Cis–trans isomerism is also possible in molecules with rings. Draw the cis and trans isomers of 1,2-dimethylcyclohexane. In Exercise 41 , you drew all of the noncyclic structural and geometric isomers of C₄H₇F. Now draw the cyclic structural and geometric isomers of C₄H₇F.

Interpretation: The cis and trans isomers of 1 , 2 -dimethylcyclohexane and the cyclic structural and geometric isomers of C4H7F are to be drawn.

Concept introduction: Structural isomerism occurs when two compounds have same number of atoms but the spatial arrangement of the atoms is different from each other.  These isomers have the same formula but their properties are different. In cis-isomers, the substituents of the double bonded carbons are on the same side of the double bond but in trans isomer, they are on opposite side of double bond.

To determine: The cis and trans isomers of 1 , 2 -dimethylcyclohexane and the cyclic structural and geometric isomers of C4H7F .

Explanation

The Cis and trans isomers of 1,2-dimethylcyclohexane are given below.

The Cis isomer of 1,2-dimethylcyclohexane is,

Figure 1

The trans isomer of 1,2-dimethylcyclohexane is,

Figure 2

In the cis isomer, the two methyl groups are on the same side but in the trans isomer, they are opposite to each other.

The Cyclic structural isomer of C4H7F is 1 -florocyclobutane.

There are four carbon atoms, seven hydrogen atoms and one fluorine atom present in C4H7F . In 1 -florocyclobutane also, there are four carbon atoms, seven hydrogen atoms and one fluorine atom present. But their structures are different. Therefore, 1 -florocyclobutane is a structural isomer of C4H7F .

In 1 -florocyclobutane, the root word cyclobutane indicates the presence of a ring of four carbon atoms. Fluorine is attached to cyclobutane ring. Therefore, the structure of 1 -florocyclobutane is,

Figure 3

The cyclic structural isomer of C4H7F is 1 -(floromethyl)cyclopropane