Used as an intermediate in the synthesis of azo dyes and pigments, particularly for producing water-soluble dyes with good lightfastness and color brightness. Commonly employed in the textile industry for dyeing wool, silk, and nylon. Also utilized in the preparation of fluorescent whitening agents for paper and detergents. Plays a role in biochemical research as a derivatizing agent for detecting amines and phenols in analytical methods. Its sulfonic acid group enhances solubility, making it suitable for applications requiring polar compounds.