4-Methoxyphenylboronic acid is an aromatic boronic acid derivative characterized by a boronic acid group (-B(OH)₂) attached to a para-methoxyphenyl ring. It is a white to off-white crystalline powder with a molecular formula of C₇H₉BO₃ and a molecular weight of 151.96 g/mol. This compound is a versatile and widely used building block in organic synthesis, particularly in Suzuki-Miyaura cross-coupling reactions. The boronic acid group enables efficient palladium-catalyzed coupling with aryl or vinyl halides to form biaryl or styrene derivatives, which are core structures in many advanced materials and pharmaceuticals. Its primary application is as a key synthetic intermediate in the preparation of various organic compounds. Beyond its role as a general synthetic reagent, 4-methoxyphenylboronic acid serves as a crucial precursor in materials science. It is employed in the synthesis of organic light-emitting diode (OLED) materials, liquid crystals, and other organic electronic components where the introduction of a methoxyphenyl moiety is required to tune electronic properties, solubility, or molecular packing.