Used primarily in protein sequencing, it reacts with the N-terminal amino acid of a peptide to form a phenylthiocarbamoyl derivative, which can be cleaved and identified. It is also employed in the synthesis of pharmaceuticals and agrochemicals, where it serves as a key intermediate for introducing the phenylthiocarbonyl group. Additionally, it finds application in analytical chemistry as a derivatizing agent for the detection and quantification of amino acids and other compounds. Its role in organic synthesis includes the preparation of heterocycles and other complex molecules.