Nitric acid concentrated acid and nitric oxide for dilute acid. or Concentrated nitric acid oxidizes I, P, and S into HIO, HPO, and HSO, respectively. Nitric acid reacts with proteins to form yellow nitrated products. This reaction is known as the xanthoproteic reaction. This test is carried out by adding concentrated nitric acid to the substance being tested, and then heating the mixture. If proteins that contain amino acids with aromatic rings are present, the mixture turns yellow. Upon adding a base such as ammonia, the color turns orange. These color changes are caused by nitrated aromatic rings in the protein. Xanthoproteic
Phenylboronic acid with BBr, followed by hydrolysis form phenylboronic acid. Aryl halides or triflates can be coupled with diboronyl reagents using transition metal catalysts. Aromatic C-H functionalization can also be done using transition metal catalysts. The dehydration of boronic acids gives boroxines, the trimeric anhydrides of phenylboronic acid. The dehydration reaction is driven thermally, sometimes with a dehydration agent. Phenylboronic acid participates in numerous cross coupling reactions where is serves as a source of a phenyl group. One example is the Suzuki reaction where, in the presence of a Pd(0) catalyst and base, phenylboronic acid and vinyl halides are coupled to produce