Phthalanilic acid is primarily used in the synthesis of various organic compounds, particularly in the production of dyes and pigments. Its structure allows it to act as an intermediate in the creation of complex molecules that are essential for coloring agents in textiles, plastics, and inks. Additionally, it finds application in the pharmaceutical industry, where it serves as a building block for the development of certain drugs. Its role in chemical research is also notable, as it is utilized in studies involving organic reactions and the development of new synthetic pathways.