3-Chloro-2-methylphenylboronic acid is an organoboron compound featuring a boronic acid functional group attached to a 3-chloro-2-methylphenyl aromatic ring. It is a white to off-white crystalline powder with a molecular formula of C7H8BClO2 and a molecular weight of 170.40 g/mol. This compound is a key member of the arylboronic acid family, widely used as a versatile building block in modern synthetic chemistry, particularly in cross-coupling reactions. Its primary application is as a crucial synthetic intermediate in the Suzuki-Miyaura cross-coupling reaction, a powerful method for forming carbon-carbon bonds. This reaction is extensively employed in the pharmaceutical industry for the synthesis of complex molecules, including active pharmaceutical ingredients (APIs) and drug candidates. The presence of both the boronic acid group and the chloro substituent on the aromatic ring makes it a valuable bifunctional reagent, allowing for sequential or selective chemical transformations to construct more elaborate structures. As a research chemical, it is commonly used in the development of new chemical entities and material science. Standard handling precautions for boronic acids should be observed, including storage in a cool, dry place and protection from moisture to prevent deboronation. It is typically used under inert atmosphere conditions in organic synthesis laboratories.