Diphenylphosphine is widely used as a key reagent in organic synthesis, particularly in the preparation of phosphine ligands for transition metal catalysts. These catalysts are essential in various industrial processes, including hydroformylation, hydrogenation, and cross-coupling reactions, which are critical for producing pharmaceuticals, agrochemicals, and fine chemicals. Additionally, diphenylphosphine serves as a precursor for the synthesis of flame retardants, where it is incorporated into polymers to enhance their fire-resistant properties. It is also employed in the production of photostabilizers and antioxidants, which protect materials from degradation caused by light and oxidation. In coordination chemistry, diphenylphosphine is utilized to create complex structures with metals, enabling the development of advanced materials and catalysts with tailored properties. Its role in these applications underscores its importance in both industrial and academic research.