Picolinic acid is an organic compound with the formula NC5H4CO2H. It is a derivative of pyridine with a carboxylic acid (COOH) substituent at the 2-position. It is an isomer of nicotinic acid and isonicotinic acid, which have the carboxyl side chain at the 3- and 4-positions, respectively. It is a white solid although impure samples can appear tan. The compoundthat is soluble in water.

Production

On a commercial scale, picolinic acid is produced by ammoxidation of 2-picoline followed by hydrolysis of the resulting nitrile: It is also produced by oxidation of picoline with nitric acid. In the laboratory, picolinic acid is formed from 2-methylpyridine by oxidation with potassium permanganate (KMnO4).

Reactions

Hydrogenation of picolinic acid gives piperidine-2-carboxylic acid, a precursor to the drug Mepivacaine. Picolinic acid is a bidentate chelating agent of elements such as chromium, zinc, manganese, copper, iron, and molybdenum in the human body. It is a substrate in the Mitsunobu reaction. In the Hammick reaction, picolinic acid reacts with ketones to give pyridine-2-carbonols:

Biosynthesis

Picolinic acid is a catabolite of the amino acid tryptophan through the kynurenine pathway. Its function is unclear, but it has been implicated in a variety of neuroprotective, immunological, and anti-proliferative effects. In addition, it is suggested to assist in the absorption of zinc(II) ions and other divalent or trivalent ions through the small intestine.

Picolinates

Salts of picolinic acid (picolinates) include: