Used primarily as a specialty intermediate in organic synthesis, particularly in the preparation of fluorescent dyes and optical brighteners. Its anhydride group allows for easy attachment to amines or alcohols, making it useful in modifying polymers and resins for enhanced performance in coatings and electronic materials. The propynyl functionality enables click chemistry reactions, especially in bioconjugation and labeling applications where selective coupling under mild conditions is required. Also employed in the development of sensors and functional materials due to its ability to participate in metal-catalyzed coupling reactions.