Cetyl dihydrogen phosphate

Cetyl dihydrogen phosphate (CAS 3539-43-3) is a monoester of phosphoric acid and cetyl alcohol, also known as hexadecyl phosphate or monocetyl phosphate and sold under trade names such as Amphisol A. It carries no assigned E-code and belongs to the phosphate ester surfactant class.

In cosmetic emulsions, the phosphate head group anchors to water while the C16 tail orients toward oil, stabilising oil-in-water systems and contributing mild thickening through electrostatic repulsion between droplets. In pharmaceutical topical formulations, it functions as an emulsifier and skin-conditioning agent, and in coatings it improves substrate wetting by reducing interfacial tension at pigment surfaces.

Cetyl dihydrogen phosphate is supplied in compliance with REACH registration requirements and is available in cosmetic and pharmaceutical grades. It is subject to standard EU cosmetic ingredient regulations and is typically offered in fibre drums or bags. Buyers should confirm grade specification and purity certificates with the supplier prior to ordering.