Zinc Pyrithione (ZPT)

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In the crystalline state, zinc pyrithione (ZPT) exists as a centrosymmetric dime, where each zinc is bonded to two sulfur and three oxygen centers. The pyrithione ligands, which are formally monoanions, are chelated to Zn2+ via oxygen and sulfur centers. In solution, however, the dimers dissociate via scission of one Zn-O bond. Pyrithione is the conjugate base derived from 2-mercaptopyridine-N-oxide, a derivative of pyridine-N-oxide.

CAS No.:


Molecular Formula:


Molecular  Weight:


Structure Formula:

zinc pyrithione structure formula


Item Index
Appearance Off-white Powder
Assay 96 Min.
pH Value (5% solution) 6.5-8.5
Drying Loss 0.5% Max.
Melting Point 240 deg. C Min.


Due to its low solubility in water (8ppm at pH 7), zinc pyrithione (ZPT) is suitable for use in outdoor paints and other products that provide protection against mildew and algae. It is an effective algaecide.

Zinc pyrithione is chemically incompatible with paints relying on metal carboxylate curing agents. When used in latex paints with water containing a high amount of iron, a sequestering agent that will preferentially bind the iron ions is needed. Zinc pyrithione decomposition by ultraviolet light is slow, providing years of protection even against direct sunlight.

Packing and Storage:

Stored in tightly closed containers in a cool, dry area. Avoid light. Content is unchanged in two years.

Safety Protection:

Zinc pyrithione is safe when used as an anti-dandruff agent in rinse-off hair care products and the concentration does not exceed 2%. Avoid contact with eyes and skin, and avoid inhalation of steam. Wash hands after use and prohibit eating or drinking in the workplace.


OM-1563, Zinc pyridine thioneone, de-squaman, N-HYDROXYPYRIDINETHIONE ZINC SALT, zincpolyanemine, bis(1-hydroxy-2-(1h)-pyridinethionato) zinc


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