Used primarily as an intermediate in the synthesis of reactive dyes, especially for cotton and other cellulosic fibers. It enables the formation of stable covalent bonds between the dye molecule and the fiber, enhancing color fastness to washing and light exposure. Also employed in the production of agrochemicals and pharmaceuticals due to its ability to selectively transfer chloro and amino groups in organic transformations. Its reactivity allows for stepwise substitution, making it valuable in fine chemical synthesis where controlled functionalization is required.