Bis(2-aminophenol) is an aromatic diamine that is a key raw material for the synthesis of polybenzoxazole (PBO) polymers. They react with dicarbonyl compounds to form benzoxazole rings, which are characteristic of PBO polymers. These diamines provide excellent thermal stability and mechanical properties to the resulting polymers. PBO polymers are widely used in aerospace and high-performance textile applications due to their superior properties. Bis(2-aminophenol) is usually prepared by the condensation of phenol with ammonia in the presence of a catalyst.