Hydroxystearic Acid is  is a chemical compound, a fatty acid with a hydroxyl group attached.

The name describes the structure of the molecule:

• "Hydroxy". This part of the name indicates the presence of a hydroxyl (-OH) group in the molecule.
• "Stearic". This term refers to stearic acid, a saturated fatty acid with 18 carbon atoms.

Description of the raw materials used in production and their functions:

• Vegetable oil (like castor oil or soybean oil): These oils contain stearic acid, which can be hydrogenated to yield hydroxystearic acid.
• Oxidizing agents: Used to introduce hydroxyl groups (-OH) into the stearic acid molecule.

Step-by-step industrial synthesis:

Stearic acid is extracted from vegetable oils through processes like hydrolysis.

• Once isolated, the stearic acid undergoes an oxidation process, often using an oxidizing agent such as atmospheric oxygen.
• During oxidation, hydroxyl groups (-OH) are introduced into the stearic acid molecule, converting it to hydroxystearic acid.
• After oxidation, the product is purified through various methods to remove undesired impurities or by-products.

It appears in the form of a white powder. 

What it is for and where

Cosmetics

Cleansing agent. Ingredient that cleanses skin without exploiting the surface-active properties that produce a lowering of the surface tension of the stratum corneum. 

Surfactant - Emulsifying agent. Emulsions are thermodynamically unstable and are used to soothe or soften the skin and emulsify, so they need a specific, stabilising ingredient. This ingredient forms a film, lowers the surface tension and makes two immiscible liquids miscible. A very important factor affecting the stability of the emulsion is the amount of the emulsifying agent. Emulsifiers have the property of reducing the oil/water or water/oil interfacial tension, improving the stability of the emulsion and also directly influencing the stability, sensory properties and surface tension of sunscreens by modulating the filmometric performance.

Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surface-active action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities. 

Commercial Applications

Cosmetics. Hydroxystearic Acid is commonly used in cosmetic products as an emollient and stabilizer. It's found in creams, lotions, and lipsticks, helping to provide a smooth texture to the product.

Hair Care Products. It can be used in conditioners and hair treatments, offering conditioning properties.

Pharmaceutical. Hydroxystearic Acid can be employed in pharmaceutical formulations as an excipient and as a drug release modifier.

Chemical Industry. Hydroxystearic Acid is also used in the production of plasticizers, lubricants, and wax.

• Molecular Formula  C₁₈H₃₆O₃
• Molecular Weight  300.5 g/mol
• CAS  106-14-9
• UNII    933ANU3H2S
• EC Number   203-366-1
• DTXSID8026725
• Nikkaji  J48.641H

Synonyms:

• 12-Hydroxystearic acid
• Octadecanoic acid, 12-hydroxy-

References_____________________________________________________________________

Almeida M, Dudzinski D, Amiel C, Guigner JM, Prévost S, Le Coeur C, Cousin F. Aqueous Binary Mixtures of Stearic Acid and Its Hydroxylated Counterpart 12-Hydroxystearic Acid: Cascade of Morphological Transitions at Room Temperature. Molecules. 2023 May 25;28(11):4336. doi: 10.3390/molecules28114336. 

Delbecq F, Kaneko N, Endo H, Kawai T. Solvation effects with a photoresponsive two-component 12-hydroxystearic acid-azobenzene additive organogel. J Colloid Interface Sci. 2012 Oct 15;384(1):94-8. doi: 10.1016/j.jcis.2012.06.045.