Chapter 21, Problem 55A

a.

Interpretation Introduction

Interpretation:

The name of the following structural formula needs to be determined:

${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$

Concept introduction:

The hydrocarbon compounds that contains single bond(s) between carbon atom(s) are said to be saturated hydrocarbon. Hydrocarbon compounds containing single bonds only are said to be alkane.

Answer to Problem 55A

Pentane.

Explanation of Solution

In order to give the name to the alkane following steps are followed:

1. The parent (longest) continuous carbon chain is identified.

2. The ending of the parent chain for alkane (-e) is -ane.

3. Name should be written in alphabetical order and numbering should be done in such a way that the substituent group gets lowest number.

4. Hyphen is used to connect the number to the name.

For number of carbons atoms in alkane chain, the prefix is given as:

Carbon-1    meth

Carbon-2    eth

Carbon-3    prop

Carbon-4    but

Carbon-5    pent

Carbon-6    hex

Carbon-7    hept

Carbon-8    oct

Carbon-9    non

Carbon-10    dec

The given structure is:

${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{3}}$

The parent chain contains 5 carbon as shown:

Since, the parent chain contains 5 carbon atoms and only single bonds are present so, the name of the compound is pentane.

b.

Interpretation Introduction

Interpretation:

The name of the following compound should be determined:

Concept introduction:

The ring structures of the compound having uncommon stability due to delocalized pi electron density shared in between all the carbon atoms of the ring is said to be an aromatic compound.

Answer to Problem 55A

1-ethyl-2, 3-dimethylbenzene.

Explanation of Solution

In order to give the name to the multiple substituted aromatic compounds, the following steps are followed:

1. For single substituted aromatic compound (when the substituent contains six or fewer carbons), the name of the substituted group is written first followed by the name of the aromatic compound.
2. For single substituted aromatic compound (when the substituent contains more than six carbons), the name of the aromatic compound is written first followed by the name of the substituted group.
3. For single substituted aromatic compound, the numbering on the ring is done in such a way that the multiple substituents get the lowest number.

The given structure is:

The given structure is trisubstituted substituted aromatic compound, benzene that contains two carbon chain, ethyl and 2 substituents as methyl so, numbering is done in a way:

Hence, the name of the compound is 1-ethyl-2, 3-dimethylbenzene.

c.

Interpretation Introduction

Interpretation:

The name of the following structural formula needs to be determined:

Concept introduction:

The hydrocarbon compounds that contains single bond(s) between carbon atom(s) are said to be saturated hydrocarbon. Hydrocarbon compounds containing single bonds only are said to be alkane.

Answer to Problem 55A

2, 5-dimethylhexane.

Explanation of Solution

The given structure is:

The parent chain contains 6 carbon atoms and 4 substituents so, the numbering is done as shown:

Since, the parent chain contains 6 carbon atoms and 2 methyl substituents at position 2 and 5 so, the name of the compound is 2, 5-dimethylhexane.

d.

Interpretation Introduction

Interpretation:

The name of the following structural formula needs to be determined:

Concept introduction:

The hydrocarbon compounds that contains single bond(s) between carbon atom(s) are said to be saturated hydrocarbon. Hydrocarbon compounds containing single bonds only are said to be alkane.

Answer to Problem 55A

2, 3-dimethylbutane.

Explanation of Solution

The given structure is:

The parent chain contains 4 carbon atoms and 2 substituents so, the numbering is done as shown:

Since, the parent chain contains 4 carbon atoms and 2 methyl substituents at position 2 and 3 so, the name of the compound is 2, 3-dimethylbutane.