4-Bromo-m-xylene is an organic compound with the molecular formula C8H9Br. It is a colorless to pale yellow liquid at room temperature and is a derivative of m-xylene where one hydrogen atom on the aromatic ring is substituted by a bromine atom. This compound is characterized by its two methyl groups in the meta position relative to each other. The primary application of 4-bromo-m-xylene is as a versatile organic synthesis building block. The bromine atom serves as an excellent leaving group, making it a key intermediate in various cross-coupling reactions, such as Suzuki, Negishi, and Kumada couplings, to construct more complex organic frameworks. Its specific structure makes it a valuable precursor in materials science, particularly for the synthesis of organic semiconductors, liquid crystals, and ligands for metal-organic frameworks (MOFs). It is used in the development of organic light-emitting diodes (OLEDs) and other optoelectronic materials. As a halogenated aromatic compound, it requires careful handling. It is flammable and may cause skin and eye irritation. Proper personal protective equipment and adequate ventilation are recommended during its use in laboratory or industrial settings.