Dimethyldioctadecylammonium chloride

Dimethyldioctadecylammonium chloride, or distearyldimonium chloride, is a quaternary ammonium salt consisting of a nitrogen atom substituted with two methyl groups and two octadecyl groups. The long-chain hydrocarbon groups combined with the ionic nature of the amine group enables it to act as a surfactant or a detergent.

In household products, it may be found as an ingredient in fabric softeners, cosmetics, and hair conditioners in which it is added primarily for its antistatic effects. It is also used in organic synthesis as a phase transfer catalyst to increase reaction rates in a two-phase organic-water system.