Crystallization and Purification of 4,4′‐Diaminodiphenyl Ether

Abstract The purification of 4,4′‐diaminodiphenyl ether (ODA) was investigated. ODA, which contained impurities, was sublimated and anti‐solvent (ethanol)‐crystallized in N ‐dimethylformamide (DMF). Fourier transform infrared (FTIR) results revealed that the sublimated crystal was basically identical with the pure ODA sample. The influence of different amounts of ethanol on particle size distribution was analyzed during anti‐solvent crystallization. The morphology of the ODA crystal was examined by scanning electron microscopy (SEM). The color of the sample enhanced from a brown powder to a colorless granular crystal. The purity of the sample could be increased from about 30 % to 87 %. With the operations of sublimation and anti‐solvent crystallization, the purity, crystal morphology, and particle size distribution of ODA were significantly improved.