1-Chloro-4-iodonaphthalene is primarily used in organic synthesis as a versatile intermediate for the preparation of more complex chemical compounds. Its structure, featuring both chlorine and iodine substituents, allows for selective functionalization through cross-coupling reactions, such as Suzuki or Sonogashira couplings, which are essential in the development of pharmaceuticals, agrochemicals, and advanced materials. Additionally, it serves as a building block in the synthesis of organic semiconductors and liquid crystals, which are critical components in electronic devices and display technologies. The compound’s reactivity also makes it valuable in research settings for studying reaction mechanisms and developing new synthetic methodologies.