Nitric oxide

Not to be confused with nitrous oxide.
This article is about a molecule of one nitrogen atom and one oxygen atom. For other chemical combinations of nitrogen and oxygen, see nitrogen oxide. For the use of nitric oxide as a medication or in biology, see Biological functions of nitric oxide.
Nitric oxide
Skeletal formula of nitric oxide with bond length
Skeletal formula showing two lone pairs and one three-electron bond
Skeletal formula showing two lone pairs and one three-electron bond
Space-filling model of nitric oxide
Space-filling model of nitric oxide
Names
IUPAC name
Nitrogen monoxide[1]
Systematic IUPAC name
Oxidonitrogen(•)[2] (additive)
Other names
Nitrogen oxide
Nitrogen(II) oxide
Oxonitrogen
Nitrogen monoxide
Identifiers
3D model (JSmol)
3DMet
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.030.233 Edit this at Wikidata
EC Number
  • 233-271-0
451
KEGG
RTECS number
  • QX0525000
UNII
UN number 1660
  • InChI=1S/NO/c1-2 checkY
    Key: MWUXSHHQAYIFBG-UHFFFAOYSA-N checkY
  • InChI=1/NO/c1-2
    Key: MWUXSHHQAYIFBG-UHFFFAOYAI
  • [N]=O
Properties
NO
Molar mass 30.006 g·mol−1
Appearance Colourless gas
Density 1.3402 g/L
Melting point −164 °C (−263 °F; 109 K)
Boiling point −152 °C (−242 °F; 121 K)
0.0098 g / 100 ml (0 °C)
0.0056 g / 100 ml (20 °C)
1.0002697
Structure
linear (point group C∞v)
Thermochemistry
210.76 J/(K·mol)
90.29 kJ/mol
Pharmacology
R07AX01 (WHO)
License data
Inhalation
Pharmacokinetics:
good
via pulmonary capillary bed
2–6 seconds
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Very toxic, corrosive, oxidizer[4]
GHS labelling:
GHS03: OxidizingGHS05: CorrosiveGHS06: Toxic[3][4]
Danger
H270, H314, H330[3][4]
P220, P244, P260, P280, P303+P361+P353+P315, P304+P340+P315, P305+P351+P338+P315, P370+P376, P403, P405[3][4]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
3
0
3
OX
Lethal dose or concentration (LD, LC):
315 ppm (rabbit, 15 min)
854 ppm (rat, 4 h)
2500 ppm (mouse, 12 min)[5]
320 ppm (mouse)[5]
Safety data sheet (SDS) External SDS
Related compounds
Related nitrogen oxides
 Dinitrogen pentoxide

Dinitrogen tetroxide
Dinitrogen trioxide
Nitrogen dioxide
Nitrous oxide
Nitroxyl (reduced form)
Hydroxylamine (hydrogenated form)

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Nitric oxide (nitrogen oxide or nitrogen monoxide[1]) is a colorless gas with the formula NO. It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its chemical formula (•N=O or •NO). Nitric oxide is also a heteronuclear diatomic molecule, a class of molecules whose study spawned early modern theories of chemical bonding.[6]

An important intermediate in industrial chemistry, nitric oxide forms in combustion systems and can be generated by lightning in thunderstorms. In mammals, including humans, nitric oxide is a signaling molecule in many physiological and pathological processes.[7] It was proclaimed the "Molecule of the Year" in 1992.[8] The 1998 Nobel Prize in Physiology or Medicine was awarded for discovering nitric oxide's role as a cardiovascular signalling molecule.[9] Its impact extends beyond biology, with applications in medicine, such as the development of sildenafil (Viagra), and in industry, including semiconductor manufacturing.[10][11]

Nitric oxide should not be confused with nitrogen dioxide (NO2), a brown gas and major air pollutant, or with nitrous oxide (N2O), an anesthetic gas.[6]

  1. ^ a b Nomenclature of Inorganic Chemistry, IUPAC Recommendations (PDF). International Union of Pure and Applied Chemistry. 2005. p. 69.
  2. ^ "Nitric Oxide (CHEBI:16480)". Chemical Entities of Biological Interest (ChEBI). UK: European Bioinformatics Institute.
  3. ^ a b c "Nitrogen monoxide - Registration Dossier - ECHA". Retrieved 2020-11-02.
  4. ^ a b c d "Safety Data Sheet - Nitric Oxide, compressed - Registration Dossier" (PDF). Retrieved 2020-11-02.
  5. ^ a b "Nitric oxide". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  6. ^ a b Cite error: The named reference G&E was invoked but never defined (see the help page).
  7. ^ Hou, Y. C.; Janczuk, A.; Wang, P. G. (1999). "Current trends in the development of nitric oxide donors". Current Pharmaceutical Design. 5 (6): 417–441. doi:10.2174/138161280506230110111042. PMID 10390607.
  8. ^ Culotta, Elizabeth; Koshland, Daniel E. Jr. (1992). "NO news is good news". Science. 258 (5090): 1862–1864. Bibcode:1992Sci...258.1862C. doi:10.1126/science.1361684. PMID 1361684.
  9. ^ "The Nobel Prize in Physiology or Medicine 1998". NobelPrize.org. Retrieved 2022-06-17.
  10. ^ Reporter, Kashmira Gander (2020-04-07). "How the Gas That Gave Us Viagra Could Help Treat Coronavirus Patients". Newsweek. Retrieved 2024-08-29.
  11. ^ "Nitric Oxide in Semiconductor Manufacturing: Unveiling the Silent Powerhouse Shaping Our Hi-Tech Future | Plasma Futures". Retrieved 2024-08-29.