Fatty Acid Nomenclature: Videos & Practice Problems

Fatty acid nomenclature is an essential aspect of understanding lipids, which are crucial biomolecules in biology. In this lesson, we focus on the different naming systems used for fatty acids, ensuring clarity in communication within the scientific community.

There are three primary systems for naming fatty acids: the common naming system, the systematic naming system, and the shorthand naming system. The common naming system includes names like oleic acid, which is widely recognized. In contrast, the systematic naming system uses a more formal approach, such as 9-octadecanoic acid, to describe the same fatty acid. This systematic method provides a clear structure based on the fatty acid's chemical composition and structure.

Additionally, the shorthand naming system is often preferred in academic settings, particularly in higher education. For example, the shorthand name for oleic acid is 18:1 Δ9, which indicates that the fatty acid has 18 carbon atoms and one double bond located at the ninth carbon from the carboxyl end. Understanding these naming conventions is vital for effective communication in biochemistry and related fields.

As we progress in our studies, we will delve deeper into the shorthand naming system, which is likely to be emphasized in your coursework. This foundational knowledge will prepare you for more complex topics, including isoprenes and other lipid-related structures.

Fatty acids can be systematically named using a shorthand naming system that involves a four-step process. This method allows for a clear and concise representation of the fatty acid's structure based on its carbon and double bond content.

The first step is to count the total number of carbon atoms in the fatty acid. For example, if a fatty acid has 18 carbon atoms, this number will be the first part of its shorthand name.

Next, the second step involves counting the total number of double bonds present in the fatty acid. If there are 2 double bonds, this will be the second part of the shorthand name. If there are no double bonds, this number would simply be 0.

In the third step, the two numbers are separated by a colon. For instance, with 18 carbon atoms and 2 double bonds, the shorthand representation would be written as 18:2.

The fourth step is only necessary if there are double bonds present. This step indicates the position of the double bonds using the Greek letter delta (Δ) with superscripts. The superscripts represent the lowest numbered carbon atoms that form each double bond. For example, if the first double bond starts at carbon 9 and the second at carbon 12, the shorthand would be written as 18:2Δ^9,12.

In summary, the complete shorthand name for a fatty acid with 18 carbon atoms and 2 double bonds located at carbons 9 and 12 is 18:2Δ^9,12. This specific fatty acid is commonly known as Linoleic acid. Understanding this naming system is essential for identifying and classifying fatty acids in biochemistry.