Phenylphosphonous dichloride is primarily used as a key intermediate in the synthesis of various organophosphorus compounds. It is widely employed in the production of flame retardants, where it serves as a building block for creating phosphorus-based additives that enhance the fire resistance of materials such as plastics, textiles, and coatings. Additionally, it plays a significant role in the preparation of ligands for catalysis, particularly in asymmetric synthesis and transition metal-catalyzed reactions. The compound is also utilized in the development of agrochemicals, including pesticides and herbicides, due to its ability to form stable phosphorus-carbon bonds. Furthermore, it finds application in the pharmaceutical industry for the synthesis of biologically active molecules and drug candidates. Its reactivity with alcohols and amines makes it a versatile reagent in organic synthesis, enabling the creation of a wide range of functionalized phosphorus derivatives.