1-Bromo-4-iodobenzene1-Bromo-4-iodobenzene is a mixed aryl halide with the formula BrC6H4I.PreparationIn one laboratory route to 1-bromo-4-iodobenzene, 4-bromoaniline is treated with concentrated sulfuric acid and sodium nitrite to form the diazonium salt, which is then treated with potassium iodide to form 1-bromo-4-iodobenzene.ReactionsSince aryl iodides are more reactive than aryl bromides in the Sonogashira coupling, the iodine end of 1-bromo-4-iodobenzene can be selectively coupled to a terminal acetylene while leaving the bromine end unreacted, by running the reaction at room temperature. For example, two equivalents of 1-bromo-4-iodobenzene can couple to trimethylsilylacetylene in a room temperature symmetrical Sonogashira coupling to form bisacetylene.