Question

Draw all structural and geometrical (cis-trans) isomers of \(\mathrm{C}_{4} \mathrm{H}_{7} \mathrm{F}\) . Ignore any cyclic isomers.

Short answer

The three structural isomers of \(\mathrm{C}_{4}\mathrm{H}_{7}\mathrm{F}\) are: 1. 1-Fluoropropane: \(\mathrm{F\!-\!C_1 C_2 C_3 C_4}\) 2. 2-Fluoropropane: \(\mathrm{C_1 C_2\!-\!F C_3 C_4}\) 3. 1-Fluoro-2-methylpropane: \(\mathrm{F\!-\!C_1(C_2)C_3 C_4}\) Since none of these structures have double bonds or stereogenic centers, there are no cis-trans (geometrical) isomers for the given chemical formula.

Step-by-step solution

Find all possible arrangements of carbon atoms

To start, let's find all the possible ways to arrange our four carbon atoms. The different arrangements of carbon atoms can be: 1. As a straight chain: \(\mathrm{CCCC}\) 2. With a branch: \(\mathrm{CC(C)C}\)

Place the fluorine atom and hydrogen atoms

Now, let's place the fluorine atom and hydrogen atoms onto the carbon skeletons that we found in step 1. Arrangement 1: Straight chain \(\mathrm{CCCC}\) - 1-Fluoropropane: \(\mathrm{F\!-\!C_1 C_2 C_3 C_4}\) - 2-Fluoropropane: \(\mathrm{C_1 C_2\!-\!F C_3 C_4}\) Arrangement 2: With a branch \(\mathrm{CC(C)C}\) - 1-Fluoro-2-methylpropane: \(\mathrm{F\!-\!C_1(C_2)C_3 C_4}\)

Examine each arrangement for cis-trans (geometrical) isomers

Now, let's examine each of the structures we found in step 2 for geometrical (cis-trans) isomers. Since cis-trans isomerism occurs when there is restricted rotation around a double bond or when there is stereogenic center with a specific arrangement, we'll look for these features in each structure. - 1-Fluoropropane and 2-Fluoropropane: The structures have only single bonds, so there are no cis-trans isomers for these structures. - 1-Fluoro-2-methylpropane: This structure also has only single bonds, so there are no cis-trans isomers for this structure. As a result, since there are no structures with double bonds or stereogenic centers, we conclude that there are no cis-trans (geometrical) isomers for the given chemical formula.

List all found isomers

In this exercise, we found the following three structural isomers of \(\mathrm{C}_{4}\mathrm{H}_{7}\mathrm{F}\): 1. 1-Fluoropropane: \(\mathrm{F\!-\!C_1 C_2 C_3 C_4}\) 2. 2-Fluoropropane: \(\mathrm{C_1 C_2\!-\!F C_3 C_4}\) 3. 1-Fluoro-2-methylpropane: \(\mathrm{F\!-\!C_1(C_2)C_3 C_4}\) We've also determined that none of these structures have cis-trans (geometrical) isomers.

Key concepts

Structural Isomers

Structural isomers are fascinating because they allow the same set of atoms to form different molecules just by rearranging the connections between the atoms.
Understanding structural isomers involves recognizing that while the atoms remain the same, the connectivity can differ vastly, leading to distinct properties.In the case of hydrocarbons like \(\mathrm{C}_4\mathrm{H}_7\mathrm{F}\), structural isomers can exist due to how carbons connect to each other and to other atoms, such as fluorine in this case.
Here, we explored two main arrangements:

• Straight chain: Contains a linear sequence such as 1-Fluoropropane and 2-Fluoropropane.
• Branched chain: Contains a side branch, evident in compounds like 1-Fluoro-2-methylpropane.

By shifting the position of the fluorine and the arrangement of carbon atoms, we create distinct structural isomers, each showcasing different chemical and physical behaviors.
The key is recognizing potential variations in connecting the same set of atoms, emphasizing the creativity inherent in molecular chemistry.

Geometrical Isomers

Geometrical isomers introduce another layer of complexity and interest by involving a three-dimensional positioning difference but require more specific conditions to exist.
Commonly found in compounds with double bonds or rings, these isomers occur when there's restricted rotation, leading to different spatial arrangements around a bond.In the problem of \(\mathrm{C}_4\mathrm{H}_7\mathrm{F}\), we analyzed whether geometrical isomers exist. For geometrical isomerism, the presence of double bonds or a stereogenic center is crucial.
However, as we noticed with 1-fluoropropane, 2-fluoropropane, and 1-fluoro-2-methylpropane, these compounds only have single bonds and lack the necessary conditions for cis-trans isomerism.Without double bonds or the specific geometry required, geometrical isomers are not possible in this molecule. This exemplifies that while fascinating, geometrical isomerism's occurrence is highly condition-dependent, requiring specific structural features that were absent in this task.

Hydrocarbons

Hydrocarbons are the foundation of organic chemistry and include diverse families of compounds composed primarily of hydrogen and carbon atoms.
Their study underpins much of what we know about organic molecules and is crucial for understanding isomerism, as seen in \(\mathrm{C}_4\mathrm{H}_7\mathrm{F}\).This molecule belongs to a category characterized by organic frameworks altered by the addition of a fluorine atom, turning a typical hydrocarbon into a fluorinated version.
Such modifications change properties significantly and highlight the versatility of hydrocarbons:

• Alkanes: Saturated hydrocarbons with single bonds only, like the involved structures here.
• Functionalized Hydrocarbons: Such as 1-Fluoropropane, where slight changes in structure alter functionality and reactivity.

By understanding hydrocarbons, we develop an appreciation for their roles in more complex organic systems, and their part in forming the multitude of substances we encounter daily.
They serve as a reminder of the intricate and adaptable nature of chemical compounds.