Question

Name the following alcohols using the IUPAC system. (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{2} \mathrm{CH}_{3}\) (b) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\)

Short answer

The IUPAC names of the given alcohols are Pentan-3-ol and Pentan-5-ol.

Step-by-step solution

First Compound Analysis

Start with the first compound \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{2} \mathrm{CH}_{3}\). Identify the longest continuous carbon chain and number the carbons in such a way that the carbon attached to the hydroxyl group (OH) gets the lowest possible number. Here, the carbon chain is five carbons long and the OH group is attached to the third carbon.

First Compound Naming

Use the right prefix for the carbon chain (pent- for 5 carbons), infix for the type of bond (an- for single bonds), and suffix for the functional group (ol for alcohols). Also, mention the position of the functional group. Hence, the IUPAC name is Pentan-3-ol.

Second Compound Analysis

Now move to the second compound \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}\). This compound also has five carbons in its longest chain and the OH group is attached to the last carbon.

Second Compound Naming

The IUPAC name using the right prefix, infix, and suffix with the position of the functional group is Pentan-5-ol.

Key concepts

Organic Chemistry

Organic chemistry is the study of carbon-containing compounds, nearly all of which contain hydrogen atoms along with other elements such as oxygen, nitrogen, sulfur, and halogens. Generally, these compounds are constructed upon carbon skeletons that allow for a myriad of functional group arrangements, contributing to the diverse nature of organic chemistry. When studying organic compounds, identifying the framework or backbone of carbon atoms is crucial since it determines the base name of the compound in systematic chemistry nomenclature.
In organic chemistry, specific rules and patterns are followed for naming compounds, especially when it comes to identifying significant features such as length of the carbon chain and identifying substituents. This leads to a structured approach like the IUPAC system (International Union of Pure and Applied Chemistry) to ensure consistency in naming across various scientific disciplines worldwide.

Functional Groups

Functional groups are specific atoms, ions, or groups of atoms within molecules that have characteristic chemical properties. These groups play a key role in determining the chemical behavior of the molecule they belong to. Alcohols represent one of many types of functional groups, characterized by the presence of an -OH group, also known as a hydroxyl group.
When identifying functional groups in organic compounds, it is important to locate them accurately in the molecular structure, as they dictate the chemical function and properties of the molecule. In our case study:

• The functional group is the -OH (hydroxyl group).
• It defines the compound's reactivity and its physical properties such as solubility in water.

Recognizing and naming functional groups correctly ensures clear communication in scientific discussions and documentation.

Alcohols

Alcohols are a class of organic compounds where one or more hydroxyl (-OH) groups are bound to a saturated carbon atom. These compounds are named in the IUPAC system by identifying the longest carbon chain attached to the hydroxyl group, followed by the suffix "-ol", denoting the alcohol functional group.
For example, in the structure

• the functional group (-OH) determines the compound is an alcohol and provides the suffix.
• The location of the hydroxyl group is indicated by a number, stating the carbon position in the chain to which it is attached, like Pentan-3-ol for the OH group on the third carbon of a five-carbon chain.

By following these IUPAC guidelines, the systematic naming of alcohols ensures clarity and reduces ambiguity in chemical identification and research.