Ethyl chlorosulfonate is a reactive organosulfur compound primarily used as a sulfonating agent in organic synthesis for the preparation of sulfonate esters and related derivatives. It serves as a key intermediate in the production of pharmaceuticals, agrochemicals such as pesticides, and dyes. Additionally, it is applied in the chemical industry to modify properties of materials like polymers, coatings, and surfactants. Due to its highly corrosive, toxic, and reactive nature, it must be handled with extreme caution in controlled laboratory or industrial environments under strict safety protocols.