Isopropyl Palmitate - Emollient Ester CAS 142-91-6

Isopropyl Palmitate (Isopropyl Palmitate) - Properties, Applications, and Safety

Isopropyl palmitate (CAS 142-91-6) is the ester of isopropyl alcohol and palmitic acid, a saturated fatty acid commonly derived from palm oil. It is a clear, colorless, and practically odorless liquid at room temperature, with a characteristic light, non-greasy feel. This ester is one of the most widely used emollients in the cosmetic and personal care industries, prized for its excellent spreadability, skin-conditioning properties, and ability to enhance the sensory profile of a wide range of products.

Chemical and Physical Properties

Isopropyl palmitate has the molecular formula C₁₉H₃₈O₂ and a molecular weight of approximately 298.5 g/mol. It is a lipophilic, low-viscosity liquid with a density of about 0.85 g/mL at 25°C and a refractive index of 1.436 to 1.440 at 20°C. Its melting point is in the range of 11-13°C and its boiling point is approximately 160°C at 2 mmHg. The compound has a flash point of 183°C, a cloud point of about 10°C, and an acid value of less than 0.5. It is highly soluble in oils, silicones, and organic solvents, but practically insoluble in water.

Mechanism of Action

As an ester, isopropyl palmitate acts primarily as an emollient and skin conditioning agent. It works by filling the spaces between skin cells, creating a smooth, soft, and flexible surface. Due to its low polarity and light molecular weight, it spreads rapidly and evenly on the skin without leaving a heavy or greasy residue. It reduces transepidermal water loss (TEWL) by forming a non-occlusive, breathable film on the skin's surface, which helps to maintain hydration while allowing the skin to function normally. As a non-comedogenic ingredient, it does not clog pores, making it suitable for use in facial care products, including those designed for acne-prone skin.

Applications

Isopropyl palmitate is a versatile, multi-functional ingredient with a wide range of applications.

Skin Care: It is a key component in moisturizers, body lotions, skin creams, sunscreens, and shaving creams. It provides a smooth, silky after-feel and improves the spreadability and absorption of active ingredients.

Hair Care: It is used in conditioners, shampoos, and hair treatment creams to add shine, improve manageability, and reduce static.

Color Cosmetics: It serves as a pigment binder, diluent, and solubilizer in lipsticks, foundations, makeup colors, and powders. It ensures even color distribution and smooth application.

Other Applications: It is also found in bath oils, antiperspirants, deodorants, pre-shave and aftershave products, and as a fragrance enhancer. Beyond cosmetics, it is used in pharmaceutical formulations as a penetration enhancer in topical drug delivery systems and as a component in microemulsions.

Safety and Toxicology

Isopropyl palmitate is considered a safe and well-tolerated ingredient for use in cosmetics and personal care products. The Cosmetic Ingredient Review (CIR) Expert Panel has concluded that it is safe as a cosmetic ingredient in current practices of use and concentration.

• Acute Toxicity: It has very low acute oral toxicity, with an LD50 in rats of greater than 5,000 mg/kg. It is also non-toxic via the dermal route.

• Skin and Eye Irritation: Undiluted isopropyl palmitate is considered a mild to moderate irritant, but formulations containing up to 45.6% have shown no signs of irritation or sensitization. It may cause mild eye irritation.

• Sensitization: It has been reported to be a weak potential sensitizer.

• Environmental Impact: The compound is readily biodegradable and is expected to rapidly biodegrade in aerobic soils and waters. In one study, 91.3% degradation was observed within 28 days. It is derived from renewable vegetable oils and is GMO-free.

Storage and Handling

Isopropyl palmitate should be stored in tightly sealed containers at 5–25°C, protected from light, moisture, and strong oxidizing agents. It is stable under normal storage conditions and has a long shelf life. Use appropriate personal protective equipment (gloves, safety goggles) when handling large quantities.

Conclusion

Isopropyl palmitate is a versatile, cost-effective, and safe emollient ester that plays a fundamental role in the formulation of modern cosmetic and personal care products. Its excellent spreadability, skin-conditioning properties, and non-comedogenic nature make it an indispensable ingredient for achieving desirable product textures and sensory experiences. With its favorable safety profile and ready biodegradability, it remains a preferred choice for formulators seeking both performance and sustainability.