Used as an intermediate in the synthesis of vat dyes, particularly for producing bright and stable blue and green shades. It contributes to the lightfastness and washfastness of dyes applied to cellulosic fibers like cotton. Also employed in the production of fluorescent whitening agents for textiles and paper, enhancing brightness by absorbing ultraviolet light and emitting blue light. Its sulfonate group improves water solubility, facilitating processing in aqueous dye baths.