Question

Draw condensed structural formulas for the three ketones with the molecular formula \(\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}\).

Short answer

Answer: The condensed structural formulas for the three unique ketone structures are: 1. Structure 1: CH3C=OCH2CH2CH3 2. Structure 2: CH3C=OC(CH3)CH3 3. Structure 3: CH3CH2C=OCH2CH3

Step-by-step solution

Understanding ketones

Ketones are organic compounds containing a carbonyl group (\(\mathrm{C}=\mathrm{O}\)) bonded to two other carbon atoms. The general formula for a ketone is \(\mathrm{R}_{1} \mathrm{C}=\mathrm{O} \mathrm{R}_{2}\), where \(\mathrm{R}_{1}\) and \(\mathrm{R}_{2}\) are alkyl groups.

Identify possible ketone structures with \(\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}\) formula

Since we are given the molecular formula \(\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}\), we know that there are five carbon atoms, ten hydrogen atoms, and one oxygen atom present in the molecule. The oxygen atom is part of the carbonyl group, which is always connected to two carbon atoms. The remaining carbon and hydrogen atoms will form the alkyl groups \(\mathrm{R}_{1}\) and \(\mathrm{R}_{2}\). The position of the carbonyl group in the molecule will dictate the unique ketone structures.

Create the three unique ketone structures

There are three possible unique ketone structures that can be formed with the given molecular formula: 1. Ketone with the carbonyl group at the second carbon atom: \(\mathrm{CH}_{3}-\mathrm{C}=\mathrm{O}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\) (Structure 1) 2. Ketone with the carbonyl group at the second carbon atom, and the carbon chain having a branching at the third carbon atom: \(\mathrm{CH}_{3}-\mathrm{C}=\mathrm{O}-\mathrm{CH}(\mathrm{CH}_{3})-\mathrm{CH}_{3}\) (Structure 2) 3. Ketone with the carbonyl group at the third carbon atom, and the carbon chain being linear: \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{C}=\mathrm{O}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\) (Structure 3)

State the condensed structural formulas of the three ketones with the molecular formula \(\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}\)

The condensed structural formulas for the three unique ketone structures are: 1. Structure 1: \(\mathrm{CH}_{3}\mathrm{C}=\mathrm{O}\mathrm{CH}_{2}\mathrm{CH}_{2}\mathrm{CH}_{3}\) 2. Structure 2: \(\mathrm{CH}_{3}\mathrm{C}=\mathrm{O}\mathrm{C}(\mathrm{H}_{3})\mathrm{CH}_{3}\) 3. Structure 3: \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{C}=\mathrm{O}\mathrm{CH}_{2}\mathrm{CH}_{3}\)

Key concepts

Ketone Structure

In organic chemistry, understanding the ketone structure is crucial as ketones are a significant family of organic compounds. A ketone contains a distinctive functional group known as the carbonyl group, represented chemically as \( \text{C}=\text{O} \). This carbonyl carbon atom is directly bonded to two hydrocarbon groups, which are referred to as \( \text{R}_1 \) and \( \text{R}_2 \), forming a structure that can be observed in numerous ketone examples.
This specific structure gives ketones their unique chemical properties. For example, ketones generally exhibit distinct characteristics like a pleasant aroma, and they often serve as solvents in industrial applications. It's also worth noting that the location of the carbonyl group within the carbon chain can influence the behavior and reactivity of the ketone, making it important to fully grasp how this affects different ketone molecules.
When working with ketone molecules, remember that the carbonyl group cannot be located at the end of the carbon chain. This would instead result in an aldehyde rather than being classified as a ketone.

Molecular Formula

The molecular formula provides a snapshot showing the exact number and type of atoms present in a chemical compound. For ketones such as the ones given in this exercise, understanding and interpreting the molecular formula \( \mathrm{C}_5 \mathrm{H}_{10} \mathrm{O} \) is essential.
This formula indicates that in every molecule there are:

• Five carbon atoms (\( \mathrm{C}_5 \))
• Ten hydrogen atoms (\( \mathrm{H}_{10} \))
• One oxygen atom (\( \mathrm{O} \))

The formula is critical as it helps guide the determination of possible structural variations for the compound, which, in the case of ketones, must include a carbonyl group. The overall arrangement and connectivity of these atoms play a key role in defining the functional outcome and identity of the molecule.
Using molecular formulas, like \( \mathrm{C}_5 \mathrm{H}_{10} \mathrm{O} \), chemists can deduce not only the number of possible structural isomers but also understand how these structures might react differently under various conditions.

Condensed Structural Formula

A condensed structural formula is a compact way to represent the connectivity and arrangement of atoms within a molecule, particularly useful in organic chemistry. For ketones with a molecular formula of \( \mathrm{C}_5 \mathrm{H}_{10} \mathrm{O} \), representing these compounds with condensed formulas offers a clear illustration of their structure.
These formulas simplify the atom arrangements without requiring detailed line structures. For instance, the ketones in this exercise can be written as:

• \( \text{CH}_3\text{C}=\text{O}\text{CH}_2\text{CH}_2\text{CH}_3 \) for a linear chain ketone.
• \( \text{CH}_3\text{C}=\text{O}\text{C}(\text{H}_3)\text{CH}_3 \) for a branched ketone structure.
• \( \text{CH}_3\text{CH}_2\text{C}=\text{O}\text{CH}_2\text{CH}_3 \) showcasing a different position of carbonyl linkage.

Employing condensed structural formulas allows chemists to convey detailed structural information concisely. This makes it easier to identify and communicate the structural variety of isomers, thus aiding in discussions of reactivity and synthesis related to these organic compounds.