Isostearic acid

Isostearic acid (CAS 30399-84-9, EC 250-178-0) is a branched-chain C18 fatty acid derived from the dimerisation of oleic acid, with the monomer fraction isolated as a co-product. It carries no E-code designation. It is commercially available under trade names including Emery 875D and the shorthand designations 875D and 875d.

In personal care formulations, isostearic acid functions as an emulsifier and co-emulsifier, improving the stability of water-in-oil systems through its branched structure, which reduces crystallisation and maintains fluidity at low temperatures. In lubricant and metalworking applications, it serves as a base for metallic soap formation, providing film-forming lubrication and corrosion inhibition on metal surfaces.

Isostearic acid is subject to REACH registration requirements for EU supply and is handled as an industrial-grade oleochemical. It is typically supplied in liquid form in drums or intermediate bulk containers. Suppliers should be consulted directly for specific grade specifications and available pack sizes.