Understanding the C22 Fatty Acid
Behenic Acid: The Common Name
The fatty acid C22, chemically represented as C22:0, is most commonly known as behenic acid. The 'C22' notation indicates that the molecule has a backbone of 22 carbon atoms. The ':0' signifies that there are no double bonds in the carbon chain, making it a saturated fatty acid. This long, straight-chain structure gives it its distinct physical properties, including its solid, wax-like consistency at room temperature.
Docosanoic Acid: The Systematic Name
In scientific contexts, particularly chemistry and biology, the IUPAC (International Union of Pure and Applied Chemistry) systematic name is preferred. For the C22 saturated fatty acid, the systematic name is docosanoic acid. This name is derived from the Greek root 'docosa' for 22, and 'anoic acid' for the saturated carboxylic acid functional group. Both names, behenic acid and docosanoic acid, refer to the exact same molecule (C${22}$H${44}$O$_{2}$).
Where is Behenic Acid Found?
Behenic acid is naturally present in several plant-based sources. It is particularly abundant in:
- Ben oil: This oil, extracted from the seeds of the moringa oleifera tree, contains a high percentage of behenic acid, from which the name 'behenic' was derived.
- Rapeseed (Canola) oil: While modern canola oil varieties have been bred to have low levels of erucic acid, behenic acid is still a minor component.
- Peanut oil and skins: Peanuts are another source where this fatty acid can be found.
- Certain animal fats: Behenic acid is also present in trace amounts in some animal fats.
Applications in Industry and Health
The unique properties of behenic acid make it valuable for various industrial and commercial uses. Its high stability and consistency are highly sought after, especially in cosmetics and personal care products.
Cosmetic Applications:
- Conditioning agent: It is frequently used in hair conditioners and moisturizers to provide smoothing and emollient properties.
- Thickening and opacifying agent: Behenic acid helps to thicken lotions, creams, and makeup, improving their texture and stability.
Industrial Applications:
- Lubricant: Its lubricating properties are useful in various industrial processes.
- Paint remover retarder: It can be used to slow down the evaporation of solvents in paint removers.
Potential Health Concerns: While used commercially, as a dietary component, behenic acid has been shown to raise cholesterol levels in humans, despite being poorly absorbed by the body compared to other fatty acids. For this reason, it is not considered a healthy substitute for other fatty acids in manufactured foods.
Comparison Table: Behenic Acid vs. Other C22 Fatty Acids
The C22 fatty acid family is not limited to just behenic acid. The presence or absence of double bonds and their positioning creates different molecules with different properties. Here is a comparison:
| Feature | Behenic Acid (C22:0) | Erucic Acid (C22:1) | Docosapentaenoic Acid (DPA, C22:5) |
|---|---|---|---|
| Saturation | Saturated | Monounsaturated | Polyunsaturated |
| Common Sources | Ben oil, canola oil, peanuts | Rapeseed, mustard oil | Fish oil, algae |
| Omega Designation | N/A | Omega-9 | Omega-3 or Omega-6 |
| Properties | Wax-like solid, used as a thickener and moisturizer. | Liquid, can raise cholesterol at high dietary levels. | Liquid, beneficial for brain and heart health. |
| Primary Use | Cosmetics, industrial lubricants | Low erucic acid versions are used for cooking oils. | Dietary supplement for cognitive and cardiovascular health. |
The Chemistry Behind the Name
To fully appreciate what is the name of the fatty acid C22, it helps to understand the underlying chemistry. A fatty acid is essentially a carboxylic acid with a long aliphatic chain. The length of this chain and the presence of double bonds determine its classification and properties. In the case of behenic acid, the 22-carbon chain is fully saturated, meaning it contains only single bonds. This makes it a very stable and non-reactive molecule, which is ideal for its use as an emulsifier and thickener in cosmetics. The systematic name, docosanoic acid, follows the IUPAC nomenclature rules: 'docos' for 22, 'an' for saturated, and 'oic acid' for the carboxylic acid group.
Conclusion
In summary, the fatty acid C22 is known by two main names: the common name behenic acid and the systematic name docosanoic acid. It is a long-chain saturated fatty acid found naturally in certain plant-based oils and utilized primarily in the cosmetic and industrial sectors for its stabilizing and textural properties. While it can have cholesterol-raising effects if consumed in high amounts, it is a versatile ingredient in many non-dietary products.
For more information on the chemical properties of behenic acid, consult the PubChem database from the National Institutes of Health.
