Nitroxyl (HNO/NO−) or hyponitrous acid, in chemistry is the reduced form of nitric oxide (NO). HNO and NO− form an acid/base pair (pKa = 11.4) with NO−isoelectronic with dioxygen. Nitroxyl is very reactive towards nucleophiles (especially thiols) and quickly dimerizes to H2N2O2 which then is dehydrated to nitrous oxide N2O.. Therefore, HNO is generally prepared in situ for example with the compounds such as Angeli’s salt (Na2N2O3) and Piloty’s acid (PhSO2NHOH) when it is needed.
Nitroxyl shows potential in the treatment of heart failure and ongoing research is focused on finding new nitroxyl donors. In one study such donor is prepared by organic oxidation of cyclohexanone oxime with lead tetraacetate to 1-nitrosocyclohexyl acetate:
This compound can be hydrolyzed under basic conditions in a phosphate buffer to nitroxyl HNO, acetic acid and cyclohexanone.
