Question

Draw the structural formulas for four structural isomers of \(\mathrm{C}_{4} \mathrm{H}_{9} \mathrm{Br} .\)

Short answer

There are four isomers of \( \mathrm{C}_4 \mathrm{H}_9 \mathrm{Br} \): 1-bromobutane, 2-bromobutane, 1-bromo-2-methylpropane, and 2-bromo-2-methylpropane.

Step-by-step solution

Understand Isomerism

Isomers are compounds with the same molecular formula but different structural formulas. We'll focus on the structural isomers of \( \mathrm{C}_4 \mathrm{H}_9 \mathrm{Br} \), meaning each isomer has a different arrangement of atoms. There are two main types of structural isomers to consider here: chain isomers and positional isomers.

Identify the Parent Structure

For \( \mathrm{C}_4 \mathrm{H}_9 \mathrm{Br} \), the parent hydrocarbon is a four-carbon alkane, which can be either straight (butane) or branched (isobutane).

Key concepts

Understanding Isomerism

Isomerism is a fascinating concept in organic chemistry, where compounds have the same molecular formula but exhibit different structures or arrangements of atoms. This crucial property allows for a remarkable diversity in organic compounds, even with the same number of atoms and types of elements. The structural variety arises because the atoms are connected differently, leading to unique properties and characteristics for each isomer. When discussing isomerism, it's important to note that we are referring to structural isomers, which have the same molecular formula but different connectivity between atoms.

In our exercise, the focus is on structural isomers of the compound with molecular formula \( \mathrm{C}_4 \mathrm{H}_9 \mathrm{Br} \). Here, the difference lies in how the Br (bromine) atom is attached, as well as the branching of the carbon chain. By understanding these variations, we can systematically approach drawing each isomer.

Exploring Structural Isomers

The term "structural isomers" refers to one of the key types of isomerism where compounds with the same molecular formula differ in how atoms are bonded together. These isomers can be entirely different in terms of their chemical and physical properties, such as boiling points, melting points, and chemical reactivity, despite sharing the same atomic composition.

For \( \mathrm{C}_4 \mathrm{H}_9 \mathrm{Br} \), we have two main types to consider:

• Chain isomers: These revolve around the different ways of arranging the carbon backbone. By varying the carbon chain as either straight (like butane) or branched (like isobutane), we create different chain isomers.
• Positional isomers: These isomers differ in the position of the bromine atom along the carbon chain. By altering bromine's position on the same carbon backbone, we obtain different isomers.

Being able to see how these changes affect the structural frameworks provides insights into why each isomer behaves uniquely.

Hydrocarbons in Organic Chemistry

Hydrocarbons are the simplest organic compounds, consisting solely of carbon and hydrogen atoms. They form the foundation of organic chemistry and play crucial roles as fuels and raw materials in various chemical processes. There are several types of hydrocarbons, characterized by the nature of bonds between the carbon atoms:

• Alkanes: These are saturated hydrocarbons, meaning all carbon-carbon bonds are single bonds. They have the general formula \( \mathrm{C}_n \mathrm{H}_{2n+2} \) and are known for being relatively unreactive compared to other organic groups.
• Alkenes: These unsaturated hydrocarbons have at least one carbon-carbon double bond, represented by the formula \( \mathrm{C}_n \mathrm{H}_{2n} \).
• Alkynes: Containing a carbon-carbon triple bond, their general formula is \( \mathrm{C}_n \mathrm{H}_{2n-2} \).

For our purpose, the parent compound \( \mathrm{C}_4 \mathrm{H}_9 \mathrm{Br} \) is derived from butane, a four-carbon alkane.

What are Alkanes?

Alkanes are a fundamental class of organic molecules that are integral to understanding organic chemistry basics. They are made up entirely of carbon (C) and hydrogen (H) atoms, linked together with single covalent bonds. Alkanes are often referred to as "saturated" hydrocarbons, because they hold the maximum number of hydrogen atoms possible—hence "saturated"—without any double or triple bonds.

The structure of alkanes can be straight-chain or branched, influencing their physical and chemical properties. For example, butane (\( \mathrm{C}_4 \mathrm{H}_{10} \)) is a straightforward chain alkane, while isobutane is a branched variant. The main feature of alkanes is their lack of significant chemical reactivity, making them stable under normal conditions. This stability makes them very useful as fuels, like propane in grills and butane in lighters. Understanding alkanes is crucial, as they serve as a foundation to delve deeper into the topic of structural isomers in more complex hydrocarbons.