Understanding the fundamental chemistry of key building blocks is essential for advancing synthetic capabilities. 1-Bromo-4-iodobenzene (CAS 589-87-7) is one such compound, highly valued for its distinct reactivity and ease of synthesis. NINGBO INNO PHARMCHEM CO.,LTD. is dedicated to providing insights into the chemistry behind this versatile molecule.

1-Bromo-4-iodobenzene is a disubstituted aromatic hydrocarbon with the molecular formula C6H4BrI. Its structure features a benzene ring with a bromine atom and an iodine atom positioned at opposite ends (para positions). This arrangement leads to a molecule with a molecular weight of approximately 282.90 g/mol. Physically, it typically presents as a white to brown crystalline powder or crystals, with a melting point typically ranging from 89-91 °C. It exhibits limited solubility in water but readily dissolves in common organic solvents like ethanol, acetone, and chloroform, which is advantageous for its use in various reaction media.

The chemical reactivity of 1-Bromo-4-iodobenzene is largely dictated by the nature of its halogen substituents. The carbon-iodine bond is generally weaker and more polarizable than the carbon-bromine bond. This difference in bond strength and polarity makes the iodine atom more susceptible to certain reactions, such as oxidative addition to transition metal catalysts, and nucleophilic attack. Conversely, the carbon-bromine bond can also be activated, often under different conditions or with different catalysts. This differential reactivity is the cornerstone of its utility in selective synthesis.

The synthesis of 1-Bromo-4-iodobenzene commonly begins with 4-bromoaniline. The process involves a sequence of reactions: first, the diazotization of 4-bromoaniline using sodium nitrite in an acidic medium (e.g., sulfuric acid) to form a diazonium salt. Subsequently, this diazonium salt is treated with a source of iodide, such as potassium iodide, often in the presence of a solvent like chloroform, to achieve iodination. This method is efficient and can yield the desired product in good purity, making it suitable for commercial production. The purity level, often specified as 98% or higher, is critical for its intended applications.

The primary utility of 1-Bromo-4-iodobenzene lies in its role in palladium-catalyzed cross-coupling reactions. As mentioned previously, its dual halogenation enables selective coupling. For example, in a Suzuki-Miyaura coupling, one can first react the aryl iodide with a boronic acid and palladium catalyst. The resulting product, now functionalized at the former iodine position, still retains the bromine atom, which can then be subjected to a second, potentially different, cross-coupling reaction. This stepwise approach allows for the precise construction of complex molecules with multiple aryl or heteroaryl substituents.

Beyond cross-coupling, the halogen atoms can also participate in other reactions, such as halogen-metal exchange. For instance, treatment with organolithium or Grignard reagents can lead to the formation of highly reactive organometallic intermediates, which can then be reacted with a variety of electrophiles. The selective metalation of either the C-I or C-Br bond is a testament to the control afforded by this molecule.

The availability and price of 1-Bromo-4-iodobenzene from reputable suppliers like NINGBO INNO PHARMCHEM CO.,LTD. are crucial for researchers and chemical manufacturers. Understanding its chemical properties and synthetic routes allows for its effective deployment in creating value-added products across diverse industries, from pharmaceuticals to advanced materials.