Below is a list of fatty acids, a class of lipids, commonly found in foods. These are saturated, monounsaturated, and polyunsaturated fatty acids. For each acid, we have specified its common name, IUPAC name, and shorthand notation.
In the shorthand notation, the first number indicates the number of carbon atoms present in the molecule, whereas the second indicates the number of double bonds in the carbon chain. Note that this specific type of shorthand notation is not typically used for trans fatty acids.
In Summary: Key Points
- Chemical classification: fatty acids are classified into saturated, monounsaturated, and polyunsaturated fatty acids.
- Saturated fatty acids: containing no double bonds, they are highly stable and primarily found in animal fats like butter and lard, as well as in tropical oils like coconut and palm kernel oils.
- Monounsaturated fatty acids: containing one double bond, they are abundant in the Mediterranean diet.
- Polyunsaturated fatty acids: containing two or more double bonds, they include essential omega-3 and omega-6 families.
- Trans fatty acids: unsaturated fatty acids with at least one trans double bond.
| Type | Common name | IUPAC Name | Shorthand |
|---|---|---|---|
| Saturated fatty acids | Butyric acid | Butanoic acid | 4:0 |
| Caproic acid | Hexanoic acid | 6:0 | |
| Caprylic acid | Octanoic acid | 8:0 | |
| Capric acid | Decanoic acid | 10:0 | |
| Lauric acid | Dodecanoic acid | 12:0 | |
| Myristic acid | Tetradecanoic acid | 14:0 | |
| Palmitic acid | Hexadecanoic acid | 16:0 | |
| Stearic acid | Octadecanoic acid | 18:0 | |
| Arachidic acid | Icosanoic acid | 20:0 | |
| Behenic acid | Docosanoic acid | 22:0 | |
| Lignoceric acid | Tetracosanoic acid | 24:0 | |
| Monounsaturated fatty acids | Caproleic acid | Dec-9-enoic acid | 10:1n-1 |
| Lauroleic acid | (Z)-dodec-9-enoic acid | 12:1n-3 | |
| Myristoleic acid | (Z)-tetradec-9-enoic acid | 14:1n-5 | |
| Palmitoleic acid | (Z)-hexadec-9-enoic acid | 16:1n-7 | |
| Oleic acid | (Z)-octadec-9-enoic acid | 18:1n-9 | |
| Elaidic acid | (E)-octadec-9-enoic acid | – | |
| Vaccenic acid | (E)-octadec-11-enoic acid | – | |
| Gadoleic acid | (Z)-icos-9-enoic acid | 20:1n-11 | |
| Erucic acid | (Z)-docos-13-enoic acid | 22:1n-9 | |
| Brassidic acid | (E)-docos-13-enoic acid | – | |
| Nervonic acid | (Z)-tetracos-15-enoic acid | 24:1n-9 | |
| Polyunsaturated fatty acids | Linoleic acid | (9Z,12Z)-octadeca-9,12-dienoic acid | 18:2n-6 |
| alpha-Linolenic acid | (9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid | 18:3n-3 | |
| gamma-Linolenic acid | (6Z,9Z,12Z)-octadeca-6,9,12-trienoic acid | 18:3n-6 | |
| Columbinic acid | (5E,9E,12E)-octadeca-5,9,12-trienoic acid | – | |
| Stearidonic acid | (6Z,9Z,12Z,15Z)-octadeca-6,9,12,15-tetraenoic acid | 18:4n-3 | |
| Mead acid | (5Z,8Z,11Z)-icosa-5,8,11-trienoic acid | 20:3n-9 | |
| Dihomo-gamma-linolenic acid | (8Z,11Z,14Z)-icosa-8,11,14-trienoic acid | 20:3n-6 | |
| Arachidonic acid | (5Z,8Z,11Z,14Z)-icosa-5,8,11,14-tetraenoic acid | 20:4n-6 | |
| Eicosapentaenoic acid | (5Z,8Z,11Z,14Z,17Z)-icosa-5,8,11,14,17-pentaenoic acid | 20:5n-3 | |
| Docosapentaenoic acid | (7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoic acid | 22:5n-3 | |
| Docosahexaenoic acid | (4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoic acid | 22:6n-3 |
References
- Akoh C.C., Min D.B. Food lipids: chemistry, nutrition, and biotechnology. 4th Edition. Boca Raton: CRC Press, 2017. doi:10.1201/9781315151854
- Chow Ching K. Fatty acids in foods and their health implication. 3rd Edition. CRC Press, 2008.
- Soderberg T. Organic chemistry with a biological emphasis. Volume I. Chemistry Publications. 2019.
- Solomons T.W.G., Fryhle C.B., Snyder S.A. Solomons’ organic chemistry. 12th Edition. John Wiley & Sons Incorporated, 2017.
Domande Frequenti
What is the chemical difference between omega-3 and omega-6?
The difference lies in the position of the first carbon-carbon double bond from the methyl end. In omega-3 fatty acids, it is located at the third carbon atom, while in omega-6 it is at the sixth. This structure determines their biological pathways and functions.
How do you read the shorthand notation formula of a fatty acid?
Shorthand notation defines carbon atoms and double bonds. In the formula 18:3n-3, 18 represents the total number of carbon atoms, 3 is the number of double bonds, and n-3 indicates that the first double bond is located at the third carbon from the methyl end of the chain.
Why is IUPAC systematic nomenclature used for dietary fatty acids?
IUPAC naming provides a precise, globally standardized name that details the exact chemical structure. It defines the carbon chain length, the exact positions of double bonds, and whether their geometric configurations are in the natural cis or the trans form.