4,4'-Dihydroxydiphenyl (DOD) is widely used as a key intermediate in the synthesis of high-performance polymers, particularly polycarbonates and epoxy resins. Its application in these materials enhances thermal stability, mechanical strength, and chemical resistance, making it suitable for use in automotive, electronics, and construction industries. Additionally, DOD serves as a precursor in the production of flame retardants, contributing to improved safety in textiles and plastics. It is also utilized in the development of specialty coatings and adhesives, where its properties help achieve durability and performance in demanding environments. In the pharmaceutical sector, DOD is employed in the synthesis of certain active pharmaceutical ingredients (APIs) due to its structural versatility.