This diboronic ester, also known as 1,4-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzene, presents as a white to very pale yellow crystalline powder. Store in a cool and dark place at ambient temperatures. 1,4-Benzenediboronic Acid Bis(pinacol) Ester is known to be incompatible with oxidizing agents and should not be stored or handled in their vicinity.