The change of an arj lboronic acid to its anhydride, which sometimes occurs when the acid is simply warmed in an anhydrous solvent, can be detected by examination of the infrared absorption spectrum of the sample. As a result of the change, the hydroxyl absorption band of the acid disappears and a new absorption near 700 cm.-', characteristic of the anhydride, appears. The bromination of p-tolueneboronic acid in carbon tetrachloride is found to ...
