Chapter 21, Problem 61A

(a)

Interpretation Introduction

Interpretation:

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

Concept introduction:

The hydrocarbon compounds contain compound that are made up of only hydrogen and carbon atoms. Hydrocarbon compounds that contains multiple bond(s) are said to be unsaturated hydrocarbon. Compounds containing double bonds are said to be alkene whereas compounds containing triple bonds are said to be alkyne.

Answer to Problem 61A

2-methylbut-2-ene.

Explanation of Solution

In order to give the name to the unsaturated hydrocarbon, alkene following steps are followed:

1. The parent (longest) continuous carbon chain containing multiple bonds between the carbon atoms is selected.

2. While writing the name of alkene, the suffix “ane” of the corresponding alkane is replaced by “ene”.

3. Name should be written in alphabetical order and numbering should be done in such a way that the multiple bond and 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:

The parent chain in the given structure is of 4-carbon atoms so, prefix will be but. Numbering is done in such a way that the multiple bond that is double bond gets lower number that is 2. A methyl substituent is present at position 2. So,

So, the name of the compound is 2-methylbut-2-ene.

(b)

Interpretation Introduction

Interpretation:

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

Concept introduction:

The hydrocarbon compounds contain compound that are made up of only hydrogen and carbon atoms. Hydrocarbon compounds that contains multiple bond(s) are said to be unsaturated hydrocarbon. Compounds containing double bonds are said to be alkene whereas compounds containing triple bonds are said to be alkyne.

Answer to Problem 61A

2-ethylbut-1-ene.

Explanation of Solution

The given structure is:

The parent chain in the given structure is of 4-carbon atoms so, prefix will be but. Numbering is done in such a way that the multiple bond that is double bond gets lower number that is 1. An ethyl substituent is present at position 2. So,

So, the name of the compound is2-ethylbut-1-ene.

(c)

Interpretation Introduction

Interpretation:

The name of the following compound should be determined:

Concept introduction:

When the carbon atoms of hydrocarbons are arranged in such a way that it results in the formation of ring then it is said to be cycloalkanes.

Answer to Problem 61A

1-methylcyclopent-1-ene.

Explanation of Solution

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

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

2. The prefix -cyclo is used before the name of alkane for a ring.

3. If the attached alkyl chain possesses greater number of carbon atoms, then alkyl chain is considered as primary parent chain.

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

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

The given structure is:

The parent chain contains a ring of 5 carbon atoms with a double bond in the ring so, prefix will be pentene and 1 substituent so numbering is done in such a way that substituent and double bond gets lower number as shown:

So, the name of the compound is 1-methylcyclopent-1-ene.

(d)

Interpretation Introduction

Interpretation:

The name of the following compound should be determined:

Concept introduction:

When the carbon atoms of hydrocarbons are arranged in such a way that it results in the formation of ring then it is said to be cycloalkanes.

Answer to Problem 61A

3-methylcyclobut-1-ene.

Explanation of Solution

The given structure is:

The parent chain contains a ring of 4 carbon atoms with a double bond in the ring so, prefix will be butene and 1 substituent so numbering is done in such a way that substituent and double bond gets lower number as shown:

So, the name of the compound is 3-methylcyclobut-1-ene.