Pyrithionate

Pyrithionate refers to salts and esters derived from pyrithionic acid, the deprotonated form of the pyrithione moiety found in 2-mercaptopyridine N-oxide. The core fragment is a heteroaromatic ring bearing a mercapto group at the 2-position, and the negative charge is typically carried by the sulfur atom after deprotonation. Common examples include sodium pyrithionate, potassium pyrithionate, and zinc pyrithionate.

Pyrithionates are prepared by neutralizing the corresponding pyrithionic acid with a base or by deprotonation of pyrithione-containing salts with alkali metals. The resulting salts can vary in solubility depending on the counterion, with alkali metal salts being generally water-soluble.

In coordination chemistry, pyrithionate ligands can bind to metal centers through the sulfur atom and potentially other donor sites on the pyrithione moiety, enabling formation of various metal–pyrithionate complexes. The properties of these complexes depend on the metal and the counterion.

Applications of pyrithionates arise from the versatility of the pyrithione fragment. Zinc pyrithionate, for instance, is used as an antimicrobial and antifungal agent in consumer products such as shampoos. More broadly, pyrithionate salts serve as reagents and intermediates in organic synthesis and related inorganic applications.

Safety and handling guidelines are similar to those of other sulfur-containing salts: handle with appropriate PPE, avoid inhalation and ingestion, and store away from oxidizers. They can be irritants to skin and eyes under some conditions.