Myristyl Stearate

What is the chemical structure of Myristyl Stearate?

Myristyl Stearate is an ester formed by the esterification of myristyl alcohol, a saturated 14-carbon fatty alcohol (C₁₄H₂₉OH), with stearic acid, a saturated 18-carbon fatty acid (C₁₇H₃₅COOH). The compound's formula is C₁₄H₂₉O-CO-C₁₇H₃₅, and it combines the hydrophobic characteristics of both parent molecules due to its classification as a fatty acid ester.

What are the physical and chemical properties of Myristyl Stearate?

Myristyl Stearate is typically a white, waxy solid at room temperature with a melting point of approximately 45-55°C, which may vary based on purity and isomer distribution. It is insoluble in water but soluble in oils, alcohols, and other non-polar organic solvents. Known for its stability against oxidation, it imparts a smooth, silky, and non-greasy feel in formulations.

How does Myristyl Stearate function in cosmetic products?

In cosmetics, Myristyl Stearate acts as an emollient, forming a protective lipid layer that reduces transepidermal water loss, enhancing hydration. It also serves as a thickening agent and texture enhancer, increasing the viscosity of formulations and providing a velvety, non-sticky finish. Additionally, it functions as a lubricant, reducing friction in topical applications like shaving creams and hair conditioners.

What applications are typical for Myristyl Stearate?

Myristyl Stearate is commonly used in cosmetics and skincare products such as moisturizers, makeup, and hair care products. Occasionally, it is employed as an excipient in pharmaceuticals or as a lubricant in industrial applications, including metalworking or polymer formulations due to its inert and non-irritating properties.

Is Myristyl Stearate safe for use on the skin?

Generally recognized as safe (GRAS) for topical use, Myristyl Stearate is non-irritating and non-sensitizing at typical concentrations (1-10%). However, it has a low to moderate comedogenic potential, meaning it could cause clogged pores in acne-prone skin. It complies with the FDA and EU Cosmetics Regulation and is biodegradable with low ecotoxicity.

How is Myristyl Stearate produced?

It is produced through acid-catalyzed esterification of myristyl alcohol and stearic acid at controlled temperatures (80-120°C). Catalysts such as sulfuric acid or enzymatic lipases facilitate the reaction, followed by purification processes to remove residual acids and alcohols.

What should formulators consider when using Myristyl Stearate?

Myristyl Stearate is compatible with most oils, waxes, and surfactants and can enhance emulsion stability by reducing phase separation. It is stable under typical cosmetic formulation pH ranges (pH 4-8) and doesn't require antioxidants due to its saturated structure. Nonetheless, it should be kept in airtight containers to avoid contamination and may need heating due to its limited solubility in polar solvents.

Are there alternatives to Myristyl Stearate?

Yes, alternatives such as cetyl stearate or isopropyl myristate offer similar emollient effects. Research is ongoing to optimize Myristyl Stearate's use in nanoemulsions and sustainable formulations.