2-Phenylmaleic acid is primarily used in organic synthesis as a building block for creating more complex chemical structures. It serves as a key intermediate in the production of pharmaceuticals, particularly in the development of compounds with potential therapeutic properties. Its reactive double bond and carboxylic acid groups make it useful in Diels-Alder reactions, where it acts as a dienophile to form cyclic compounds. Additionally, it is employed in the synthesis of polymers and resins, contributing to materials with specific mechanical and thermal properties. In research, it is also utilized to study reaction mechanisms and to develop novel organic molecules with applications in various industries.