4-Cyclopropylphenylboronic acid is an organoboron compound featuring a boronic acid functional group attached to a benzene ring substituted with a cyclopropyl group. It is a white to off-white crystalline powder commonly used as a key synthetic building block. Its primary application is in Suzuki-Miyaura cross-coupling reactions, a pivotal method for forming carbon-carbon bonds. The boronic acid group readily couples with aryl or vinyl halides in the presence of a palladium catalyst. The cyclopropyl substituent is a valuable structural motif in medicinal chemistry and materials science, often used to modulate the physicochemical properties of target molecules. This compound serves as a crucial intermediate in the synthesis of various pharmaceuticals and, notably, in the development of organic light-emitting diode (OLED) materials and other organic electronic components. As a boronic acid, it requires careful handling under inert atmosphere (e.g., nitrogen or argon) for long-term storage to prevent protodeboronation and maintain reactivity. It is typically stored at low temperatures (2-8°C).