Chapter 21, Problem 83A

(a)

Interpretation Introduction

Interpretation:

Whether the numbering of following structure is correct or not needs to be determined and if the numbering is wrong then the structure needs to be redrawn with correct numbering:

Concept introduction:

The hydrocarbon compounds contain compound that are made up of only hydrogen and carbon atoms.

The naming of the hydrocarbon compounds is done in such a way that substituents gets lower number.

Answer to Problem 83A

The numbering for the given compound is correct.

Explanation of Solution

The given compound is disubstituted cycloalkane, so the main group is cycloalkane since, the cycloalkane is made up of four carbon atoms so, it is named as cyclobutane and the numbering of the two methyl substituents is done in such a way that it gets lower number that is 1 and 2 so, the given numbering is correct and name of the compound is 1, 2-dimethylcyclobutane.

(b)

Interpretation Introduction

Interpretation:

Whether the numbering of following structure is correct or not needs to be determined and if the numbering is wrong then the structure needs to be redrawn with correct numbering:

Concept introduction:

The hydrocarbon compounds contain compound that are made up of only hydrogen and carbon atoms.

The naming of the hydrocarbon compounds is done in such a way that substituents gets lower number.

Answer to Problem 83A

The numbering for the given compound is incorrect. The correct numbering is:

Explanation of Solution

The given compound is alkyne, compound containing triple bond. The numbering in alkyne is done in such a way that the triple bond gets lower number so, the correct numbering will be:

Hence, the given numbering is incorrect and name of the compound is pent-2-yne.

(c)

Interpretation Introduction

Interpretation:

Whether the numbering of following structure is correct or not needs to be determined and if the numbering is wrong then the structure needs to be redrawn with correct numbering:

Concept introduction:

The hydrocarbon compounds contain compound that are made up of only hydrogen and carbon atoms.

The naming of the hydrocarbon compounds is done in such a way that substituents gets lower number.

Answer to Problem 83A

The numbering for the given compound is correct.

Explanation of Solution

The given compound is disubstituted cycloalkene, so the main group is cycloalkene since, the cycloalkene is made up of five carbon atoms so, it is named as cyclopentene and the numbering of the two methyl substituents is done in such a way that double bond gets the lowest possible number. Hence, the given numbering is correct and name of the compound is 1, 3-dimethylcyclopent-1-ene.

(d)

Interpretation Introduction

Interpretation:

Whether the numbering of following structure is correct or not needs to be determined and if the numbering is wrong then the structure needs to be redrawn with correct numbering:

Concept introduction:

The hydrocarbon compounds contain compound that are made up of only hydrogen and carbon atoms.

The naming of the hydrocarbon compounds is done in such a way that substituents gets lower number.

Answer to Problem 83A

The numbering for the given compound is correct.

Explanation of Solution

The given compound is disubstituted benzene, so the main group is benzene. The numbering of the two substituents that is ethyl and methyl is done in such a way it gets the lowest possible number. Hence, the given numbering is correct and name of the compound is written in alphabetical order as 1-ethyl-3-methylbenzene.