4-Biphenylboronic Acid | CAS 5122-94-1 | ≥98%

4-Biphenylboronic Acid ([1,1′-biphenyl]-4-ylboronic acid) is a π-extended arylboronic acid for installing a rigid 4-biphenyl unit.

May contain small amounts of the cyclic anhydride 4-biphenylboroxine. Under aqueous or basic coupling conditions the two forms re-equilibrate and the impact on yield is minor.

Applications and Reactions

• Suzuki–Miyaura cross-coupling: couples with aryl, heteroaryl, or alkenyl electrophiles to give p-terphenyl, heteroaryl-biphenyl, styrenyl-biphenyl, and higher oligoaryl products.
• Liquid-crystal intermediates: provides a rigid linear biphenyl fragment for terphenyl-type mesogenic cores and rod-shaped aromatic materials.
• Conjugated materials building block: introduces biphenyl segments into π-conjugated oligomers, chromophores, and organic semiconductor intermediates.
• Thiophene–phenylene hybrid scaffolds: with aryl-halide partners gives thienyl-substituted terphenyl and quinquephenyl frameworks for extended heteroaryl–phenylene systems.
• Luminol–peroxidase chemiluminescence enhancement: acts as an enhancer in luminol–hydrogen peroxide–horseradish peroxidase systems, including capillary-electrophoresis chemiluminescence detection.
• Boronate–diol recognition: forms reversible boronate complexes with the diol groups of mono- and disaccharides, used to estimate apparent stability constants in capillary-electrophoresis molecular-recognition studies.

Further Reading

For boronic acids, boronic esters, protodeboronation, boroxine content, and Suzuki–Miyaura reagent selection, see NorrChemica's Lab Journal guide: Choosing Your Boron Source for Suzuki–Miyaura Coupling.