Question

Draw structural formulas for possible isomers of dichlorinated propane, \(\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{Cl}_{2}\) Name each compound.

Short answer

The isomers are 1,3-dichloropropane, 1,2-dichloropropane, and 1,1-dichloropropane.

Step-by-step solution

Understand the Parent Structure

The parent hydrocarbon structure we are working with is propane (\(\mathrm{C}_3\mathrm{H}_8\)). It is a three-carbon straight chain like this: \(-\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{CH}_3-\). Since we are dealing with isomers, we will substitute two hydrogen atoms with chlorine atoms at different positions to create different molecules.

Substitute Chlorines at Terminal Positions

Begin by substituting chlorines at the first and third carbon atoms (1,3-position). This creates a structure: \(\mathrm{CH}_2\mathrm{Cl}-\mathrm{CH}_2-\mathrm{CH}_2\mathrm{Cl}\). The IUPAC name for this compound is 1,3-dichloropropane.

Substitute Chlorines at 1,2-Position

Now place one chlorine on the first carbon and the second chlorine on the second carbon. The resulting structure: \(\mathrm{CH}_2\mathrm{Cl}-\mathrm{CHCl}-\mathrm{CH}_3\). The IUPAC name for this molecule is 1,2-dichloropropane.

Substitute Chlorines at 1,1-Position

Finally, place both chlorine atoms on the first carbon atom, resulting in: \(\mathrm{CHCl}_2-\mathrm{CH}_2-\mathrm{CH}_3\). This compound is named 1,1-dichloropropane.

Key concepts

Dichloropropane

Dichloropropane refers to a group of chemical compounds that are derived from propane by substituting two hydrogen atoms with chlorine atoms. This results in molecules that have the chemical formula \( \mathrm{C}_3\mathrm{H}_6\mathrm{Cl}_2 \). These chemicals are known for their application in organic synthesis and industrial uses.
Each form of dichloropropane is considered an isomer. Isomers have the same molecular formula but differ in the arrangement of atoms. Understanding isomers is crucial as it directly impacts the chemical properties and uses of the substance in question. For example, each isomer of dichloropropane can have different physical and chemical properties, making them suitable for varied applications.

Organic Chemistry

Organic chemistry is a branch of chemistry that focuses on compounds mainly composed of carbon and hydrogen atoms, often referred to as hydrocarbons. Propane, the parent compound for dichloropropane, is a small hydrocarbon containing only three carbon atoms and eight hydrogen atoms. This makes it an alkane—a type of saturated hydrocarbon.
In organic chemistry, the substitution of hydrogen atoms with other atoms, such as chlorine, leads to different compounds, known as halogenated hydrocarbons. Dichloropropane is a halogenated derivative of propane, and studying such derivatives helps chemists understand reactivity patterns and synthesis pathways.
Organic chemistry's principles guide us in predicting possible isomer structures and their name based on their atomic arrangement.

IUPAC Naming

The IUPAC system is a standard method for naming chemical compounds, ensuring that each compound has a unique and universally understood name. In IUPAC naming, the position of different atoms or groups in a molecule is important.
For dichloropropane, different isomers are named based on where the chlorine atoms are situated relative to the carbon chain:

• 1,1-Dichloropropane: Both chlorine atoms are on the first carbon atom.
• 1,2-Dichloropropane: Chlorine atoms are on the first and second carbon atoms.
• 1,3-Dichloropropane: Chlorine atoms are positioned on the first and third carbon atoms.

The numbers in these names indicate the specific carbon atoms the chlorine has replaced hydrogen on, helping distinguish between different isomers.

Structural Formulas

Structural formulas provide a clear way to represent the arrangement of atoms within a molecule, showing the connectivity between atoms. For dichloropropane, structural formulas help visualize where chlorine atoms replace hydrogen atoms on the propane chain.
In a 1,3-dichloropropane structure, you can visualize chlorine on each end of a three-carbon chain, implying a straight chain arrangement. For 1,2-dichloropropane, chlorine atoms sit on consecutive carbon atoms, indicating a substitution along the main skeletal chain. Lastly, in 1,1-dichloropropane, two chlorine atoms are bonded to the same carbon, presenting a unique atom cluster.
Using structural formulas is essential when studying organic molecules because it clarifies the molecules' potential chemical behaviors based on their shape and atomic connectivity.