

Answer to Problem 16.9P

The structures corresponding to $\text{s}-\text{trans}$ and $\text{s}-\text{cis}$ conformation of $\left(3Z,5Z\right)-4,5-\text{dimethyldeca}-3,5-\text{diene}$ are:

Explanation of Solution

The given name is $\left(3Z,5Z\right)-4,5-\text{dimethyldeca}-3,5-\text{diene}$. The word root used in this is dec. It means structure contains ten carbon atoms. The hydrocarbons that are attached to the longest chain are called substituents and they are written as prefix in alphabetical order. The prefix used is $Z$. Thus, it means that the two double bonds are present on the same side.

Thus, the correct structure to $\text{s}-\text{trans}$ and $\text{s}-\text{cis}$ conformation of $\left(3Z,5Z\right)-4,5-\text{dimethyldeca}-3,5-\text{diene}$ is shown below.

Figure 3

Conclusion

The structure corresponding to $\text{s}-\text{trans}$ and $\text{s}-\text{cis}$ conformation of $\left(3Z,5Z\right)-4,5-\text{dimethyldeca}-3,5-\text{diene}$ is shown in Figure 3.