Chapter 21, Problem 71A

Interpretation Introduction

Interpretation:

The condensed structural formula for four different isomers of molecular formula, ${\text{C}}_4{\text{H}}_8$ should be drawn.

Concept introduction:

The molecules having same molecular formula but structural arrangement of atoms in the molecule is different are said to be isomers of each other.

Answer to Problem 71A

Isomer I:

Isomer II:

Isomer III:

Isomer IV:

Explanation of Solution

The given molecular formula is ${\text{C}}_4{\text{H}}_8$ which can be written in general formula as ${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$ where the value of n is 4 as per the given molecular formula. Since,

${\text{C}}_{\text{n}}{\text{H}}_{\text{2n}}$ is the general formula for alkene and cycloalkane so, the condensed structural formulas can be drawn as:

1. All four-carbon atoms are written in a straight chain and double bond at first position.

Isomer I:



2. All four-carbon atoms are written in a straight chain and double bond at second position.

Isomer II:



3. Making a three-carbon atoms straight chain with a double bond at position 1 and a methyl substituent at second carbon atom:

Isomer III:



4. Making a cycloalkane of four carbon atoms bonded by single bonds only:

Isomer IV: