Isonicotinic acid or pyridine-4-carboxylic acid is an organic compound with the formula C5H4N(CO2H). It is a derivative of pyridine with a carboxylic acid substituent at the 4-position. It is an isomer of picolinic acid and nicotinic acid, which have the carboxyl group at the 2- and 3-position respectively compared to the 4-position for isonicotinic acid.

Production

On a commercial scale, isonicotinic acid, like other pyridine carboxylic acid is produced by ammoxidation of 4-picoline (4-methylpyridine) followed by hydrolysis of the resulting nitrile: It is also produced by oxidation of 4-picoline with nitric acid.

Derivatives

Isonicotinic acids is a term loosely used for derivatives of isonicotinic acid. Hydrazide derivatives include isoniazid, iproniazid, and nialamide. Amide and ester derivatives include ethionamide and dexamethasone isonicotinate. Its conjugate base forms coordination polymers and MOFs by binding metal ions through both the N and carboxylate.