Pyrithione sulphinate

In solution stable between pH 4-5 and 9-5 below pH 4-5 conversion to free Pyrithione which is very unstable in the presence of oxygen or light above pH 9-5 slow conversion to the sodium salt of Pyrithione sulphonic acid. Oxidizing agents such as peroxides and hypohalites will convert Pyrithione first to 2,2 -dithio-bis-pyridine-1,1 -dioxide (Section 11.1.5) and finally to inactive pyrithione sulphinic or sulphonic acid. 

Stable in mineral or acetic acid solutions (formation of soluble acid salts without cleavage of the sulphur-sulphur bond) in alkaline solutions slow cleavage of the disulphide linkage under release of the alkali salts of 2-mercaptopyridine-/V-oxide (see Section 11.1.3) and to a certain extent Pyrithione sulphinate... 

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