Used as an intermediate in the synthesis of sulfur-containing dyes and pigments, particularly in the production of vat dyes and reactive dyes for textile coloring. Its aldehyde and sulfonate groups allow for easy functionalization, making it valuable in building complex dye molecules with good water solubility and fiber affinity. Also employed in the preparation of photochromic compounds and organic semiconductors due to its conjugated structure and stability. Additionally, it serves as a building block in some pharmaceutical syntheses where sulfonated aromatics are required for enhancing solubility or biological activity.