Used as a flame retardant synergist, particularly in combination with halogenated compounds, to enhance fire resistance in plastics, textiles, rubber, and adhesives. It works by promoting char formation and reducing flammability during combustion. Commonly found in electronic devices, wire and cable coatings, and construction materials where fire safety is critical. Also serves as a catalyst in the production of polyester resins and in the manufacturing of colored glasses and ceramics.