Used primarily as a key intermediate in the synthesis of biologically active compounds, especially in pharmaceuticals and agrochemicals. Its sulfonyl chloride group readily reacts with amines and alcohols, making it valuable for constructing sulfonamide and sulfonate ester derivatives. It is particularly useful in medicinal chemistry for developing kinase inhibitors and other targeted therapies due to the quinoline scaffold’s affinity for biological targets. Also employed in the preparation of fluorescent probes and dyes, leveraging the inherent fluorescence of the quinoline ring for sensing applications.