4-Iodo-1-butyne is primarily used in organic synthesis as a versatile building block for constructing more complex molecules. Its alkyne functionality allows for various coupling reactions, such as Sonogashira coupling, which is widely employed in the synthesis of pharmaceuticals, agrochemicals, and advanced materials. The iodine atom in the compound serves as a good leaving group, facilitating nucleophilic substitution reactions, making it useful in the preparation of substituted alkynes. Additionally, it is utilized in click chemistry for the formation of triazoles, which are important in drug discovery and material science. The compound’s reactivity also makes it valuable in the development of polymers and dendrimers.