Question

Write the structural formulas for all the branched-chain compounds with the molecular formula \(\mathrm{C}_{6} \mathrm{H}_{14}\).

Short answer

The five structural isomers of \(\mathrm{C}_{6} \mathrm{H}_{14}\) are hexane, 2-methylpentane, 3-methylpentane, 2,3-dimethylbutane, and 2,2-dimethylbutane.

Step-by-step solution

Understand the Molecular Formula

The molecular formula given is \(\mathrm{C}_{6} \mathrm{H}_{14}\), which indicates that the compound is an alkane with 6 carbon atoms and 14 hydrogen atoms. Alkanes are saturated hydrocarbons where each carbon has single bonds.

Identify the Straight-Chain Structure

Before looking at branched-chain structures, recognize that the straight-chain form of \(\mathrm{C}_{6} \mathrm{H}_{14}\) is hexane, with the continuous chain of six carbon atoms and all possible hydrogen surrounding them. Its structure will be used as a basis to find branched isomers.

Create Monobranched Isomers

Remove one carbon from the end of the straight chain and reposition it to form a branch. Create pentane as the main chain, then attach one carbon to form 2-methylpentane and 3-methylpentane.

Create Dibranched Isomers

To create dibranched isomers, remove two carbons and position them as two side chains. This results in 2,3-dimethylbutane, where the main chain is butane with branches at the 2nd and 3rd positions.

Explore All Possible Configurations

Continue rearranging the carbon atoms so you do not find any more unique isomers. Another valid configuration is 2,2-dimethylbutane, where both methyl groups are attached to the same carbon in the main butane chain.

Key concepts

Structural Isomers

In the world of organic chemistry, structural isomers hold a special place. These compounds have the same molecular formula, meaning they contain the same number and types of atoms, but their atoms are rearranged differently.
This different arrangement leads to a distinct structure and often different chemical properties. Consider isomers of alkanes like hexane, which is \(\mathrm{C}_6\mathrm{H}_{14}\). This molecule can exist in different forms as branched-chain alkanes or straight-chain alkanes.

• Each carbon atom can be connected in a variety of ways, such as single bonds forming different branch patterns.
• Even though the chemical formula remains the same, the structure varies.

This is what makes studying structural isomers fascinating and crucial in understanding organic molecules.

Alkanes

Alkanes are a fundamental group of hydrocarbons in organic chemistry, characterized by single bonds between carbon atoms.
The formula for alkanes can be represented as \(\mathrm{C}_n\mathrm{H}_{2n+2}\), where \(n\) represents the number of carbon atoms in the chain. This calculation shows an alkane is fully saturated with hydrogen.

• Alkanes are a part of many everyday substances, such as fuels and lubricants.
• They are the simplest form of hydrocarbons, which can be both straight-chained and branched.

Understanding alkanes provides a foundation to explore more complex organic molecules and their reactions.

Organic Chemistry

Organic chemistry is the branch of chemistry that focuses on carbon-based compounds, including their structure, properties, reactions, and synthesis.
Since carbon has the unique ability to form four covalent bonds, it leads to a variety of complex structures. This includes rings, chains, and branching molecules.

• It encompasses studying a wide range of molecules like alkanes, alkenes, and more complex organic entities.
• Organic chemistry is fundamental to the chemical industry, providing the basis for chemicals used in medicine, agriculture, and biotechnology.

The study of organic chemistry is like learning a new language, one spoken through the myriad forms and functions of carbon-based molecules.

Molecular Formula

A molecular formula is a simple representation that shows the number of each type of atom in a molecule.
In the case of \(\mathrm{C}_6\mathrm{H}_{14}\), it indicates there are 6 carbon atoms and 14 hydrogen atoms. This tells us it's an alkane due to the typical hydrogen-to-carbon ratio of \(\mathrm{H}_{2n+2}\).

• While the molecular formula gives us the number of atoms present, it doesn't reveal the structural arrangement.
• This means molecules with the same formula can exist as different isomers, leading to diverse physical and chemical properties.

Understanding molecular formulas is essential in deciphering the vast world of chemistry, allowing one to see beyond just numbers and into the structure and function of molecules.