Diphenylphosphine oxide is widely used as a key intermediate in organic synthesis, particularly in the production of pharmaceuticals and agrochemicals. It serves as a precursor for the synthesis of various phosphine ligands, which are essential in catalysis, especially in transition metal-catalyzed reactions. The compound is also employed in the development of flame retardants due to its ability to enhance the thermal stability of materials. Additionally, it finds application in the preparation of organophosphorus compounds, which are utilized in the manufacture of specialty chemicals and polymers. Its role in the synthesis of optically active compounds makes it valuable in the field of asymmetric synthesis, contributing to the production of chiral drugs and fine chemicals.