Chloroiodomethane is primarily used in organic synthesis as a building block for more complex chemical compounds. It serves as a versatile reagent in the introduction of both chlorine and iodine atoms into organic molecules, which is useful in the preparation of pharmaceuticals and agrochemicals. Additionally, it is employed in the synthesis of intermediates for dyes and other industrial chemicals. Its dual halogen functionality allows for selective reactions, making it valuable in research and development for creating specialized organic compounds.