Chapter 8 – Hypothiocyanite

Thiocyanate (SCN−) is the usual substrate for the human defensive peroxidases (components of human innate defense that include lactoperoxidase, salivary peroxidase, myeloperoxidase, and eosinophil peroxidase). The initial product of the peroxidase-catalyzed oxidation of SCN− by hydrogen peroxide is the antimicrobial agent hypothiocyanite (OSCN−). Stoichiometric methods of preparing OSCN− are also known. This review addresses the synthesis and chemistry of OSCN− and its derivatives in general, with particular attention paid to reactions that may be biologically relevant and to the evidence for putative biological intermediates. As SCN− is considered to be a pseudohalide in several aspects of reactivity, the inorganic chemistry of OSCN− is, not surprisingly, related to the corresponding hypohalites, albeit complicated by reactions of the cyano moiety of OSCN−.