Question

Draw the condensed structural formulas and give the IUPAC names of all the alcohols that have the formula \(\mathrm{C}_{5} \mathrm{H}_{12} \mathrm{O}\).

Short answer

The alcohols are Pentan-1-ol, Pentan-2-ol, Pentan-3-ol, 2-Methylbutan-1-ol, 3-Methylbutan-1-ol, 2-Methylbutan-2-ol, and 2,2-Dimethylpropan-1-ol.

Step-by-step solution

Understand the Molecular Formula

The molecular formula \(\text{C}_{5} \text{H}_{12} \text{O}\) indicates an alcohol with five carbon atoms, twelve hydrogen atoms, and one hydroxyl group (\text{OH}).

Identify all possible structures for \(\text{C}_{5} \text{H}_{12} \text{O}\)

Consider all possible ways to arrange five carbons with the \(OH\) group attached at different positions to make different alcohols.

Draw and name each structure

Draw each structure and provide the IUPAC name. This will include considering branched and unbranched chains.

Structure 1 - Pentan-1-ol

Structure: \(\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_2\text{CH}_2\text{OH}\) \(\text{IUPAC name: Pentan-1-ol}\)

Structure 2 - Pentan-2-ol

Structure: \(\text{CH}_3\text{CH}_2\text{CH}_2\text{CH}(\text{OH})\text{CH}_3\) \(\text{IUPAC name: Pentan-2-ol}\)

Structure 3 - Pentan-3-ol

Structure: \(\text{CH}_3\text{CH}_2\text{CH}(\text{OH})\text{CH}_2\text{CH}_3\) \(\text{IUPAC name: Pentan-3-ol}\)

Structure 4 - \text{2-Methylbutan-1-ol}

Structure: \(\text{CH}_3\text{CH}_2\text{CH}(\text{CH}_3)\text{CH}_2\text{OH}\) \(\text{IUPAC name: 2-Methylbutan-1-ol}\)

Structure 5 - \text{3-Methylbutan-1-ol}

Structure: \(\text{CH}_3\text{CH}(\text{CH}_3)\text{CH}_2\text{CH}_2\text{OH}\) \(\text{IUPAC name: 3-Methylbutan-1-ol}\)

Structure 6 - \text{2-Methylbutan-2-ol}

Structure: \(\text{CH}_3\text{CH}_2\text{C}(\text{OH})(\text{CH}_3)\text{CH}_3\) \(\text{IUPAC name: 2-Methylbutan-2-ol}\)

Structure 7 - \text{2,2-Dimethylpropan-1-ol}

Structure: \(\text{(CH}_3)_2\text{CCH}_2\text{OH}\) \(\text{IUPAC name: 2,2-Dimethylpropan-1-ol}\)

Key concepts

structural formulas

Understanding structural formulas is key in organic chemistry. A structural formula shows the arrangement of atoms within a molecule. In this exercise, the molecular formula \(\text{C}_{5} \text{H}_{12} \text{O}\) helps us identify the number of each type of atom. But to find all possible alcohols, we need to draw different ways in which the five carbon atoms can connect. Doing so, we also have to place the hydroxyl group (\(\text{OH}\)) at different positions.

For example, in pentan-1-ol, the hydroxyl group is attached at the end of a straight carbon chain. In contrast, in 2-methylbutan-2-ol, the hydroxyl group is linked to the second carbon of a branched chain. By drawing these variations, we arrive at different structural formulas. Each shows unique ways carbon and hydrogen atoms bond along with the hydroxyl group.

IUPAC nomenclature

IUPAC nomenclature ensures every chemical compound has a distinct and understandable name. For alcohols with the formula \(\text{C}_{5} \text{H}_{12} \text{O}\), we derive names based on specific rules.

First, identify the longest carbon chain containing the hydroxyl group. This chain's length as a prefix (pentan- for 5 carbons). Next, denote the position of the hydroxyl group using the lowest possible number.

In cases of branches, assign numbers to each carbon, ensuring the smallest set of locants for substituents. Example: 2-methylbutan-1-ol indicates a four-carbon chain with a methyl branch. The hydroxyl connects at carbon one. By following these steps, we generate IUPAC names like pentan-1-ol, pentan-2-ol, etc., ensuring clarity in chemical communication.

organic chemistry

Organic chemistry focuses on carbon-containing compounds. Alcohols, like those with formula \(\text{C}_{5} \text{H}_{12} \text{O}\), showcase the diversity in organic molecules, differing only by carbon connectivity and hydroxyl placement.

Organic chemists often examine structural isomers, molecules with the same molecular formula but different structures. In this exercise, we see several isomers, each a unique alcohol.

• Pentan-1-ol, with a straight chain.
• 2,2-Dimethylpropan-1-ol, with branched chains.
• 3-Methylbutan-1-ol, positioning the hydroxyl group differently.

This variety exemplifies organic chemistry's complexity and the importance of precise structural formulas and IUPAC names. Mastering these principles equips us to understand and predict the behavior of countless organic compounds.