Stearyl palmitate is a saturated wax ester formed by esterification of palmitic acid (C16:0) with stearyl alcohol (C18H37OH), bridging the simple wax lipid series between cetyl stearate and behenyl behenate. This vegetable-derived emollient from palm/coconut sources delivers balanced chain asymmetry (C16 acid/C18 alcohol) for optimal texture control in anhydrous formulations.
Chemical Structure
Stearyl palmitate has the molecular formula C34H68O2 and a molecular weight of 508.90 g/mol. Its structure— CH3(CH2)14COO(CH2)16CH3—exhibits 32 rotatable bonds, no hydrogen bond donors, TPSA 26.3 Ų, and XLogP3 ~16.3. These characteristics enable the formation of stable β-crystalline lamellae through optimized van der Waals interactions between the C16/C18 hydrocarbon chains.
Physical Properties
Stearyl palmitate appears as white crystalline flakes or powder with a melting point of 59°C, a predicted boiling point of ~528°C, and a density of 0.857 g/cm³. It is insoluble in water but soluble in chloroform, slightly soluble in methanol, and readily soluble in hot oils or ethanol. Its low vapor pressure and HLB value of ~10 support emulsification performance. For optimal stability, storage at 2–8°C is recommended.
Synthesis and Production
Stearyl palmitate is produced via acid- or lipase-catalyzed condensation of palmitic acid and stearyl alcohol, followed by purification through distillation to achieve >99% purity. Its vegetable origin ensures a sustainable alternative compared to marine-derived cetyl esters, making it suitable for modern cosmetic and formulation applications.
