an organic liquid solvent used in the extraction of uranium and plutonium salts from reactor effluents, as a solvent for nitrocellulose and cellulose acetate, and as a heat-exchange medium. A phosphorus-containing compound with molecular formula (C₄H₉)₃PO₄, it is prepared by reaction of phosphorus oxychloride with butyl alcohol. Tributyl phosphate is corrosive to the skin and irritating to the mucous membranes.