Used primarily in the synthesis of hair dyes and cosmetic colorants due to its ability to form stable, long-lasting pigments when oxidized. It acts as a coupler in oxidative dye formulations, reacting with other dye intermediates to produce a range of shades, especially natural-looking browns and blacks. Also employed in textile dyeing for color fastness on natural fibers. Its sulfate salt form enhances solubility and stability in aqueous formulations. Limited use in pharmaceutical research for heterocyclic compound development.