Isooctadecanoic acid
[CAS# 30399-84-9]

Identification

• Classification: Food additive >> Nutrition supplements >> Fatty acids
• Name: Isooctadecanoic acid
• Synonyms: Isostearic acid; Isostearic acid 873; Isostearic acid EX; Jaric I 18CG; Jaric I 18IG; Prisorin ISAC 3505; Prisorine 3501; Prisorine 3502; Prisorine 3505; Prisorine 3508; UCN 96.319; Unimac 5680
• Molecular Formula: C₁₈H₃₆O₂
• Molecular Weight: 284.48
• CAS Registry Number: 30399-84-9
• EC Number: 250-178-0
• SMILES: CC(C)CCCCCCCCCCCCCCC(=O)O

Properties

• Density: 0.9±0.1 g/cm³, Calc.^*
• Melting point: 69.5 °C (Expl.)
• Index of Refraction: 1.455, Calc.^*
• Boiling Point: 400.8±13.0 °C (760 mmHg), Calc.^*
• Flash Point: 225.7±8.2 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315
• Safety Statements: P264-P280-P302+P352-P321-P332+P317-P362+P364

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315

Discovery and Applications

Isooctadecanoic acid, also known as 2-methylhexadecanoic acid, is a branched-chain fatty acid. This compound is a member of the long-chain fatty acids and is characterized by its branched structure, distinguishing it from the more common straight-chain fatty acids. It is primarily used in industrial applications, including in the manufacturing of lubricants, surfactants, and cosmetics.

The discovery of isooctadecanoic acid, like many fatty acids, can be traced to the broader study of lipids and fatty acids, which began in the 19th century. Although specific details of its initial discovery are not well-documented, the compound is a naturally occurring fatty acid found in small amounts in animal fats and vegetable oils. Its structure consists of a 16-carbon chain with a methyl group attached to the second carbon, making it a branched-chain fatty acid. This structure contributes to its distinctive physical and chemical properties compared to its straight-chain counterparts, such as stearic acid.

Isooctadecanoic acid is primarily used in the production of lubricants, where it serves as an additive to improve the lubricating properties of oils. The presence of the branched structure helps reduce friction, making it useful in various industrial applications where high-performance lubricants are required. It is also used in the production of surfactants, where it helps to modify the surface tension between liquids and solids, making it useful in cleaning products and emulsifiers.

In the cosmetics and personal care industry, isooctadecanoic acid is used in the formulation of creams, lotions, and other topical products. It functions as an emulsifier, helping to blend oils and water in cosmetic formulations. Additionally, its mildness and non-irritating properties make it suitable for sensitive skin care products.

Although isooctadecanoic acid is not as widely known as some other fatty acids, its unique structure and properties make it a valuable compound in specific industrial and consumer product formulations. Its ability to modify physical properties such as melting point and solubility due to its branched structure enhances the performance of products that incorporate it.

References

2023. Isostearic acid is an active component of imiquimod formulations used to induce psoriaform disease models. Inflammopharmacology, 31(3).
DOI: 10.1007/s10787-023-01175-3

2023. Chemical and biological evaluation of biosurfactant fractions from Wickerhamomyces anomalus CCMA 0358. Applied Microbiology and Biotechnology, 107(24).
DOI: 10.1007/s00253-023-12811-x

2023. Bioprospecting of biosurfactant-producing bacteria for hydrocarbon bioremediation: Optimization and characterization. Korean Journal of Chemical Engineering, 40(7).
DOI: 10.1007/s11814-023-1418-y