Stearyl stearate is a synthetic simple wax lipid formed by the esterification of stearic acid (C18:0) with stearyl alcohol (C18H37OH). This compound represents the archetypal fatty acid–long chain alcohol structure of waxes. Plant-derived and structurally homologous to cetyl palmitate but with extended C18 chains, it improves texture and stability in cosmetic formulations while providing superior lubricity compared with natural wax mixtures.
Chemical Structure
Stearyl stearate has the molecular formula C36H72O2 and a molecular weight of 536.96 g/mol. Its IUPAC name is octadecyl octadecanoate (CH3(CH2)16COO(CH2)17CH3). The linear ester contains 34 rotatable bonds, zero hydrogen-bond donors, a TPSA of 26.3 Ų, XLogP3-AA of 17.4, and a complexity index of 433, enabling tight lamellar β-crystalline packing typical of even-chain waxes.
Physical Properties
Stearyl stearate is a white to off-white waxy powder or flakes, with a melting point of approximately 62°C. Its predicted boiling point is 549°C, and its density is around 0.85 g/cm³. It is generally odorless with a mild fatty scent, insoluble in water, but soluble in hot ethanol, chloroform, acetone, and oils. Its high thermal stability (flash point >200°C) and low volatility make it suitable for melt-processing applications.
Biosynthesis and Industrial Synthesis
Industrially, stearyl stearate is produced through acid-catalyzed esterification of vegetable-derived stearic acid and stearyl alcohol, closely resembling enzymatic transesterification processes occurring in sebaceous glands. High-purity material (>99%) is typically obtained through distillation and advanced purification steps.
