Interactions between Isoniazid and α-Hydroxycarboxylic Acids

Abstract

The present study refers to the preparation of isonicotinic acid hydrazide (isoniazid, inh) co-crystals with two α-hydroxycarboxylic acids. The interaction of glycolic acid (H2ga) or DLmandelic acid (H2ma) resulted in the formation of co-crystals or salts of composition (inh)•(H2ga) (1) and [Hinh] + [Hma] − •(H2ma) (2) when reacted with isoniazid. An N'-(propan-2-ylidene)isonicotinic hydrazide hemihydrate, (pinh)•1/2(H2O) (3), was also prepared by condensation of isoniazid with acetone in the presence of glycolic acid. The prepared compounds were well characterized by elemental analysis, and spectroscopic methods, and their three-dimensional molecular structure was determined by single crystal X-ray crystallography. Hydrogen bonds involving the carboxylic acid occur consistently with the pyridine ring N atom of the isoniazid and its derivatives. The remaining hydrogen-bonding sites on the isoniazid backbone vary based on the steric influences of the derivative group. These are contrasted in each of the molecular systems.