Question

Name all the alcohols that have the formula \(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O} .\) How many ethers have the formula \(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O}\) ?

Short answer

There are 3 alcohols with the formula \(C_5H_{12}O\), which are 1-pentanol, 2-pentanol, and 3-pentanol. There are also 3 ethers with the formula \(C_5H_{12}O\), namely ethyl methyl ether, isopropyl methyl ether, and diethyl ether.

Step-by-step solution

Isomers for C5 Alcohols

To find the isomers of C5 alcohols having the formula C5H12O, we can attach the hydroxyl group (-OH) to different carbons: 1. Attach the -OH group to the first carbon: \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\) - This is 1-pentanol. 2. Attach the -OH group to the second carbon: \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}(\mathrm{OH})\mathrm{CH}_{2} \mathrm{CH}_{3}\) - This is 2-pentanol. 3. Attach the -OH group to the third carbon: \(\mathrm{CH}_{3} \mathrm{CH}(\mathrm{OH})\mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}\) - This is 3-pentanol. Naming all the alcohols, we have: 1-pentanol, 2-pentanol, and 3-pentanol.

Isomers for C5 Ethers

To find the isomers of C5 ethers having the formula C5H12O, we can connect the oxygen atom to different carbon atoms: 1. Connect the oxygen atom to two methyl groups: \(\mathrm{CH}_{3}\mathrm{O}\mathrm{CH}_{3}\) - This is dimethyl ether. However, it has the formula C2H6O, not C5H12O. So, this is not a valid option. 2. Connect the oxygen atom to a methyl group and an ethyl group: \(\mathrm{CH}_{3}\mathrm{O}\mathrm{C}_{2} \mathrm{H}_{5}\) - This is ethyl methyl ether. 3. Connect the oxygen atom to a methyl group and an isopropyl group: \(\mathrm{CH}_{3}\mathrm{O}\mathrm{CH}( \mathrm{CH}_{3}) \mathrm{CH}_{3}\) - This is isopropyl methyl ether. 4. Connect the oxygen atom to two ethyl groups: \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O} \mathrm{C}_{2} \mathrm{H}_{5}\) - This is diethyl ether. To answer the question, there are 3 alcohols having the formula C5H12O: 1-pentanol, 2-pentanol, and 3-pentanol. There are 3 ethers having the formula C5H12O: ethyl methyl ether, isopropyl methyl ether, and diethyl ether.

Key concepts

Alcohols

Alcohols are organic compounds that contain a hydroxyl group (-OH) attached to a carbon atom. This functional group is what defines alcohols and gives them unique properties. In the formula \( \mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O} \), alcohols are arranged such that the hydroxyl group can be placed on different carbon atoms, resulting in isomers. Isomers are compounds with the same molecular formula but different structural arrangements.

For a molecule like \( \mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O} \), we can create different alcohol isomers by varying the position of the (-OH) group:

• 1-Pentanol: Here, the (-OH) group is attached to the first carbon atom. Think of it like a long chain where the functional group is on one end.
• 2-Pentanol: In this case, the (-OH) is on the second carbon. This shifts the position slightly, creating a different molecule.
• 3-Pentanol: Now, the (-OH) is on the third carbon, providing yet another unique arrangement.

Understanding these different configurations helps in visualizing how small changes in structure can create distinct molecules with unique properties.

Ethers

Ethers are another class of organic compounds with the general formula \( \mathrm{R}-\mathrm{O}-\mathrm{R}' \), where \( \mathrm{R} \) and \( \mathrm{R}' \) are hydrocarbon groups connected by an oxygen atom. In the case of the molecular formula \( \mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O} \), ethers form isomers by varying the hydrocarbon groups connected to the oxygen. Here are the possible arrangements:

• Ethyl Methyl Ether: Combines a methyl group (\( \mathrm{CH}_{3} \)) with an ethyl group (\( \mathrm{C}_{2} \mathrm{H}_{5} \)). This gives a mix of short and long chains straddling the oxygen.
• Isopropyl Methyl Ether: Features a methyl group and an isopropyl group \( \mathrm{CH}( \mathrm{CH}_{3}) \mathrm{CH}_{3} \)). This creates a distinct branching at the isopropyl group.
• Diethyl Ether: Connects two ethyl groups (\( \mathrm{C}_{2} \mathrm{H}_{5} \)) with the oxygen, creating symmetry around the oxygen atom.

Ethers are well-known for their use as solvents and have different chemical behaviors than alcohols due to their structural differences.

Organic Chemistry Isomers

Isomers are fascinating in organic chemistry because they show how the same set of atoms can form entirely different compounds by rearranging their structure. In the context of \( \mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O} \), both alcohols and ethers exhibit isomerism.

_Isomers can be classified into different types:_

• Structural Isomers: These differ in how their atoms are connected. For alcohols and ethers, this might involve changing the carbon framework or the position of the (-OH) group or oxygen link.
• Stereoisomers: These involve different spatial arrangements but the same structural connections. This can occur in more complex molecules, where geometric or optical isomers become relevant.

Recognizing isomers requires practice and a good understanding of molecular structures. This understanding allows chemists to predict physical and chemical properties and how molecules interact in various environments. It's a core concept in organic chemistry that reveals the versatility and complexity of molecular structures.