N,N'-Carbonyldiimidazole (CDI) is widely used as a coupling agent in organic synthesis, particularly for peptide and ester bond formation. It facilitates the activation of carboxylic acids, enabling their reaction with amines or alcohols to produce amides or esters, respectively. CDI is also employed in the synthesis of pharmaceuticals, polymers, and other fine chemicals due to its efficiency and mild reaction conditions. Additionally, it serves as a dehydrating agent in the preparation of anhydrides and carbonates. Its applications extend to the modification of biomolecules, such as proteins and nucleic acids, for research and diagnostic purposes. CDI is valued for its ability to minimize side reactions and produce high yields in various chemical processes.