Chapter 21: Problem 42

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 \(\mathbf{C}_{4} \mathrm{H}_{7} \mathrm{F}\). Now draw the cyclic structural and geometric isomers of \(\mathrm{C}_{4} \mathrm{H}_{7} \mathrm{F}\).

Short Answer

Expert verified

The cis and trans isomers of 1,2-dimethylcyclohexane can be visualized as follows: Cis isomer: ``` H2 H2 H2 (bond) (bond) H2 H2 H2 ``` Trans isomer: ``` H2 H2 H2 (bond)(bond) H2 H2 H2 ``` The possible cyclic structures for C4H7F are: 1. Fluoromethylcyclopropane or FCH2-C3H5: ``` F H2 (bond) H2 H2 ``` 2. 1-fluorocyclobutane or C4H7F: ``` F H2 H2 (bond) (bond) H2 H2 H2 H2 ```

Step by step solution

To draw the cis and trans isomers of 1,2-dimethylcyclohexane, we must first understand the structure of the molecule. Cyclohexane is a six-membered ring with two methyl (CH3) groups attached to its adjacent carbon atoms. In the cis isomer, both methyl groups are on the same side of the ring, while in the trans isomer, they are on opposite sides. The drawings should be as follows: Cis isomer: ``` H2 H2 H2 (bond) (bond) H2 H2 H2 ``` Trans isomer: ``` H2 H2 H2 (bond)(bond) H2 H2 H2 ``` #Step 2: Draw cyclic structural and geometric isomers of C4H7F#

First, we need to identify the possible cyclic structures for C4H7F. The simplest cyclic structure is the 3-membered ring named cyclopropane. As we have an F atom, the structures can be written as C3H6F, where the F atom replaces one H atom in the cyclopropane structure. We can also have a cyclobutane structure where F is attached to the carbon atom of the 4-membered ring, which could be expressed as C4H7F. Here are the possible cyclic structures: 1. Fluoromethylcyclopropane or FCH2-C3H5: ``` F H2 (bond) H2 H2 ``` 2. 1-fluorocyclobutane or C4H7F: ``` F H2 H2 (bond) (bond) H2 H2 H2 H2 ``` Keep in mind that since there are no double bonds in the cyclic structures, there is no possibility of cis-trans isomerism for these structures.