Used primarily as a key intermediate in the synthesis of organophosphorus compounds, particularly in the production of flame retardants and plasticizers. It plays an important role in modifying polymer properties by introducing phosphorus-containing groups, enhancing thermal stability and fire resistance in materials such as polyurethanes and engineering plastics. Also utilized in the preparation of ligands for catalysis and in agrochemical synthesis due to its reactivity with nucleophiles. Its high reactivity requires careful handling, but it offers efficient routes to functionalized phosphonate derivatives.