Chapter 19, Problem 59PE

(a)

Interpretation Introduction

Interpretation:

The given structure has to be verified with its name by applying the IUPAC rules.  If it is incorrect, the correct name has determined.

Concept Introduction:

IUPAC rules for naming hydrocarbon:

• Identify the parent carbon chain in the given compound. The alkyl groups bonded to the parent chain are treated as substituents or branched chains. If two chains have the same carbon lengths, choose the chain with a greater number of substituents bonded to it. Name the parent compound based on the number of carbon atoms present in it.
• The parent carbon chain is numbered from the end of the chains whose alkyl groups must have the lowest possible locants.
• Identify and name the alkyl groups including their positions on the parent carbon chain.
• If the parent carbon chain contains two or more same kinds of alkyl groups, indicate this repetition by a numerical multiplier ($di\text{-}$, $tri\text{-}$ and so on) used before the alkyl-group name. The numbers for alkyl group positions are separated by a comma and the alkyl-group name and the position number is separated by a hyphen.
• If the parent carbon chain contains several different alkyl groups, arrange them in alphabetical order (do not consider numerical multipliers). Write all alkyl group names that include their locants in front of the parent compound’s name.

Explanation of Solution

The structure for the given condensed structural formula is redrawn by indicating the carbon numbers as shown below.

In the given compound, there are four carbons in the parent carbon chain. So, the parent compound’s name is $\text{butane}$. The parent carbon chain is numbered from the left end of the carbon chain as shown in the above structure. The methyl substituent, $-\text{C}{\text{H}}_3$ is identified on $\text{C-2}$ in the parent carbon chain. Hence, the complete IUPAC name for the given compound is $\text{2-methylbutane}$.

The given name is $\text{3-methylbutane}$ which is incorrect to the given condensed structure because the postion of the methyl group is wrong. Therefore, the correct name is $\text{2-methylbutane}$.

(b)

Interpretation Introduction

Interpretation:

The given structure has to be verified with its name by applying the IUPAC rules.  If it is incorrect, the correct name has determined.

Concept Introduction:

IUPAC rules for naming aromatic compounds:

The substituted benzenes are organic compounds that are derived from the benzene by substituting the benzene’s hydrogens with the functional groups or atoms except hydrogen.

For monosubstituted benzene:

The general molecular formula for the monosubstituted benzene is ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{G}$. Here, $\text{G}$ is the atom or group substituting one of the benzene’s hydrogens.

The substituent group or atom in the benzene ring is named in front of benzene.

For disubstituted benzene:

The substituents present on the benzene ring are named with their locants (numbers) or with the prefixes $ortho\text{-}$, $para\text{-}$ and $meta\text{-}$ to show the location correctly with respect to the first substituent having higher priority.

When one of the substituents in the disubstituted aromatic compounds has the special name for that monosubstituted compound, the parent compound name for the disubstituted is that special name.

Explanation of Solution

The structure for the given disubstituted aromatic compound is redrawn by indicating the carbon numbers as shown below.

The above structure has two bromine substituents on the benzene ring and has no special name. So, the benzene ring is numbered from the carbon atom having bromine as shown in the above structure. The bromine substituent, $-\text{Br}$ is named as bromo that is identified on both $\text{C-1}$ and $\text{C-3}$ in the benzene ring or at the meta- position. Hence, the full IUPAC name for the given aromatic compound is $\text{1,3-dibromobenzene}$ or $meta\text{-dibromobenzene}$.

The given name is $ortho\text{-dibromobenzene}$ which is incorrect to the given aromatic structure because the postion of the bromine groups is wrong. Therefore, the correct name is $meta\text{-dibromobenzene}$.

(c)

Interpretation Introduction

Interpretation:

The given structure has to be verified with its name by applying the IUPAC rules.  If it is incorrect, the correct name has determined.

Concept Introduction:

IUPAC rules for naming alkenes and alkynes:

• Identify the parent carbon chain in the given compound that must contain the carbon-carbon double or triple bonds. If two or more chains have the same carbon lengths, choose the chain with a greater number of substituents bonded to it.
• The alkene or alkyne name is derived from the corresponding alkane. Thus, the parent compound name is derived by replacing the $\text{-}ane$ ending of the alkane to $\text{-}ene$ for the alkene and $\text{-}yne$  for the alkyne. If two or more structural isomers are possible, use the position number for the alkene and alkyne groups.
• The parent carbon chain is always numbered from the begning of the chain only if the alkene or alkyne group has the lowest possible locant.
• Identify and name the alkyl groups including their positions on the parent carbon chain.
• If the parent carbon chain contains two or more same kinds of alkyl groups, indicate this repetition by a numerical multiplier ($di\text{-}$, $tri\text{-}$ and so on) used before the alkyl-group name. The numbers for alkyl group positions are separated by a comma and the alkyl-group name and the position number is separated by a hyphen.
• If the parent carbon chain contains several different alkyl groups, arrange them in alphabetical order (do not consider numerical multipliers). Write all alkyl group names that include their locants in front of the parent compound’s name.

Explanation of Solution

The structure for the given condensed structural formula is redrawn by indicating the carbon numbers as shown below.

There are four carbons in the parent carbon chain. The given compound is unsaturated hydrocarbon because the parent carbon chain contains the carbon-carbon triple bond between $\text{C-1}$ and $\text{C-2}$. So, the parent compound’s name is $\text{1-butyne}$. The parent carbon chain is numbered from the left end of the carbon chain as shown in the above structure. The methyl substituent, $-\text{C}{\text{H}}_3$ is identified on $\text{C-3}$ in the parent carbon chain. Hence, the complete IUPAC name for the given compound is $\text{2-methyl-1-butyne}$.

The given name is $\text{2-methyl-1-butyne}$ which is correct to the condensed structure. Therefore, the given name for the structure is correct.

(d)

Interpretation Introduction

Interpretation:

The given structure has to be verified with its name by applying the IUPAC rules.  If it is incorrect, the correct name has determined.

Concept Introduction:

IUPAC rules for naming alcohols:

• Identify the parent carbon chain in the given compound that must contain the hydroxyl functional group. If two or more chains have the same carbon lengths, choose the chain with a greater number of substituents bonded to it.
• The alcohol IUPAC name is derived from the respective alkane. Thus, the parent compound name is derived by replacing the $\text{-}e$ ending of the alkane to $\text{-}ol$. If two or more structural isomers are possible, use the position number for the hydroxyl group.
• The parent carbon chain is always numbered from the end of the chain only if the hydroxyl group has the lowest possible locant.
• Identify and name the alkyl groups including their positions on the parent carbon chain.
• If the parent carbon chain contains two or more same kinds of alkyl groups, indicate this repetition by a numerical multiplier ($di\text{-}$, $tri\text{-}$ and so on) used before the alkyl-group name. The numbers for alkyl group positions are separated by a comma and the alkyl-group name and the position number is separated by a hyphen.
• If the parent carbon chain contains several different alkyl groups, arrange them in alphabetical order (do not consider numerical multipliers). Write all alkyl group names that include their locants in front of the parent compound’s name.

Explanation of Solution

The structure for the given condensed structural formula is redrawn by indicating the carbon numbers as shown below.

In the given compound, there are five carbons in the parent carbon chain. So, the parent compound’s name is $\text{pentane}$. The parent carbon chain is numbered from the left end of the carbon chain as shown in the above structure. The hydroxyl functional group, $-\text{OH}$ is identified on $\text{C-3}$ in the parent carbon chain. Hence, the complete IUPAC name for the given compound is $\text{3-pentanol}$.

The given name is $\text{pentanol}$ which is incorrect to the given condensed structure because the position of the hydroxyl group is not shown. Therefore, the correct name is $\text{3-pentanol}$.

(e)

Interpretation Introduction

Interpretation:

The given structure has to be verified with its name by applying the IUPAC rules.  If it is incorrect, the correct name has determined.

Concept Introduction:

IUPAC rules for naming carboxylic acids:

• Identify the parent carbon chain in the given compound must contain the carboxyl functional group at the end. If two or more chains have the same carbon lengths, choose the chain with a greater number of substituents bonded to it.
• The carboxylic acid IUPAC name is derived from the respective alkane. Thus, the parent compound name is devised by replacing the $\text{-}e$ ending of the alkane to $\text{-}oicacid$.
• The parent carbon chain is always numbered from the carboxyl group end.
• Identify and name the alkyl groups including their positions on the parent carbon chain.
• If the parent carbon chain contains two or more same kinds of alkyl groups, indicate this repetition by a numerical multiplier ($di\text{-}$, $tri\text{-}$ and so on) used before the alkyl-group name. The numbers for alkyl group positions are separated by a comma and the alkyl-group name and the position number is separated by a hyphen.
• If the parent carbon chain contains several different alkyl groups, arrange them in alphabetical order (do not consider numerical multipliers). Write all alkyl group names that include their locants in front of the parent compound’s name.

Explanation of Solution

The structure for the given condensed structural formula, $\text{C}{\text{H}}_{\text{3}}\text{C}{\text{H}}_{\text{2}}\text{C}{\text{H}}_{\text{2}}\stackrel{\stackrel{\text{O}}{\parallel }}{\text{C}}-\text{OH}$ is drawn by showing the carbon numbers including the carboxyl carbon.

In the given compound, the parent carbon chain has four carbon atoms including the carboxyl carbon. These carbons are numbered from the carboxyl carbon from 1 to 4 as shown in the above structure. The given carboxylic acid compound is saturated because it constains only carbon-carbon single bonds Hence, the complete IUPAC name for the given compound is $\text{butanoic acid}$.

The given name is $\text{butanoic acid}$ which is correct to the condensed structure. Therefore, the given name for the structure is correct.