2-Bromo-3-thiophenecarboxylic acid is an organic compound featuring a thiophene ring substituted with a bromine atom at the 2-position and a carboxylic acid group at the 3-position. It is a white to off-white crystalline powder with a molecular formula of C5H3BrO2S and a molecular weight of 206.99 g/mol. This compound serves as a versatile and important heterocyclic building block in pharmaceutical and agrochemical research. The bromine atom is a reactive site amenable to various cross-coupling reactions (e.g., Suzuki, Stille), while the carboxylic acid group allows for further derivatization into amides, esters, or other functional groups. Its primary application is as a key intermediate in the synthesis of active pharmaceutical ingredients (APIs) and drug candidates, particularly those containing functionalized thiophene cores. As a bifunctional synthon, it is also utilized in materials science for constructing conjugated systems and in the development of organic semiconductors. It should be handled with care, using appropriate personal protective equipment, as it may cause skin and eye irritation.