Chapter 19, Problem 60PE

(a)

Interpretation Introduction

Interpretation:

The given name for the alkyl chloride compound has to be cross-checked with its structure by applying the IUPAC rules. If it is incorrect, the correct name has to be  given.

Concept Introduction:

IUPAC rules for naming alkyl halides:

• Identify the parent carbon chain in the given compound. The halogens and 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 right end of the carbon chain as shown in the above structure. The chlorine substituent, $-\text{Cl}$ is identified on $\text{C-2}$ in the parent carbon chain. Hence, the complete IUPAC name for the given compound is $\text{2-chlorobutane}$.

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

(b)

Interpretation Introduction

Interpretation:

The given name for its condensed structural formula is 2-butaneketone has to be confirmed by applying the IUPAC rules.  If it is incorrect, the correct name has to be determined.

Concept Introduction:

IUPAC rules for naming ketones:

• Identify the parent carbon chain in the given compound that must contain the carbonyl functional group in it. If two or more chains have the same carbon lengths, choose the chain with a greater number of substituents bonded to it.
• The ketone IUPAC name is derived from the respective alkane. Thus, the parent compound name is obtained by replacing the $\text{-}e$ ending of the alkane to $\text{-}one$.
• If the parent carbon chain contains more than four carbons including the carbonyl carbon, the parent carbon chain is numbered from the end of the chain nearest to the ketone functional group.
• 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 which includes the carbonyl carbon. The parent carbon chain is numbered from the left end of the carbon chain as shown in the above structure. The ketone functional group is identified on $\text{C-2}$ in the parent carbon chain. Hence, the complete IUPAC name for the given compound is $\text{2-butanone}$.

The given name is $\text{2-butaneketone}$ which is incorrect to the given condensed structure because the suffix for the ketone functional is wrong. Therefore, the correct name is $\text{2-butanone}$.

(c)

Interpretation Introduction

Interpretation:

The given name for the unsaturated hydrocarbon of ${\text{CH}}_{\text{3}}{\text{CH=CH}}_{\text{2}}\text{CH}\left({\text{CH}}_{\text{3}}\right){\text{CH}}_{\text{3}}$ has to be confirmed by applying the IUPAC rules. If it is incorrect, the correct name has to be identified.

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 five carbons in the parent carbon chain. The given compound is unsaturated hydrocarbon because the parent carbon chain contains the carbon-carbon double bond between $\text{C-3}$ and $\text{C-4}$. So, the parent compound’s name is $\text{3-pentene}$. The parent carbon chain is numbered from the right 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 $\text{2-methyl-3-pentene}$.

The given name is $\text{2-methyl-3-pentene}$ which is correct to the condensed structure. Therefore, the given name for the structure is correct.

(d)

Interpretation Introduction

Interpretation:

The given name for the ester compound has to be validated with its condensed structural formula, ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\stackrel{\stackrel{\text{O}}{\parallel }}{\text{C}}{\text{OCH}}_{\text{3}}$ by applying the IUPAC rules. If it is incorrect, the correct name has to be determined.

Concept Introduction:

IUPAC rules for naming esters:

• Name the first part of the ester name as the $\text{R}$ (alkyl) group name of the $-\text{COOR}$ ester group.
• Name the second part of the ester name by replacing the $-icacid$ ending of the parent carboxylic acid with $-ate$.

Explanation of Solution

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

The first part of the ester name is $\text{methyl}$ because the alcohol portion contains only one carbon atom. The parent carbon chain is numbered from the carboxyl carbon as shown in the above structure. There are three carbons in the parent carboxylic acid portion. So, the second part of the ester name is $\text{propanoate}$. Hence, the complete IUPAC name for the given compound is $\text{methyl propanoate}$.

The given name is $\text{propyl methanoate}$ which is incorrect to the given condensed structure because the first part of the ester name is interchanged with the second part of the ester name. Therefore, the correct name is $\text{methyl propanoate}$.

(e)

Interpretation Introduction

Interpretation:

The given name for its condensed structural formula is verified by applying the IUPAC rules. If it is incorrect, the correct name is provided.

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 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 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 $\text{3-methylpentane}$.

The given name is $\text{2-ethylbutane}$ which is incorrect to the given condensed structure because the correct parent carbon chain has the five carbons. Therefore, the correct name is $\text{3-methylpentane}$.