Chapter 2, Problem 1PP

Practice Problem 2.1

Propose structures for two constitutional isomers of cyclopentene that do not contain a ring.

Interpretation Introduction

Interpretation:

The structuresfor two constitutional isomers of cyclopentene, which do not contain a ring, are to be proposed.

Concept introduction:

When two molecules have the same molecular formula, they are called isomers. If the connectivity of atoms is different, they are called constitutional isomers.

Constitutional isomers are the isomers in which the molecular formula remains the same but the arrangement of groups or atoms are different in structure.

In order to estimate the number of constitutional isomers of a particular compound, count the number of each atom and arranged all the atoms in different ways.

Answer to Problem 1PP

Solution:

Given: The structure of cyclopentene is as follows:

Explanation of Solution

The structure of cyclopentane contains 5 carbon atoms and 8 hydrogen atoms. Thus, the molecular formula of cyclopenteneis ${\text{C}}_{\text{5}}{\text{H}}_{\text{8}}$. Now, arrange the carbon and hydrogen atoms such that the molecular formula remains the same and the structure does not contain rings as follows:

The molecular formula is ${\text{C}}_{\text{5}}{\text{H}}_{\text{8}}$ but the connectivity of atoms is different.

Hence, the two constitutional isomers of ${\text{C}}_{\text{5}}{\text{H}}_{\text{8}}$ are as follows: