Used as an intermediate in the synthesis of pharmaceutical compounds, particularly in the development of nitrogen-containing heterocyclic drugs. It serves in the preparation of bioactive molecules with potential anticonvulsant, antimicrobial, and anticancer properties. Its reactivity allows for functionalization at the chlorine site, enabling the formation of C–C, C–N, or C–S bonds in medicinal chemistry research. Also employed in the production of agrochemicals and functional materials where phthalazine derivatives are required.