Iodoacetic anhydride is primarily used in organic synthesis as a versatile reagent for introducing the iodoacetyl group into various molecules. It is particularly valuable in the modification of proteins, peptides, and other biomolecules, where it facilitates the creation of covalent bonds with thiol groups, enabling the study of protein structure and function. Additionally, it is employed in the preparation of iodoacetamide derivatives, which are useful in biochemical research for labeling and crosslinking applications. Its reactivity with nucleophiles also makes it a key component in the synthesis of complex organic compounds, including pharmaceuticals and agrochemicals.