Pyrithione, C5H5NOS

• Figure 2. Zinc pyrithione. Public Domain (Chemical Structure)
  
  Pyrithione possesses a six-member ring with nitrogen as the heterocyclic-ring member. On an adjacent carbon atom, a doubly-bonded sulfur is attached. But that is not the complete picture. Pyrithione exists as tautomers. That is, two different structures can be drawn for the same compound, since there is an equilibrium between the structures (Figure 1). Tautomerism frequently involves the transfer of a hydrogen and the conversion of a double bond to a single bond, and vice versa.
  
  

Zinc Pyrithione

• Zinc pyrithione dimer, stick model. Wikimedia Commons
  
  Zinc Pyrithione is an antibacterial, antifungal ingredient used for skin ailments such as dandruff, psoriasis, seborrheic dermatitis, athlete's foot, eczema, and ringworm. Due to its insolubility, pyrithione zinc may be used against mildew and algae in house paints. It may also be added to various polymers and plastics to help preserve finished products made from them.
  
  

Formation of Pyrithione Zinc

• Commercial manufacture is the subject of many patent applications. However, in the laboratory, one way to make zinc pyrithione (Figure 2) is as follows:
  
  Combine pyrithione with concentrated sodium hydroxide solution, heating it with agitation to 90 degrees Celsius for a quarter hour. Then react with concentrated zinc sulfate solution at the same temperature for an hour.
  
  

Chemical Formula for Pyrithione Zinc

• The structure of pyrithione zinc includes a +2 zinc atom chelated with two pyrithione ligands, with the zinc at the center of the specie, bonded by the electron-rich oxygen and sulfur atoms.
  
  

Risks Assessment for Zinc Pyrithione

• Zinc pyrithione may have a generally low-risk profile, yet the Environmental Protection Agency has posted a preliminary risk assessment for it. The chief concerns at this point involve dermal and inhalation exposures. Will boat and house paints possessing the in-can preservative cause problems? And whether that is the case or not, what about those regularly exposed directly to the chemical?
  
  

Material Safety Data Sheet (MSDS)

• Safety is important when using any chemical. MSDS sheets are available on-line for zinc pyrithione. Be sure to consider the MSDS for zinc pyrithione in the specific form you are using, whether in solid or solution form.