Isostearic acid

Isostearic acid (CAS 2724-58-5) is a branched-chain C18 fatty acid derived from the dimerisation of unsaturated fatty acids, commercially available under trade names including Emersol 873, Prisorine 3505, and Prisorine 3509. Unlike its linear counterpart stearic acid, the branched structure remains liquid at room temperature, giving it distinct handling and formulation advantages.

In personal care formulations, isostearic acid functions as an emulsifier and skin-conditioning agent, where its branched structure reduces crystallisation and improves spreadability in anhydrous systems such as lipsticks and balms. In metalworking lubricants and coatings, it acts as a boundary lubricant and wetting agent, reducing friction at metal surfaces and improving pigment dispersion in alkyd systems.

Isostearic acid is supplied in industrial and cosmetic grades and falls under REACH registration requirements for EU market supply. It carries no E-code designation. Typical packaging includes drums and IBC containers, with kosher and RSPO-certified grades available from select producers.