1-Bromo-4-iodobenzene is a mixed aryl halide (aryl bromide and aryl iodide) with the formula BrC<sub>6</sub>H<sub>4</sub>I.
In 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.
Since 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 (with TMSA being deprotected to acetylene in-situ) to form bis(4-bromophenyl)acetylene.