Isotridecyl Stearate
[CAS 31565-37-4]

Identification

• Classification: Organic raw materials >> Carboxylic compounds and derivatives >> Carboxylic esters and their derivatives
• Name: Isotridecyl Stearate
• Synonyms: 11-methyldodecyl octadecanoate
• Molecular Formula: C₃₁H₆₂O₂
• Molecular Weight: 466.82
• CAS Registry Number: 31565-37-4
• EC Number: 250-703-3
• SMILES: CCCCCCCCCCCCCCCCCC(=O)OCCCCCCCCCCC(C)C

Properties

• Density: 0.9±0.1 g/cm³ Calc.^*
• Boiling point: 489.8±13.0 °C 760 mmHg (Calc.)^*
• Flash point: 255.5±9.7 °C (Calc.)^*
• Index of refraction: 1.454 (Calc.)^*

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

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H335
• Safety Statements: P261-P264-P270-P271-P280-P301+P312-P302+P352-P304+P340-P305+P351+P338-P330-P332+P313-P337+P313-P362-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	5	H303

Discovery and Applications

Isotridecyl stearate is a long-chain fatty acid ester formed from stearic acid and isotridecyl alcohol. It belongs to the broad class of alkyl stearates, which are commonly used in cosmetic, personal care, and industrial formulations due to their emollient properties, lubricity, and ability to modify texture in lipid-based systems. The compound is not a naturally occurring lipid but is produced through chemical esterification of fatty acids and branched-chain alcohols derived from petrochemical or oleochemical sources.

The development of fatty acid esters such as isotridecyl stearate is closely tied to the growth of industrial lipid chemistry and cosmetic formulation science during the twentieth century. As demand increased for synthetic emollients and skin-conditioning agents with improved stability and tailored sensory properties, chemists explored a wide range of esterification products derived from naturally abundant fatty acids like stearic acid. Stearic acid, a saturated C18 fatty acid widely found in animal fats and vegetable oils, became a key building block for such derivatives.

Isotridecyl alcohol, the other component of isotridecyl stearate, is a branched-chain fatty alcohol typically produced through industrial oligomerization processes that generate mixtures of C13 alcohol isomers. The branched structure of isotridecyl groups contributes to reduced crystallinity and improved spreadability compared with linear alcohol-derived esters. When esterified with stearic acid, this results in a compound with a balanced combination of hydrophobicity and fluidity, making it useful in topical formulations.

The synthesis of isotridecyl stearate is typically achieved through a condensation reaction between stearic acid and isotridecyl alcohol, often catalyzed by acidic catalysts under conditions that remove water to drive the esterification equilibrium. The resulting esterification product is purified to obtain a material suitable for industrial use. The ester bond formed in this reaction is stable under normal storage conditions but can be hydrolyzed under strong acidic or basic conditions to regenerate the parent fatty acid and alcohol.

One of the primary applications of isotridecyl stearate is in cosmetic and personal care formulations. Fatty acid esters are widely used as emollients, which function by forming a smooth, lubricating film on the skin surface. This helps reduce water loss and improves the sensory properties of creams, lotions, and ointments. The branched structure of isotridecyl stearate contributes to a lighter, less greasy feel compared with some linear esters, making it desirable in formulations designed for improved skin feel.

The compound is also used as a texture modifier in cosmetic systems. Its long hydrophobic chain allows it to interact with other lipid components in formulations, influencing viscosity, spreadability, and product stability. In emulsions, isotridecyl stearate can contribute to improved consistency and a more uniform application profile. These properties are important in the design of both leave-on and rinse-off personal care products.

In addition to cosmetic applications, isotridecyl stearate has uses in industrial formulations where lubricity and surface modification are required. Fatty acid esters can function as lubricants or lubricant additives due to their ability to reduce friction between surfaces. The chemical stability and hydrophobic nature of stearate esters make them suitable for use in a variety of non-aqueous systems.

The physicochemical properties of isotridecyl stearate are characteristic of high-molecular-weight esters, including low water solubility, relatively high boiling point, and a nonpolar nature. These properties arise from the long hydrocarbon chains present in both the fatty acid and alcohol components. The branched structure of the isotridecyl group reduces crystallization tendency, contributing to improved fluidity at room temperature compared with fully linear analogs.

Overall, isotridecyl stearate is a synthetic fatty acid ester primarily used as an emollient and texture-modifying agent in cosmetic and industrial formulations. Its importance lies in its ability to combine the lubricating properties of long-chain lipids with improved sensory characteristics derived from branching, making it a versatile ingredient in modern formulation chemistry.

References

2015. International Journal of Toxicology 34(Suppl.2):5-69. International Journal of Toxicology.
URL: https://www.epa.gov/chemical-data-reporting