Question

Draw structural formulas for possible isomers with the formula \(\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{ClBr}\), and name each isomer.

Short answer

There are 4 structural isomers: 1-Chloro-2-bromopropane, 1-Bromo-2-chloropropane, 2-Chloro-1-bromopropane, 2-Bromo-1-chloropropane.

Step-by-step solution

Understand the Molecular Formula

The molecular formula is given as \(\text{C}_3\text{H}_6\text{ClBr}\). This means the compound contains 3 carbon atoms, 6 hydrogen atoms, 1 chlorine atom, and 1 bromine atom.

Identify the Isomer Types

The isomers with this formula can include both structural isomers and stereoisomers. However, due to the presence of different halogen atoms, we will focus on drawing only the structural isomers.

Draw the Parent Carbon Chain

Begin by drawing the possible parent carbon chains for this molecule. With 3 carbon atoms, the only possible chain is a propane chain: \(\text{C}_3\text{H}_7\).

Attach Halogens to the Carbon Chain

Now attach the halogens (Cl and Br) to different carbon atoms along the chain. Consider attaching them to C-1, C-2, and C-3 in all possible combinations.

Sketch Structural Isomers

Consider each unique position for Cl and Br on the propane chain: 1. 1-Chloro-2-bromopropane: Cl on C-1, Br on C-2 2. 1-Bromo-2-chloropropane: Br on C-1, Cl on C-2 3. 2-Chloro-1-bromopropane: Cl on C-2, Br on C-1 4. 2-Bromo-1-chloropropane: Br on C-2, Cl on C-1 For the above isomers, the positions on C-1 and C-2 result in different compounds due to the different halogens.

Confirm and Name the Isomers

Identify each distinct structure and assign names based on IUPAC naming conventions, taking into account the lowest locant rule for substituent positioning.

Key concepts

Structural Isomers

Structural isomers are compounds that have the same molecular formula but differ in the arrangements of their atoms. In such isomers, the connectivity between atoms varies, which means that even though they contain the same elements in the same quantities, their structures and properties can be quite different. For the formula \(\mathrm{C}_3\mathrm{H}_6\mathrm{ClBr}\), structural isomers can be made by moving the chlorine and bromine different positions on the propane chain. This change in attachment of halogens creates unique compounds with distinct names.

• The location of the halogens (Cl and Br) determines changes in the structure.
• The rearrangement results in various compounds like 1-chloro-2-bromopropane and 2-bromo-1-chloropropane.
• These distinct forms are not interchangeable unless chemical bonds are broken and reformed.

IUPAC Nomenclature

The International Union of Pure and Applied Chemistry (IUPAC) Nomenclature system is a standardized method for naming chemical compounds. It ensures that each compound has a unique name. The system uses a series of rules to provide a systematic way to name chemicals, making it easier for scientists to communicate accurately. When naming isomers such as those of \(\mathrm{C}_3\mathrm{H}_6\mathrm{ClBr}\), it follows a specific sequence.

• The longest carbon chain is identified first. For instance, in this case, it's the propane chain
• Number the carbon chain from the end closest to the halogen substituents to give them the lowest possible numbers.
• Prefix the halogen names with their positions such as "1-chloro-2-bromopropane" or "2-bromo-1-chloropropane".

These steps ensure that the compound's name provides information about the structure's nature and atom positioning.

Halogen Substitution

In organic chemistry, halogen substitution refers to the replacement or addition of halogen atoms to organic molecules. Halogens like chlorine (Cl) and bromine (Br) are common candidates in these substitutions due to their reactivity and the unique properties they impart on molecules. In \(\mathrm{C}_3\mathrm{H}_6\mathrm{ClBr}\), both Cl and Br serve as substituents replacing hydrogen atoms on the propane backbone.

• Halogen substitutes add new chemical characteristics to the compound.
• Substituting different positions creates different structural isomers.
• These structural changes affect the compound's physical and chemical properties like boiling points and reactivity.

Organic Chemistry

Organic chemistry is the branch of chemistry that studies carbon-based compounds, which include many elements like hydrogen, oxygen, nitrogen, and halogens such as chlorine and bromine. It's a field that explores the structure, properties, reactions, and synthesis of carbon compounds. The formula \(\mathrm{C}_3\mathrm{H}_6\mathrm{ClBr}\) is an example of an organic compound where the carbon atoms create the main structure, or skeleton, of the molecule.

• Organic compounds can form various structures including linear, branched, or cyclic forms.
• They can show phenomena like isomerism, which is crucial in creating diversity in organic molecules.
• Understanding organic chemistry is essential in fields like pharmaceuticals, petrochemicals, and materials science.