Nitroxyl
Names | |
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IUPAC name
Azanone
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Systematic IUPAC name
Oxidanimine[1] | |
Other names
Hydrogen nitroxide
Hydrogen oxonitrate(I) | |
Identifiers | |
3D model (
JSmol ) |
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ChEMBL | |
ChemSpider | |
MeSH | Nitroxyl |
PubChem CID
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UNII | |
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Properties | |
HNO | |
Molar mass | 31.014 g·mol−1 |
log P | 0.74 |
Structure | |
Digonal | |
Bent | |
Thermochemistry | |
Heat capacity (C)
|
33.88 J K−1 mol−1 |
Std molar
entropy (S⦵298) |
220.91 J K−1 mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
Nitroxyl (common name) or azanone (IUPAC name)
Generation
Nitroxyl is produced from the reagents Angeli's salt (Na2N2O3) and Piloty's acid (PhSO2NHOH).[5] Other notable studies on the production of HNO exploit cycloadducts of acyl nitroso species, which are known to decompose via hydrolysis to HNO and acyl acid. Upon photolysis these compounds release the acyl nitroso species which then further decompose.[6] HNO is generated via
This compound can be
.Alkali metals react with nitric oxide to give salts of the form MNO (M = metal).[9] However, generation of the (unstable) free acid from these salts is not entirely straightforward (see below).
Reactions
Nitroxyl is a
- 1HNO + B− → 3NO− + BH
Due to the spin-forbidden nature of deprotonation, proton abstraction is many orders of magnitude slower (k = 4.9×104 M−1 s−1 for deprotonation by OH−) than what one would expect for a heteroatom proton-transfer process (processes that are so fast that they are sometimes diffusion-controlled).
The Ka of starting from or ending with the electronic excited states has also been determined. When process of deprotonating singlet state HNO to obtain singlet state NO− has a pKa is about 23. On the other hand, when deprotonating triplet HNO to obtain triplet NO−, the pKa is about −1.8.[10][11]
Nitroxyl rapidly decomposes by a bimolecular pathway to nitrous oxide (k at 298 K = 8×106 M s):[10]
- 2 HNO → N2O + H2O
The reaction proceeds via dimerization to hyponitrous acid, H2N2O2, which subsequently undergoes dehydration. Therefore, HNO is generally prepared in situ as described above.
Nitroxyl is very reactive towards nucleophiles, including thiols. The initial adduct rearranges to a sulfinamide:[11]
- HNO + RSH → RS(O)NH2
Detection
In biological samples, nitroxyl can be detected using
Medicinal chemistry
Nitroxyl donors, known as nitroso compounds, show potential in the treatment of heart failure and ongoing research is focused on finding new molecules for this task. [citation needed]
See also
- Nitroxyl radicals(also called aminoxyl radicals) — chemical species containing the R2N−O• functional group
References
- ^ "Nitroxyl". PubChem. Retrieved August 24, 2022.
- hdl:11336/68714.
- ISBN 978-0-08-037941-8.
- ISBN 978-0-12-352651-9.
- PMID 7783118.
- PMID 12568581.
- PMID 16866522.
- ISBN 978-0-442-29285-0.
- LCCN 63-14307– via the Internet Archive.
- ^ PMID 12032284.
- ^ PMID 27555493.
- PMID 26550842.