Used as an intermediate in the synthesis of active pharmaceutical ingredients, particularly in the production of non-steroidal anti-inflammatory drugs (NSAIDs). It serves as a key building block in forming ester and amide derivatives due to its carboxylic acid and sulfonic acid functional groups. The sulfonic acid group enhances water solubility, making it valuable in designing compounds with improved bioavailability. Also employed in dye synthesis and as a modifier in polymer chemistry to introduce ionic character and improve thermal stability.