Used primarily as a reagent in organic synthesis, particularly in cyclopropanation reactions via the Simmons-Smith reaction or related transformations. It serves as a source of carbenes when activated by metal catalysts like zinc or copper, enabling the formation of cyclopropane rings from alkenes. This reactivity is valuable in the construction of complex organic molecules, including natural products and pharmaceuticals. Additionally, due to the presence of heavy halogens, it can participate in selective halogenation or act as an intermediate in the preparation of other halogenated compounds. Its use is generally limited to laboratory-scale synthesis because of its instability and sensitivity to light and heat.