4-Nitroaniline solution is primarily used as an intermediate in the synthesis of dyes and pigments, particularly azo dyes, which are widely employed in the textile, leather, and paper industries. It serves as a key building block in the production of colorants due to its ability to form stable diazonium salts, which react with other compounds to create vibrant colors. Additionally, it is utilized in organic synthesis for the preparation of various pharmaceuticals and agrochemicals, where it acts as a precursor or intermediate in complex chemical reactions. In research and development, it is employed as a reagent in analytical chemistry for the detection and quantification of specific substances. Its application also extends to the production of corrosion inhibitors and antioxidants in industrial processes. Proper handling is essential due to its toxic and potentially hazardous nature.