Chapter 4, Problem 4.46AP

Interpretation Introduction

(a)

Interpretation:

The correct IUPAC name of $3-\text{butene}$ is to be stated.

Concept introduction:

Alkenes are the unsaturated class of organic compounds which have a double bond in their structure. The general formula of alkene is written as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$. The systematic naming of organic compound is given by IUPAC nomenclature. The naming of organic compound is done such that the structure of the organic compound is correctly interpreted from the name.

Rules for writing IUPAC name from the structural formula are given below.

• First, identify the longest carbon chain.

• The next step is to identify the groups attached to the longest chain.

• Identify the position, location, and a number of the substituents bonded to the carbon chain.

• Use prefix di, tri, tetra if the same type of substituents are present.

• Name the substituents in alphabetical order.

Answer to Problem 4.46AP

The correct IUPAC name of $3-\text{butene}$ is $1-\text{butene}$.

Explanation of Solution

When a compound is named the first thing is to identify the longest parent chain. If the parent chain is substituted, then it is numbered in such a manner so that the substituent gets the lowest locant number. In the given case, the structure is written as shown below.

Figure 1

The method of numbering the parent chain is wrong because it is substituted by a double bond. It has to be numbered in such a way so that double bond gets the lowest locant number. The lowest locant number is $1$ not $3$. Therefore, the correct method to number the parent chain is written as shown below.

Figure 2

The structure is named as $1-\text{butene}$ not $3-\text{butene}$.

Conclusion

The correct IUPAC name of $3-\text{butene}$ is $1-\text{butene}$.

Interpretation Introduction

(b)

Interpretation:

The correct IUPAC name of $trans-1-tert-\text{butylpropene}$ is to be stated.

Concept introduction:

Alkenes are the unsaturated class of organic compounds which have a double bond in their structure. The general formula of alkene is written as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$. The systematic naming of organic compound is given by IUPAC nomenclature. The naming of organic compound is done such that the structure of the organic compound is correctly interpreted from the name.

Rules for writing IUPAC name from the structural formula are given below.

• First, identify the longest carbon chain.

• The next step is to identify the groups attached to the longest chain.

• Identify the position, location, and a number of the substituents bonded to the carbon chain.

• Use prefix di, tri, tetra if the same type of substituents are present.

• Name the substituents in alphabetical order.

Answer to Problem 4.46AP

The correct IUPAC name of $trans-1-tert-\text{butylpropene}$ is written as shown below.

$trans-4,4-\text{dimethylpent-2-ene}$

Explanation of Solution

When a compound is named the first thing is to identify the longest parent chain. If the parent chain is substituted, then it is numbered in such a manner so that the substituent gets the lowest locant number. In the given case the structure is drawn as shown below.

Figure 3

The given compound contains a double bond and two methyl groups. The double bond gets priority over the methyl group. It means double bond is marked locant number $2$ and methyl is marked as $4$. Since two methyl groups are present so, di prefix is used when it is named. The IUPAC name of the given structure is $trans-4,4-\text{dimethylpent-2-ene}$.

Conclusion

The correct IUPAC name of $trans-1-tert-\text{butylpropene}$ is $trans-4,4-\text{dimethylpent-2-ene}$.

Interpretation Introduction

(c)

Interpretation:

The correct IUPAC name of $\left(Z\right)-2-\text{hexene}$ is to be stated.

Concept introduction:

Alkenes are the unsaturated class of organic compounds which have a double bond in their structure. The general formula of alkene is written as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$. The systematic naming of organic compound is given by IUPAC nomenclature. The naming of organic compound is done such that the structure of the organic compound is correctly interpreted from the name.

Rules for writing IUPAC name from the structural formula are given below. First, identify the longest carbon chain.

• The next step is to identify the groups attached to the longest chain.

• Identify the position, location, and a number of the substituents bonded to the carbon chain.

• Use prefix di, tri, tetra if the same type of substituents are present.

• Name the substituents in alphabetical order.

Answer to Problem 4.46AP

The IUPAC name of $\left(Z\right)-2-\text{hexene}$ is correct.

Explanation of Solution

When a compound is named the first thing is to identify the longest parent chain. If the parent chain is substituted, then it is numbered in such a manner so that the substituent gets the lowest locant number. The structure is written as shown below.

Figure 4

The parent chain contain six carbon atoms so its parent name is hex. It contains a double bond at position $2$ which is the lowest locant number for this double bond. Since the double bond is present as $Z$ form because carbon atoms are present on the same side of the double bond. Therefore, the given name is correct which is $\left(Z\right)-2-\text{hexene}$.

Conclusion

The IUPAC name of $\left(Z\right)-2-\text{hexene}$ is found to be correct.

Interpretation Introduction

(d)

Interpretation:

The correct IUPAC name of $6-\text{methylcycloheptene}$ is to be stated.

Concept introduction:

Alkenes are the unsaturated class of organic compounds which have a double bond in their structure. The general formula of alkene is written as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$. The systematic naming of organic compound is given by IUPAC nomenclature. The naming of organic compound is done such that the structure of the organic compound is correctly interpreted from the name.

Rules for writing IUPAC name from the structural formula are given below.

• First, identify the longest carbon chain.

• The next step is to identify the groups attached to the longest chain.

• Identify the position, location, and a number of the substituents bonded to the carbon chain.

• Use prefix di, tri, tetra if the same type of substituents are present.

• Name the substituents in alphabetical order.

Answer to Problem 4.46AP

The correct IUPAC name of $6-\text{methylcycloheptene}$ is $4-\text{methylcycloheptene}$.

Explanation of Solution

When a compound is named the first thing is to identify the longest parent chain. If the parent chain is substituted, then it is numbered in such a manner so that the substituent gets the lowest locant number. In the given case, structure and numbering is written as shown below.

Figure 5

The method of numbering the parent chain is wrong because it is substituted by a double bond and a methyl group. It has to be numbered in such a way so that double bond and methyl group gets the lowest locant number. The lowest locant number for the double bond is $1$. Along with that the lowest locant number for the methyl is $4$ not $6$. Therefore, the correct method to number the parent chain is written as shown below.

Figure 6

The structure is named as $4-\text{methylcycloheptene}$.

Conclusion

The correct IUPAC name of $6-\text{methylcycloheptene}$ is $4-\text{methylcycloheptene}$.