4-Aminobiphenyl solution is primarily used in research settings as an intermediate in the synthesis of dyes and azo compounds. It serves as a building block in organic chemistry for creating complex aromatic amines and polymers. Due to its reactivity, it is also employed in the development of certain pharmaceuticals and agrochemicals. However, because of its known mutagenic and carcinogenic properties, its use is highly restricted and typically limited to controlled laboratory environments. It is not used in consumer products or industrial applications outside of specialized research.