Used primarily as a key intermediate in the synthesis of pharmaceuticals and agrochemicals. Its sulfonyl chloride group readily reacts with nucleophiles like amines and alcohols, making it valuable for constructing sulfonamide and sulfonate ester derivatives. Commonly employed in medicinal chemistry for developing kinase inhibitors and other bioactive molecules. Also utilized in the preparation of fluorescent probes and dyes due to the inherent fluorescence of the quinoline ring. Its reactivity allows for easy functionalization, enabling its use in combinatorial chemistry and high-throughput screening libraries.